Phenology and polyploidy in annual Brachypodium species (Poaceae) along the aridity gradient in Israel  

作　　者：Shira Penner Barak Dror Iris Aviezer Yamit Bar-Lev Ayelet Salman-Minkov Terezie Mandakova Petr Smarda Itay Mayrose Yuval Sapir 

机构地区：[1]Tel Aviv University Botanical Garden,Tel Aviv University,Ramat Aviv,Tel Aviv 69978,Israel [2]School of Plant Sciences and Food Security,Tel Aviv University,Ramat Aviv,Tel Aviv 69978,Israel [3]Central European Institute of Technology(CEITEC),and Faculty of Science,Masaryk University,Brno,CZ-62500,Czech Republic [4]Department of Botany and Zoology,Masaryk University,Brno,CZ-61137,Czech Republic

出　　处：《Journal of Systematics and Evolution》2020年第2期189-199,共11页植物分类学报（英文版）

基　　金：The cytological work was supported by the CEITEC 2020(LQ1601)project.

摘　　要：Local adaptation of plants along environmental gradients provides strong evidence for clinal evolution mediated by natural selection. Plants have developed diverse strategies to mitigate stress, for example, drought escape is a phenological strategy to avoid drought stress, while polyploidy was proposed as a genomic adaptation to stress. Polyploidy as an adaptation to aridity (an environmental parameter integrating temperature and precipitation) was previously documented in annual Brachypodium spp. (Poaceae) in the Western Mediterranean. Here, we examined whether polyploidy or phenology are associated with aridity in annual Brachypodium spp. along the aridity gradient in the Eastern Mediterranean. Using flow cytometry, we determined ploidy levels of plants from natural populations along the Israeli gradient, spanning ～424 km from mesic Mediterranean to extreme desert climates. In a common garden we recorded time of seedling emergence, flowering and senescence. We tested whether the proportion of allotetraploids in the populations and phenological traits were associated with aridity. Contrary to a previous study in the Western Mediterranean, we found no effect of aridity on the proportion of allotetraploids and diploids within populations. Interestingly, phenology was associated with aridity: time of emergence was later, while flowering and senescence were earlier in desert plants. Our results indicate that in the Eastern Mediterranean, adaptation of Brachypodium to aridity is mediated mainly by phenology, rather than ploidy level. Therefore, we suggest that genome duplication is not the main driver of adaptation to environmental stress;rather, phenological change as a drought escape mechanism may be the major adaptation.

关 键 词：ABIOTIC stress adaptation BRACHYPODIUM CLIMATIC gradient POLYPLOIDY 

分 类 号：Q94[生物学—植物学]