Evolutionary breakdown of distyly to homostyly is accompanied by reductions of floral scent in Primula oreodoxa  

作　　者：Gui Zeng Spencer C.H.Barrett Shuai Yuan Dian-Xiang Zhang 

机构地区：[1]Key Laboratory of Plant Resources Conservation and Sustainable Utilization,South China Botanical Garden,Chinese Academy of Sciences,Guangzhou 510650,China [2]University of Chinese Academy of Sciences,Beijing 100049,China [3]Department of Ecology and Evolutionary Biology,University of Toronto,Toronto,Ontario M5S 3B2,Canada

出　　处：《Journal of Systematics and Evolution》2023年第3期518-529,共12页植物分类学报（英文版）

基　　金：This research was funded by the National Natural Science Foundation of China(Grant Nos.31800314 and U160323);a Discovery Grant from the Natural Sciences and Engineering Research Council of Canada to SCHB.

摘　　要：Reproductive traits that function in pollinator attraction may be reduced or lost during evolutionary transitions from outcrossing to selfing.Although floral scent plays an important role in attracting pollinators in outcrossing species,few studies have investigated associations between floral scent variation and intraspecific mating system transitions.The breakdown of distyly to homostyly represents a classic example of a shift from outcrossing to selfing and provides an opportunity to test whether floral fragrances have become reduced and/or changed in composition with increased selfing.Here,we evaluate this hypothesis by quantifying floral volatiles using gas chromatography-mass spectrometry in two distylous and four homostylous populations of Primula oreodoxa Franchet,a perennial herb from SW China.Our analysis revealed significant variation of volatile organic compounds(VOCs)among populations of P.oreodoxa.Although there was no difference in VOCs between floral morphs in distylous populations as predicted,we detected a substantial reduction in VOC emissions and the average number of scent compounds in homostylous compared with distylous populations.A total of 12 compounds,mainly monoterpenoids and sesquiterpenoids,distinguished homostylous and distylous morphs;of these,(E)-β-ocimene was the most important in contributing to the difference in volatiles,with significantly lower emissions in homostyles.Our findings support the hypothesis that the transition from outcrossing to selfing is accompanied by the loss of floral volatiles.The modification to floral fragrances in P.oreodoxa associated with mating system change might occur because high selfing rates in homostylous populations result in relaxed selection for floral attractiveness.

关 键 词：floral scent HETEROSTYLY homostyly mating system Primula oreodoxa 

分 类 号：Q94[生物学—植物学]