Genetic integrity of ex situ Coffea collections are being compromised due to cross pollination by other species
Contributed by Sarada Krishnan @KrishnanSarada
Africa, Agriculture, Asian-American, Biodiversity, Community ecology, Conservation, DNA, Ecology, Field, Forest, Genes, Genetic material, Lab, Molecular biology, Observational, Plants, Race/ethnicity, Theory/Computational, Woman
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Krishnan, Sarada, T. Ranker, A. P. Davis, and J.J. Rakotomalala. 2013. An assessment of the genetic integrity of ex situ germplasm collections of three endangered species of Coffea from Madagascar: implications for the management of field germplasm collections. Genetic Resources and Crop Evolution. 60:1021-1036. DOI: 10.1007/s10722-012-9898-3. link
Slide 1: Researcher’s Background
Sarada is the Director of Horticulture and Center for Global Initiatives at Denver Botanic Gardens. Her research focuses on the conservation of coffee genetic resources.
PB: Why did you become a biologist?
SK: I have always been interested in plants and nature. With a family background in Agriculture, specifically coffee farming, I pursued a degree in horticulture followed by coffee research.
PB: What is your favorite part about your job?
SK: Being able to contribute to the conservation of genetic resources of one of our important global crops.
PB: What obstacles have you overcome to get where you are?
SK: Even though there are many women in the field of Horticulture, it is still predominantly a male dominated field, especially in leadership roles. After graduating with my Masters in the early 1990s, while looking for a job, I realized that my name was an issue. I would drop off my resume at various greenhouses (this was pre-internet and cell phones) and many would never call me back. I realized that my name was an issue when one woman blatantly said that she did not call me because she could not pronounce my name. Over time, with hard work, I have been able to overcome this and am now well recognized in the field of coffee genetic resources and conservation.
PB: What advice do you have for aspiring biologists?
SK: Follow your passion and be patient and persistent and you will be able to achieve what you want. Dream big!
PB: Do you feel that any dimension of your identity is invisible or under-represented/marginalized in STEM?
SK: As mentioned earlier, it is always a struggle when you have a foreign sounding name that is hard to pronounce. In addition, women are underrepresented in STEM fields. Many a times, I have been in meetings where I am the only female among a group of white males, and that too a female of color.
Slide 2: Research Overview
Take home message of study
For my doctoral research (which I did a little later in life), I studied the genetic diversity of four Coffea spp. endemic to Madagascar. I I compared the genetic diversity of these fours species conserved in the ex situ field genebank with those in situ growing in the forests. Genetic diversity studies of three of the four species showed higher diversity in ex situ field genebank collections compared to plants in situ in their natural forests. This higher diversity could be a result of loss of plants in the wild since the collections were made in the 1960s as well as the genetic contamination of ex situ collections due to cross pollination between species, thereby compromising the genetic integrity of the collections.
Genetic diversity studies were conducted using six microsatellite (SSR) markers. The plant on the right is Coffea montis-sacri, a critically endangered species. When collecting this species in situ at its native range in Mt. Vatovavy in the eastern rainforests of Madagascar, our expedition was able to locate only six plants existing in the wild in 2007.
Slide 3: Key Research Points
Results of this study showed that open pollinated seed propagation in the field genebank is unambiguously contaminated by pollen from other species of Coffea, and that the level of extra species cross-fertilization was variable depending on the species sampled. The results suggest that some offspring of both species, C. kianjavatensis (5.56%) and C. montis-sacri (33.33%), were a result of interspecific hybridization, which has serious implications concerning the value and future management of ex situ Coffea germplasm collections.
Even though Madagascan species are not cultivated, as wild relatives of cultivated coffee, it is important to conserve these important genetic resources. In light of climate change and other environmental threats, we may have to turn to these wild species for important traits such as drought tolerance, disease resistance etc. that can be tapped into for coffee breeding programs to ensure the future sustainability of our cultivated coffee. Coffee cultivation contributes to the livelihoods of many small-holder farmers in many developing countries.