Abstract Detail

Molecular Ecology

Mead, Alayna [1], Medeiros, Camila [2], Sack, Lawren [3], Sork, Victoria  [4].

Oak drought tolerance traits and climatic niches determine their transcriptomic responses to leaf drying.

Oak (Quercus) species have adapted to a wide range of climates, and in many cases different lineages have adapted to the same climates in parallel. To investigate the genomic basis of adaptation to drought stress, we compared the transcriptomic response to drought and drought-related functional and ecophysiological traits among six California oak species. Species pairs were selected from the three sections of oaks present in California and from contrasting mesic and xeric climates to test the extent to which their responses were due to phylogenetic history or the climate niche of the species. Branches sampled from adult individuals of each species growing in Rancho Santa Ana Botanic Garden in Claremont, CA, were subjected to an experimental leaf drying treatment. We collected leaves and later extracted the RNA to characterize their gene expression response and also measured several drought-related traits. We found that species generally responded to the drying treatment with unique genes, but that species sharing the most drying-responsive genes were from different sections. Notably, the two species with the most similarities in their gene expression response were distantly related, but shared similar traits and climatic niches: both are deciduous and relatively drought sensitive. Additionally, species that were more drought tolerant (measured as having a lower turgor loss point) responded to drying stress with fewer genes. Our findings indicate that traits of more drought-tolerant species allow them to survive drought conditions without significantly altering their gene expression, while drought-sensitive species must respond to drought through plasticity mediated by gene expression changes. This study provides evidence that the oak response to drought is shaped more by their climate history than by phylogeny. Low parallelism in the gene expression response even among similar species suggests that there are multiple mechanisms through which drought response can evolve. The range of genes that these oak species use to respond to drying stress may have allowed species within different sections to adapt to similar climates independently.

1 - University of California, Los Angeles, Ecology and Evolutionary Biology, 4140 Terasaki Life Sciences Building, 610 Charles E. Young Drive East, Los Angeles, CA, 90095, US
2 - University of California, Los Angeles, Ecology and Evolutionary Biology
3 - 621 Charles E. Young Drive South, Los Angeles, CA, 90095, United States
4 - UCLA, ECOL & EVOL BIOL, Box 957239 , Los Angeles, CA, 90095, United States

Gene expression
parallel evolution

Presentation Type: Oral Paper
Session: MOL1, Molecular Ecology
Location: Virtual/Virtual
Date: Tuesday, July 28th, 2020
Time: 1:30 PM
Number: MOL1005
Abstract ID:843
Candidate for Awards:None

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