Conserving Diversity in Crabapples

By Na Wei, PhD, Scientist

Crabapples are popular ornamental trees. They feed pollinators and harbor essential genetic diversity for modern apple breeding. Learn more about the genetic diversity, microbiome diversity and pollinator diversity of crabapples at Holden.

Crabapple genetic diversity

Crabapples are important members of the rose family. Many crabapples are cultivated as ornamental trees or rootstocks. The Holden Arboretum hosts a valuable collection of crabapple cultivars and wild species, as part of the long-term National Crabapple Evaluation Project (NCEP) plots established since the 1980s. There are 40 different crabapple cultivars and species in the NCEP plot at Holden. Many of these crabapples are museum trees now, which are important genetic resources that are only present at botanical gardens and arboreta.

Using molecular tools, we provide the first demonstration of the genetic diversity in our crabapple collections. Holden’s 2022 summer research intern, Maris Hollowell, worked with Dr. Wei to extract DNA from these crabapples and decipher their genetic relatedness and diversity. Maris presented this work at the 2022 SEARCH symposium. The research is supported by a Global Botanic Garden Fund from the Botanic Gardens Conservation International for the purpose of integrated diversity conservation in crabapples.

Maris Hollowell

Crabapple microbiome diversity

Crabapples host diverse microbes. These microbes influence tree health and disease resistance. Holden’s 2021 Norweb Fellow, Jessica LaBella, isolated fungi from crabapple leaves and found that the apple scab fungus is very common in our crabapple collections. Supported by a Corliss Knapp Engle Scholarship in Horticulture from the Garden Club of America, LaBella presented the work at the 2021 SEARCH symposium. We also found that some crabapples are more resistant than others. We are evaluating the microbiomes of resistant vs. susceptible crabapples using DNA sequencing. This assessment is a critical step for our goal to harness microbiomes for disease resistance in crabapples.

Crabapple pollinator diversity

Flowering crabapples are essential food resources for pollinators. We observe pollinators that visit 93 crabapple trees at Holden Arboretum and 214 crabapple trees at Secrest Arboretum. We find that crabapples attract diverse pollinators, including honeybees, bumblebees, carpenter bees, mining bees, sweat bees, other bees, wasps, flies and butterflies. Bees are the dominant pollinators of crabapples, especially honeybees. Pollinators prefer crabapples that have a lot of flowers — especially white flowers compared to other flower colors.

Holden’s 2020 summer research intern, Miyauna Incarnato, conducted pollinator observations and presented the work at the 2020 SEARCH symposium. We are continuing our crabapple pollinator observations every year during the peak flowering season from late April to early May. This work is run by pollinator volunteers at Holden. Our 2022 crabapple pollinator team was lucky to have Dave Marble, Jennifer Ault, Patricia Collier and Trish Hannington. We are looking forward to working with more volunteers who are interested in pollinators.

“Crabapples are important for pollinators and humans,” says Wei. “We hope that our research on crabapples will benefit our society by training young scientists and advance our knowledge and effort in conserving biodiversity.”

Meet The Staff

Na Wei, PhD, is a Plant Biologist at Holden. She leads the evolutionary ecology and genomics lab. Her research program seeks to elucidate the mechanisms that influence plant adaptation to rapid environmental change. Her research tackles these grand questions using interdisciplinary approaches, integrating plant biology, microbial ecology, pollination biology, evolutionary biology, genetics, and genomics. Na received her PhD in ecology and evolutionary biology from the University of Michigan, Ann Arbor.