Genetic Resources for Tropical Agriculture by International Institute of Tropical Agriculture

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ABOUT IITA The International Institute of Tropical Agr iculture (IITA) was established in 1967 to increase the productivity of key food crops and to deve lop sustainable agricultural systems that can replace bush fallow, or slash-and-burn. cultivation in the humid and subhum id trop ics . It was the first major African link in an integrated network of international agricu ltural research and training centers located in all the major developing regions of the world . The Federal Republic o f Nigeria provided 1,000 hectares 01 land tor the Institute 's headquarters , an e)(perimental farm at Ibadsn. The Ford and Rockefeller foundations provided the initial financial support. Research and tra ining are conducted at the headquarters farm and in other areas of Africa in cooperation with regional and national programs. Although the "geographic mandate" of IITA includes the humId and subhum id tropical regions of the world , IITA is primarily dedicated to improving the farm ing systems in the major agroecological zones of West and Central Africa . Four out of five of the principal research programs of IITA are cropcentered : Grain Legume Improvement, Maize Research , Aice Research , and Root, Tuber. and Plaintain Improvement. The fifth is the Resource and Crop Management Program . Research findings at UTA's headquarters and substations and in the se lected zones have relevance for tropical zones elsewhere in Africa and on other continents. IITA shares these findings with others through germplasm exchange, pub lications, and training . Financ ial support for the core program in recent years has been provided by: Australia , Austria , Belgium, Canada, China, Denmark, Federal Republic of Germany. Ford Foundation, France. India, Italy, Japan , Netherlands , Nigeria , Norway, Private Ass istance in International Development, Sweden , Rockefeller Foundation . United Kingdom , United Nations Development Program, United States, and World Bank. In addition, the following organizations and governments have prov ided funds for special projects and specific training activities; African Deve lopment Bank, Belgium, Canada, Comm iss ion of the European Commu nities in Nigeria, Gatsby Charitable Foundation , Federal Republic of Germany, Ford Foundation , International Development Research Centre, International Fund for Agricultural Developmenl,lta ly, Nigeria, United Nations University, United States, Union Carbide Corporation, University of Hohenheim , and the World Bank. Th is booklet describes some of the recent achievements and activities of the Genetic Resources Unit of IITA in germplasm collection , conservation, evaluation, documentation, and distribution.

More detailed information on Ihese subjects and the other research activities of liT A are contained in the UTA annual report and research highlights volume, which can be obta ined by writing to ; Director-General, lnternationallnstitute of Trop ical Agriculture , PMB 5320 , Oyo Road, lbadan, Nigeria.

Genetic resources for tropical agriculture An introduction to the Genetic Resources Unit of IITA

SECTION 1

The importance of diversity

IITA's Genetic Resources Unit

SECTION 2

From the depths of a continental gene pool Plants on file How to keep seeds for posterity Life history of a germplasm accession at /ITA Yours for the asking Resources for all to use

11 14 15 16 21 22

SECTION 3

Yams

25 28 29

Rice

Bambara ground nut

31 33

Practical applications Cowpeas

Request form for obtaining germplasm from /ITA

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SECTION 1

THE IMPORTANCE OF DIVERSITY T

he world's crops are increasing their yields. but from ever fewer crop varieties. The genetic base of the world 's food is shrinking, at an ever faster rate . Genetic resources are being lost to changing tastes , industry. urbanization, mechanization of farming, and commercialization of agriculture, and to the push for high yields, the preference for improved varieties and the consequent disuse of traditional varieties. Poor countries , understandably. tend to allocate their limited resources and specialists to short-term food production programs, but the danger is that varieties without immediately apparent economic value are ignored. And yet these may be the varieties that contain the solution to problems that might not yet have surfaced - a new disease or a newly imported insect pest, for example. Africa, which is the center of origin of such important crops as African rice , sorghum , pearl millet, two kinds of yam, watermelon, cow peas, coffee, grasses, wheat, barley, oil palm , and castor seed, depends not only on imported food but, increasingly, on imported crop varieties. Eighty-seven percent of the food that Africa grows itself derives from non indigenous varieties. But indigenous

varieties are fast disappearing - both wild species and the so-called land races , or the traditional cultivars used in geographically restr icted areas by local farmers as the result of generations of selection.

In 1848, the lamlne resulting Irom near totallailure 01 the Irish potato crop was the Indirect consequence 01 the lact that the entire crop was based on only a lew varieties 01 potato, which were no! resistant to the fungus Phytophlhora Infeslans. That tragedy, which directly killed over 2 million people and changed the course 01 history lor an entire European country, could have been prevented by genetic diversification 01 the potato crop. In 1970, 15 percent 01 the US maize production and hundreds of millions 01 dollars were lost to a previously minor fungus, HBlmin/hosporium maydis. The Bezostaja variety of wheat spread over 15 million hectares during a series of unusually warm Soviet winters; but In 1972. when temperatures returned to a normal level 01 cold, the result was the loss of millions 01 tons of wheat

...

lant geneticists cannot make growers vary their crops, but they can ensure that the basic genetiC material, or germplasm, from which the varieties are derived will not become extinct - that is, those varieties thai can still be saved. One out of ten recorded wild species is in danger of extinction or is extinct already. And a lost gene can

fllTIE NIUIE

never be recovered . Future diseases and insect pests may well be immune to today's chemical control , and one way to develop new resistant varieties is to seek resistant genes in preserved germplasm . Spontaneous changes, or mutations, which occur at different rates in different traits of plants, accumulate over millions of years of the evolution of the organism. Diversity among domesticated plants is created through natural selection and isolation of varieties either by trial and error or, now, by the application of scientific principles and methods. Plantbreeding methods permit these differences to be manipulated and combined or certain features to be isolated in certain crops. More than 99 percent of the variability in cultivated crops and their wild relatives used by breeders has arisen naturally and spontaneously, even though the mean s to induce mutations in plant breeding have been known for about 60 years .

The terms "germplasm " and "genetic resources" are used interchangeably to denote the hereditary materials In plants and animals that carry the genetic Information by which characterisIIcs or traits are transmitted from parents to their offspring, and from one generation to another. This genetic informalion also contains the variety's resistance to diseases and pests and other traits which may not be needed today but which may well be useful to future generations. In concrete terms, germplasm is seeds, bulbs, roots and tubers, and cuttings, all 01 which can be stored lor long periods and regenerated when plant breeders need to look for speclflc characteristics.

hat does conservation of genetic resources , or germplasm , entail? First of all , the material must be collected , either by explorers (especially in the case 01 wild species) or from farmers or other breeders. Then it must be stored. There are three basic kinds of germ plasm storage: in situ, ex situ, and in vitro, In situ, or "i n place. " conservation entails growing the plants in their natural habitats. usually in protected areas. Although many scientists consider in situ conservation of genetic resources within trad itional agroecosystems to be the ideal strategy, it presents a great many practical difficulties and risks to the germplasm it is intended to protect. In ex situ, or "off-site," conservation , carefully dried and prepared seeds are stored under optimum conditions and regenerated as needed . Th is method keeps germplasm, in the form of seeds, safe from disease, pests, and human error which could put at risk plants that are preserved in fields. Ex situ seed storage units are commonly known as gene banks. Another ex situ conservation method consists in keeping live plants in nurseries or orchards called "field gene banks." These are, however, costly to

n.u. cultu",

maintain properly, take up a great deal of space, and cannot contain a really large proportion of the genetic materials from which they were collected . A third method of genetic resources conservation involves keeping live plant tissue from which new plants can be cloned. This method, which is called ;n vitro because the samples are kept in glass test tubes , is best suited to plants, such as roots and tubers , that either do not produce seeds at all or produce seeds that may not resemble the mother plants. It is also extremely useful and important as a clean way of transporting diseasefree plant material , since full-grown plants may harbor diseases and tenacious insect pests. Genetic resources conservation does not end with collecting and storing. As much emphasis - and commensurate aid - should be given to maintaining and evaluating materials, and to making the germplasm material and information accessible to scientists. These activities are as essential to the conservation effort as collecting and storing. Together they form an integrated system that provides an information base on which investigators can draw in choosing plant varieties for research .

6pftChJIIBI S. Y. NrI 6110... In vitro .."""..

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GENETIC RESOURCES CONSERVATION

Technician M. OIayoM sterlllzee plant_ lor an in vitro cultu",.

IITA'S GENETIC RESOURCES UNIT

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s early as 1970 scientists from the International Institute of Tropical Agriculture (UTA). in Ibadan, Nigeria, began to collect germplasm samples for their work in the Institute's three crop improvement programs on roots and tubers, grain legumes, and cereals . By the mid-1970s, they had assembledfrom existing national , regional , and international collections. and from the fields of West African farmers thousands of samples of liTA mandated crops. Those crops were legumes (cowpeas, lima beans. and soybeans), cereals (rice and maize), and roots and tubers (cassava, sweet potato, yam , and cocoyam) . The collection was used mainly for adaptive selection and plant breeding, but the Institute early on recognized the need for a program of genetic resources conservation . In 1971 the Consultative Group on International Agricultural Research (CGIAR) was founded as a source of support to the system of agricultural research centers around the world . One year later a CGIAR working group called for creation of a network of nine regional genetic resources centers and a series of institutions for collection of genetic material of certain genetically

endangered food crops. As a result, in 1974 the International Board for Plant Genetic Resources (IBPGR) was founded in Rome and, like IITA, is a member of CGIAR. IITA's Genetic Resources Unit was officially established in October 1975 to collect and conserve germplasm. The several thousand samples from the existing collections were transferred to the new Unit from the crop improvement programs. The Unit's original purpose was the collection, conservation, and study of food legumes, roots and tubers , rice , and their wild relatives in subSaharan Africa . In the course of its activities, its objectives have evolved. When , in 1979, the IITA Root and Tuber Improvement Program established a tissue culture laboratory, the Genetic Resources Unit transferred its cassava and yam clones there , because the new

IlTA'S CROP MANDATE cassava

Man/hot esculenta

cowpea

Vigna unguiculata

maize

Zea mays

plantain

MuSB sp.

rice

Oryza sativa and O. glabBrrima

soybean

Glycine max

sweet potato

Ipomoea batatas (mandate to be transferred to the International Potato Center in 1989)

yam

Dioscores sp.

. .UPUI OFIEIETIC IEllIIICEJ LAIlllATDIY

1 Tempor.ry Mted slore, 15-17-<:, 15-2OY. RH 2 Active collection Hftd store II, S-C, 3O-35Y. RH,11O m J 3 Active collection _ed store I, S-C, 30-3SY. RH, 211.6 m J 4 Flnt stage drying, threshing, cl . .nlng, .net sorting .re done in ttt. threshing bulkUng, adlecent to the genetic resources lebor.lorJ. S B... collection aeed stewe, -20-C, II m J ,

6 7 a 9

10 11 12 13

houMCI In . . . per." building, Installed In 1112. It... collection aeed store, -20-C, 132.3 m J Germln.tton I.bor.tory Drylng.net canning room omc..nd mlcroecope room Conference.net computer room 0fIIce s.cNlllry 0fIIce

IlTA AND IIE.MPLASM CONSERVATION

1970

IITA begins collec1lng germplasm lor I1s crop Improvement program

1972

Consultative Group on Intarnallonal Agricultural Research working group calls lor craallon of a network of nine reglonel genetiC resources centers and a series of Institutions for collectlon of genetiC material of specific crops

1974

International Board for Plant Genetic Resources is founded in Rome

1975

Genetic Resources Unit Is founded atliTA. lbadan

1976 onward

52 plant collecting missions In 28 African countries

1978-87

Genetic Resources Unit distributes 33.888 samples of crop germplasm to researchers in more than 80 countries

1987

New facililles are dedlcatad. 10 March. with equipment donated by the italian Government

laboratory was better equipped for in vitro conservation. Lima beans, of wh ich there were about 1,000 accessions, were transferred to Centro Internacional de

Agricultura Tropical (CIAT) . in Colombia, when IITA stopped work on the crop . In 1982 accessions of 1,300 soybean varieties were transferred from the liTA Grain Legume Improvement Program. which had been keeping them , to the Genetic Resources Unit. Today the Genetic Resources Unit of liTA is storing more than 40,000 accessions of germplasm of various crops. of which 36,062 are grain crops, including 15,100 accessions of cowpeas ,

11 ,458 of rice , 1,400 of soybeans, 5,000 of maize. about 2,000 of Sambara groundnut, and a few hundred winged bean. African yam beans, and other miscellaneous species. All grain crop germplasm is

preserved by the Unit. Cow peas and rice , the largest collections , have always received highest priority in the Unit. The cowpea collection from over 100 countries is the largest in the world . The rice collection provides a crucial supplement to the germpl,asm held by the International Rice Research Institute

(IRRI), in Los Banos, Philippines, by covering the African domesticated and wild rice species and the land races of Asian rice which have evolved in Africa. Although Sambara groundnut does not fall within IITA's mandate, the Unit is taking responsibility for collecting and storing this crop so that an important genetiC resource will not be lost. As always, the Unit collects germplasm of all of liTA 's mandated crops. Recently it has been placing great emphasis on yam col lection, evaluation , and documentation ,

he Genetic Resources Unit is supported mainly with " core " funds which are provided by IITA's donors and receives direct grants for special projects. For example, IBPGR provided a grant for a Survey of African Plant Genetic Resources begun in 1982, and a grant from the German Agency for

facility. The Italian Government has also supported research on cowpeas at the Unit and collaborative research with Italian institutions.

FUNDINS

ITA's Genetic Resources Unit is involved in four basic activities (a) acquisition, or collection , of the germplasm , (b) characterization , evaluation, and documentation of the germ plasm, (c) storage, and (d) distribution. In addition, the Unit engages in research and tra ining.

ACTlImES

Technical Cooperalion (GTZ) allowed about 2.000 accessions of Sambara groundnul to be rejuvenated , multiplied, evaluated, and documented. A special donation from the Italian Government provided funds for the reconstruction , extension , and modernization of the

NETWDIK OF FUNDINS AIID COWIDUlIIE ACTIVITIES IN SEIMPLASM CDNSEIIATIDN BETWEEN IITA AND DTHEI INSTITUTIONS

donors

CGIAR

/ l.oI I'

IBPGR

IITA

other CGIAR-alliliated centers

national agricultural research systems

other gene banks

other international agricultural research institutes /

SECTION 2

FROM THE DEPTHS OF ACONTINENTAL GENE POOL EXPLORATION AND COLLECTION

he Genetic Resources Unit has located and acquired germplasm of both wild and domesticated crop species for the Institute and for other centers. So far the Unit has organized some 52 collecting expeditions to 28 African countries , always in collaboration with African scientists and agricultural authorities and also with ISPGR. In recent years, in order to increase genetic diversity for plant breeding, the Unit has emphasized the collection of wild species. especially of Vigna (cowpea) and Oryza (rice) as well as cu ltivars of crops within the liTA mandate that were not adequately collected on earlier expeditions. Between 1985 and 1987, five missions collected Vigna species in south and southeastern Africa, their center of diversity. In 1987 alone, plant exploration missions went to eight African countries and collected a total of 2.783 samples of many different crop species. IITA plant explorers are highly trained plant scientists with a taste for adventure. In their search for unknown or endangered varieties of cow peas, African rice, Bambara groundnuts, maize, yam , cassava, and other species, they have

Plant scientist A.E. GoJi collects wild cowpea specimens in Zambia.

Countries explored since 1976

GAMBIA

MADAGASCAR

Over 50 plant exploration minions In 28 African countrle. have been

carried out by IITA since 1976.

AE. Goll uses a dugout canoe in his search for wild rice in Zambia. ventured into the remotest corners of Africa , risking life and limb, contracting tropical diseases far from anything resembling medical care, and, at least once, being sent packing by a hungry pride of lions. But collecting also means interviewing farmers about the existence of highly localized land races and visiting local markets in the hope of finding a new kind of seed that exists only in an extremely limited geographical area. Every expedition Is preceded by a systematic and thorough review of the literature and other material on the target area. liT A plant explorers always leave a duplicate set of samples in the country of origin . Another source of germplasm is other collectors , either scientists who have acquired a particular variety but who lack storage facilities , or other gene banks which place duplicates of their holdings with the Genetic Resources Unit for safekeeping . Sometimes explorers from other institutions provide the Unit with seed from places its own explorers cannot go.

s. Padulosi, IITA plant explorer, selects new germplasm samples from a farmer 's granary in Chad.

PLANTS ON FilE CHARACTERIZATION AND EVALUATION

Germplasm is Hgrown out " in the field (or characterization and evaluation.

ermplasm is usefu l to scientists and plant breeders only when the material has been properly characterized and evaluated . In this way scientists are able to study the diversity of a species, to search for material for direct introduction as cultivars , or to provide genetic variability in breeding programs. At IITA, many of the accessions, especially of cowpea and rice , are "grown out" every year for characterization and evaluation in IITA's laboratories and experimental fields. For instance, in 1987, 699 accessions of cowpeas , 1,080 of rice , and 1,350 of soybeans were characterized for up to 31 , 41, and 4 cha racters respectively by staN members in the Genetic Resources Unit. In addition , 5,000 cowpea accessions were evaluated for resistance against pod borers, and 1,000 rice accessions were evaluated for blast resistance screening. A computer file is kept for each accession with four categories of information:

• Descriptive data recorded at the time of collection during exploration (passport data): • Data on agrobotanical characters taken at the time of field and laboratory evaluation, with 44

jl99 NEW CIlW!1EJ\ I:OllHTIIlNS SOW~ 12. .S.86

characters for rice , 29 characters for cowpeas , 38 characters for Bambara groundnut, and 40 characters for yam ; • Data on disease, insect, and pest resistances or on resistance to phys iological stresses; • Information on seed store management, including the records of seed quantities, location of the sample in the store, date the sample entered the store, and the percentage of seed viability. In addition, as new information emerges, in the form of either published research or feedback from breeders, it is recorded in the appropriate file . The computerized retrieval system will iden tify accessions that possess specified characteristics. The genetiC resources information stored in the computer file can be analyzed so that the variation of a character can be studied or so that pairs of characters can be correlated.

Field evaluation of cowpeas growing at IITA

HOW TO KEEP SEEDS FOR POSTERITY he heart of a gene bank is, of course, its processing and storage facilities . IITA is fortunate in having modern new facilities and storage rooms , completely reconstructed during 1986-1987 with the help of a grant from the Italian Government. The new facilities are sufficient to contain more than 60,000

accessions of plant germ plasm. A plant specimen that has been collected outside Nigeria must pass postentry observation by the Nigeria Federal Department of Agriculture , Plant Quarantine Service, at Ibadan. It then comes to the Genetic Resources Unit at IITA, where it is registered and placed in

SEED-STORAGE LINKAGES wild Vigna Belgium

cowpea (all)

USA

rice Japan'

. -r::..,:.:. __ .

Bambara groundnut Federal Republic of Germany'

cowpea (part)

Italy •

1 Faculte de. Kiene •• egronomlques de ,'Et... Oembloua:, Belgium 2 N.tlOMI s..d Stor.... L..bontory, Fort Collins, Coforedo, USA 3 N.Uon.sllnettlute of AvrobIoIoglc.sl "esources, Tsutub8, J.~n 4 Irmltut Klr Ptl.nzenb.u und PflenzenzOc:hlUng

IITA

~.d

rice IRRI s

other national gene banks '

der aund.storKhung..nsllltt fUr L..ndwlrbchilfl. Fed.r.1 ...publlc: of G.rm.n,. 5 IntemdOMI R~ R....n:h Institute, to. aeno" Philippine, I PI.nt G.rmpa..m Inatttute, BllrI, ....)' 7 Nenon.1 prognms In developing countries with 'aclllties to.tor. dupUcele ..mpt. .

LIFE HISTORY OF AGERM PLASM ACCESSION AT IITA

Temporary seed storage

Multiplication in pots or field

Registration of sample with descriptive data recorded at time of collectio n

After multiplication, assigned permanent accession number

Donation

Post-entry observation by Nigeria Federal Department of Agriculture,

Plant Quarantine

Genetic Resources Un it of IITA

Service, Ibadan ./

Explorationl

Collection

Duplicate sets given to collaborating national programs

Seed is dried and prepared for storage

Placed in base collection for long-term storage and regeneration

-_.-.-,

Stored in active collection for evaluation, distribution, and further multiplication

Germplasm users:

IITAcrop improvement programs

Seed from active collection is grown out for evaluation and characterization. The following information is recorded in computer data bank:

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Duplicate base collection centers for safe storage

- Agrobotanical data taken at time of field and laboratory evaluation - Storage data (quantity, location, date of entry, percent of viability) Data on resistance to diseases, pests, and environmental stresses and any other information that reaches IITA on any given plant is added to its file . All information is made available on request and is used in selection of germplasm samples.

Researchers , plant breeders, agricultural workers worldwide

Plants are grown. Growers provide feedback information to IITA_

Technicians drying seed (or storage

temporary storage, at 15°C and 15% relative humidity. The specimen is multiplied in order to obtain fresh seed , which becomes material for permanent accession. When the new seed has been produced, the specimen receives its permanent accession number preceded by the letter T, for Tropical (to designate IITA), and the first letters 01 the species name. Thus cowpea accessions (Vigna unguiculata) are designated TVu , African rice (Oryza glaberrima) TOg , and Asian rice (0. sativa) TOs. Next, the seed is prepared for storage in two separate collections . Aher harvesting and drying, it is threshed , cleaned , sorted, and fumigated, to kill any pests. About one kilogram of seed of any one variety is placed in a plastic screwtop jar and stored in the active, or working, collection at 5°C and 30-35% relative humidity. Requests for germplasm samples from IITA scientists and researchers around the world are filled from this collection , and when such requests are frequent. the seed is multiplied. Another lot of seed of the same variety , freshly harvested and with viability known to be greater than 90

N. O. Ng, geneticist and head o( the Genetic Resources Unit, checks samples in the base collection storage unU-at·20°C.

percent, is dried to less than 7 percent moisture content in a drying cabinet conditioned at less than 10% relative humidity and 25°C, and then sealed into aluminum cans and stored at -20°C. Under such conditions seeds can remain viable for at least 50 years . This collection , called the base collection, is intended for long-term storage and is the real treasure store of the Unit's genetic resources . Its seed is periodically tested for viability and , if seed viability of any accession drops below 85 percent, it is rejuvenated . Every year thousands of accessions of germplasm are grown out for multiplication and rejuvenation . For example, in 1987, more than 10,000 accessions of germplasm - 4,839 of cowpea , 3,699 of rice , 1,350 of soybeans, 794 of Sambara groundnut, and 100 of miscellaneous legumes - were grown out. Root crop germplasm is stored in vitro in liTA 's tissue culture laboratory by the minimal growth storage method and maintained as living collections in a "field gene bank." The procedure of in vitro conservation method , in brief, involves the development of culture medium and low incubation temperature in order to keep plant growth to a minimum .

SERMPLASM MATERIALS HELD IN THE IlTA SENETIC RESOURCES UNIT AS OF 110-1911 Crop

Species

No. of accessions

Gr8ln~

cowpea rice

maize soybean Sambara ground nut

African yam bean winged bean lablabbaan Kersting's groundnut pigeon paa jack bean sword bean

Vigna ungulculalB wild Vigna Oryza saliva O. glabBrrlma wild Oryza Zaamays Glycine max Vigna subterrsnes Sphenos/yIiB stenocarpa Psophocarpus tetragonolobus Lablab purpuraus Kerstingiella gflOCBrpB

rice baan Mexican yam bean

Csjsnus csjsn Canavalia enslformls Cansvalia gladlalB Vigna radlalB Vigna umbBllalB Pachyrhizus tubBrosus

Jeucaena mucuna gllrlcldla

LeUCBena leucocephala Mucuna prurlens Gllrlcldla seplum

sweet potato yam plantain

Ipomoea balBlBs Dloscoraa sp. Musssp. Manlhot escu/enlB wild Manlhot

green gram

cassava Total

----

15,100 560

8,901 2,557 183 5,000' 1,448 1,996 123 27 28

7 8 5 4 100 1 3

3 4

1,000 1,000

250 2,000 48

40,310

MaI~ tnedllIf ""- de짜eIoped by IfTA'. MaIn "-""" ,.,....... -'*" ..., ..... 1Iboue 50,000 tnedlng line. In Ifton.

RooIa. ...,., and plantain _

pr-..cI In 1M ......

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I&boratary GIlt. Roat, Tuber and PWMin t"..,.o...........

Program end In IIeIcII gene .....

19 _ _ _ _ ____

THE IlTA LABORATORY PROCEDURE FOR PRODUCING AND MAINTAINING IN VITRO CULTURES OF ROOT AND TUBER GERMPLASM

Field germplasm

,~ Explant

--,I

t- - - - - -- - -

..... Incubate at Meristems or

Subculture

25-30째C with 4,OO(H;,QOO Lux

node cutti ngs

light intensity

I I I I I

I , / Apical bud node cuttings

t- - - -- - -- -- -- - 1-

Store at lower incubation temperature

In vitro planUets

Meristem regenerated

planUets

l L5-20째C

, .. Virus-tested germplasm

Multiplication

, /

evaluation /

_ _ _ _ _ _ 20

International distribution

Field

I I I ' I _ I IVirus indexing /

I I I

RESOURCES FOR ALL TO USE

he Genetic Resources Unit offers training courses in (a) germplasm exploration and collection , (b) seed conservation and gene bank management. and (c) short-term individual and degree-related training . The Unit's own research has recently focused on cowpeas, Bambara groundnuts, and other Vigna and Oryza species. In addition , within the international agricultural research system, the Unit has undertaken collaborative research efforts with IBPGR in Rome , and with national , regional, and international agricultural research

centers . All plant explorations are undertaken in collaboration with the national program of the country in which the exploration takes place. The Unit has recently :

â&#x20AC;˘ provided funding to the National Crop Research Institute of Ghana to explore Vigna and wild Oryza species and evaluate cowpea germplasm for the national breeding program in conjunction with a scientist from the IITA Grain Legume Improvement Program stationed in the country;

• provided funding to the national grain legume research program in Zambia for the evaluation of cowpea germplasm for its breeding program; • provided funding support to national scientists in Burkina Faso for evaluation of Bambara groundnut; • arranged for collection of Bambara groundnut and related wild species for research by the University of Miami (USA) and for collection of Sphenostylis species for research by Cornell University (USA) in Nigeria; • provided logistical support for several Japanese study teams in Nigeria to explore and collect vegetable and rice species; • with IITA's Grain Legume Improvement Program , Rice Research Programme, Root and Tuber Improvement Program, and Virology Unit, evaluated and studied the entire collection of germplasm; • collaborated with scientists in Italy and the United States on wide

A young African scienUst who is aNached to /ITA germplasm specialists receives on-the-job training in gene-bank management.

crosses between cowpeas and wild Vigna and biotechnological innovations, with the aim of transferring desired genes from wild species to cowpea cultivars; • collaborated with IBPGR in plant exploration, plant genetic resources survey, publications on crop descriptors, organizing international workshops , and training.

Rice scientists from around the world observe evaluation 'r;als of rice germplasm from Africa atilTA 's Dnne substation in Nigeria. in a high rainfall agroecolog;cal zone.

SECTION 3

PRACTICAL APPLICATIONS genetic resources conservation unit takes the long view: a large part of its rationale is the security of genes whose usefulness is not yet known . But the useful potential of many genes has already been recognized : exotic germplasm is now supply ing genes for resistance to diseases, pests, and such environmental stresses as drought, heat. cold, and soil toxicity . The well-known successes of IITA crop improvement programs have largely been due to the comprehensiveness of the gene pool on which the scientists can draw for breeding. Through the use of naturally occurring variation in the germplasm available at liT A, scientists have developed :

• cassava varieties resistant to cassava mosaic disease (CMO) and bacterial blight (CBB) ; • maize varieties resistant to the streak virus; • extra-early and multiple diseaseresistant cowpeas; • high-yielding, water-Iogg ingresistant, and long-grained rice ; • sweet potato resistant to virus

disease com plex and the sweet potato weevil ; â&#x20AC;˘ long-grained rice resistant to rice yellow mottle virus (RYMV).

Cowpeas and rice Cultivated germ plasm of both cowpeas and rice has been explored and collected quite extensively. The emphasis is shifting somewhat to collecting the germplasm of the ir wild species, as well as cultivated germplasm in remote areas or countries where they have not yet been collected adequately. The Genetic Resources Unit has initiated interspecific crosses between cowpea and wild Vigna with several aims: transferring certain genes (for resistance to pod borer and pod sucking bugs) from wild Vigna to cultivated cowpea ; studying the evolutionary relationship between cowpea and other Vigna species; and reviewing the taxonomy of African Vigna species. Currently extensive crosses are being made between cowpea and V. vexillata, and the studies of histology of fertilization and embryo development following the cross are under way.

Collections of African rice will also be studied more intensively . The particular form will be their genetic differentiation, usefulness in crop improvement and the genetic basis of the immunity to rice yellow mottle virus in O. g/aberrima with the aim of transferring this resistant gene to 0. sativa. Another plan is to form a subset of the rice and cowpeas collections that would represent the diversity of the whole collections of each crop. This subset (much smaller than the complete collection) will be used more intensively in screening programs.

Soybeans

Yams

The genetic resources of the soybeans maintained in the Unit are selected for and specifically useful to breeding the crop for the tropics . The Unit will continue to preserve these collections and to distribute them on request.

In view of the importance of yams in West Africa, and since IITA has the CGIAR world mandate for the crop, IITA scientists will continue to maintain and expand its yam germplasm collection as part of its plan. In future , greater emphasis will be given to the characterization , evaluation, documentation and study of the genetic resources of this crop with the intention of making it more accessible to and usable by researchers .

COWPEAS The cowpea is an indigenous African legume that was probably domesticated in the West African savanna and rain forest transition zone. An important source of protein for many people in the sem i-arid and subhumid tropics of Africa , it is grown mostly in subsistence farming systems, frequently in mixed croppi ng with sorghum. millet, maize , and other crops , for seeds, vegetab les, fodder, ground cover, and green manure. Unfortunately, the cowpea is usually susceptible to a wide range of pests and diseases, But as some exceptions exist, it is vital to keep the genetic material of

those few disease-resistant and pestresistant varieties. With over 15,000 accessions from over 100 countries around the world, the Genetic Resources Unit has the largest cowpea collection in the world . Several African national agricultura l research programs have devoted much effort to improving this important food resource, but their efforts have usually been restricted to specific regions with in their national boundaries. Before research programs of international scope were established, these national programs lacked access to the diverse germplasm

resources scattered throughout Africa and other parts of the world . Even so, some national programs managed to make progress. But in some cases , all the work of assembling collections of cowpea germplasm was lost because the program did not have the facilit ies and resources to maintain them . For cowpeas , the Unit's data base records 11 passport data and 29 agrobotanical characters , 15 pest and disease characteristics , and 2 nutritional elements. Duplicate samples are kept at the USA National Seed Storage Laboratory in Fort Collins, Colorado. Disease can cause crop losses of 70 percent in cowpeas. Insect pests, such as aphids, leaf hoppers, and beetles, can completely wipe out a crop at any stage of growth--or in storage. Intensive screening of IITA's cowpea accessions has contributed to the d iscovery of cowpea路 varieties w ith resistance to insect pests and many major diseases.

YAMS There are six major cultivated yam (Dioscorea) species around the tropics . Different yam species originated and were domesticated in three of the world 's tropical regions: Southeast Asia (D. alata and D. esculenta). tropical America (D. trifida) , and West Africa (D. rotundata , D. cayenensis and D. dumetorum) . Yams are of inestimable importance, both culturally and nutritionally. in West Africa , which produces from 20 to 25 million tons per year or about 90 percent of the world's crop . Nigeria alone produces about 70 percent of the world total. At IITA. which has been assigned the world mandate for yams by CGIAR. part

of the 1.000 accessions of yam germplasm are conserved in vitro by the tissue culture laboratory and in field gene banks. The Genetic Resources Unit's data bank documents over 40 agrobotanical characteristics of the crop . liT A and the National Root Crop Research Institute of Nigeria have developed a cheap and reliable system . the so-called "minisett technology ," for rapid seed yam production. which can accelerate the breeding cycle and overcome the shortage of planting materials at farm level. Through the evaluation of germplasm. promising varieties of yams that are high-yielding and fairly resistant to necrotic diseases have been identified.

RICE Rice is usually associated with Asia, but five wild species of rice (Oryza barthii, O. longistaminata. 0. brachyantha, 0. eichingeri, and O. punctata) and the West African domesticated rice (0. glaberrima) originated in Africa . In addition, the Asian domesticated rice (0. sativa) has been present in Africa for about 2,000 years, and the many land races that have developed from it have contributed greatly to the genetic diversity of rice in Africa. Some pests and diseases in Africa are different from those in other parts of the world . African germplasm may be better able to resist some of them and environmental stresses than Asian germplasm. The potential of some species has not yet been exploited . For example, the red-grained 0. glaberrima has proved in limited trials to have the potential for yielding as much as some commercial varieties , and yet there has been no concerted effort toward improvement of the species. African farmers , who prefer 0. sativa, often treat the native rice like a weed . These varieties are at risk of being eroded. The Genetic Resources Unit's data base records 12 passport data and 44 agrobotanical characters for its rice varieties . Whereas the International Rice Research Institute (lRRI) , at Los Banos, Philippines, has the world mandate for rice , IITA has responsibility for conserving and improving the African species and varieties . The IITA collection amounts to 11,641 accessions. The two institutions work in close cooperation , with IRRI holding duplicate sets of African rice germ plasm holdings. Duplicates of some varieties are also kept at the National Institute of Agrobiological Resources in Tsukuba, Japan .

BAMBARA

GROUNDNUT The Sambara groundnut (Vigna 5ubterranea) is an indigenous and extremely nutritious West African legume that ranks third in importance among African pulses, after cow peas and peanuts. It is cultivated extensively from Senegal to Kenya and from the Sahara to South Africa - and has been reported growing in Brazil and Indonesia as well. It has potential importance for drought路prone areas with poor soils. But very little research 'on the selection and improvement of this popular crop has been done. Us germplasm is being seriously eroded and many earlier collections have been lost. Sambara groundnut is not in the IITA mandate. but at present the Genetic Resources Unit, which holds about 2,000 accessions of Sambara ground nut. is the

only center in the world preserving the crop's germplasm. A grant from GTZ has assisted evaluation, characterization. and documentation. The Unit has distributed 953 samples of Bambara groundnut germplasm to national agricultural research institutions. But before evaluation and cha racterization could be undertaken , a descriptor list and descriptor stages for the species had to be painstakingly developed. That list was finally established at the end of 1985 and serves as a standard guideline for all those who wish to characterize and evaluate 8ambara groundnut varieties. The descriptors consist of 29 passport data and 49 agrobotanical characters , as well as several other data on pests and diseases.

Extracts of descriptors tabulated in the lITA Cowpea Germplasm Catalog: an example of published information categories of a priority crop

479

:; N U

480

481

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482

- '"z ~ Q,.

co:

483

484

485

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"'::0 "'< ~= x< -...l "'<

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~: x<

-...l

-.(

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:( N

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USA

USA NIGIA

USA

486

487

TVu Number

, co:

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NIGIA NIGIA

O...l Q,....l Q,.-

2 Pedigree

USA

3 Origin

5 First Flower

6 Fi",t Ripe Pod

10 Plant Growth Habit

13 Detenninancy

23 Shape

29 Testa Texture

30 Size

37 Bacterial Blight

40 Virus

41 Anthracnose

43 Flower

45 Total Pods

46 Good Pods

....•

...= ~

...is.

No./Peduncle

[ C

.08

.09

.13

.09

.10

.11

.12

4.11

4.51

4.83

3.99

3.94

3.83

4.32

i I ..~Ii... ~

49 Sulfur Percent

SO Nitrogen Percent

:: •2 n

ir:

Request form for obtaining germplasm from lIT A I

I I I I I I I I I I I I I I I I I I I I I I I I I I I I

Seed samples requested:

Specific requirements:

What is the purpose of this request?

Where will the sample be grown?

Name Title Organization Address Country

Send your requesl on a copy of this form to:

Genetic Resources Unit International Ins titute of Tropical Agriculture PMB 5320. Oyo Road Ibadan, Nigeria

Genetic Resources Unit (!ITA) c/o Lambourn and Co., Ltd. Carolyn House 26 Dingwall Road Croydon CR9 3EE, England

International Institute of Tropical Agriculture PMB 5320, Dyo Road - Ibadan, Nigeria Telephone : (22) 400300-400314 Telex : TDS IBA NG 20311 (Box 015) 31417 TRDBIB NG TRDPFOUND IKEJA Cable: Facsimile: 234-1- 669185

PrOJec t, design . and productio n by

Alphabyte, Viele Allentlno

42, 001 53 Rome, Italy' Tel. 39-&575-9839