出 处:《生物多样性》2024年第6期47-55,共9页Biodiversity Science
基 金:国家自然科学基金(32160055,32360059);甘肃省自然科学基金(21JR7RA140)。
摘 要:两型闭花受精现象是指在植物个体发育的不同时期或不同部位会形成两种形态完全不同的花,即异花传粉的开放花(chasmogamous flower,CH)与自花传粉的闭锁花(cleistogamous flower,CL)。维西堇菜(Viola monbeigii)与裂叶堇菜(V.dissecta)在早春时期为CH花,夏季为CL花,光周期可能调控着两种花型的发育。本研究对维西堇菜和裂叶堇菜不同光周期下的花型进行了形态观察与统计,以探究光周期对两种花型发育的调控作用,并阐明两种花型不同发育阶段的主要形态差异。结果表明:维西堇菜和裂叶堇菜的CH和CL花的差异主要体现在花瓣与雄蕊的大小与数量、蜜腺体的有无、花丝长短、柱头有无弯曲等方面。CH花5个花瓣,下花瓣有一长距,5枚雄蕊,花丝很短,2枚雄蕊背部的蜜腺体伸入下花瓣形成的距中,雌蕊花柱直立并高于雄蕊;CL花雄蕊2枚,花丝较长,无蜜腺体,其余雄蕊与5个花瓣均为原基状,雌蕊的柱头通常弯向2枚发育最好的雄蕊。另外存在着花瓣与雄蕊数量介于CH与CL花之间的过渡闭锁花(intermediate cleistogamous flower,inCL),其花部特征与闭锁花一样,花萼一直包裹着其他3轮花器官。中短日照(12 h及以下光照)下诱导的花芽大部分为CH花,长日照(16 h光照)下诱导的大部分花芽为完全CL花。两个物种的CH花与CL花在4轮花器官原基形成后出现明显的形态差异,并随着花芽发育的成熟,形态差异更加明显。本研究揭示了光周期对维西堇菜与裂叶堇菜CH和CL花发育的调控作用,阐明了CH与CL花出现明显差异的时期与具体形态差异,为堇菜属两型闭花受精适应性进化研究提供了理论依据。Aims:Dimorphic cleistogamy,characterized by the coexistence of open chasmogamous(CH)and closed cleistogamous(CL)flowers within a single plant,presents a unique mating system.Viola monbeigii and V.dissecta exhibit this dimorphic cleistogamy,producing CH flowers in early spring and CL flowers in summer and early autumn.However,the role of photoperiods in regulating the development of CH and CL flowers in these Viola species remains unclear.Therefore,this study aims to investigate the influence of photoperiods on the development of CH and CL flowers in Viola monbeigii and V.dissecta.Additionally,the study seeks to elucidate the main morphological distinctions corresponding to the different development stages of CH and CL flowers in these two Viola species.Methods:Viola monbeigii and V.dissecta were cultivated under controlled photoperiods of 10,12,and 16 hours.The morphology of flower buds was meticulously observed using a stereomicroscope.Flowering days and the proportions of flowering induction,chasmogamous(CH),intermediate cleistogamous(inCL),and cleistogamous(CL)flowers were assessed under each of the 10,12,and 16-hour photoperiods.Additionally,a stereomicroscope was employed to discern the principal morphological disparities corresponding to the different developmental stages of the CH and CL flowers in both Viola species.Results:(1)Both V.monbeigii and V.dissecta exhibited the development of both chasmogamous(CH)and cleistogamous(CL)flowers.Key morphological disparities between CH and CL flowers included variations in petals and stamen size and number,the presence or absence of nectaries,filament length,and stigma curvature.CH flowers typically featured five large,showy petals with a spur at the base of the lowest petal;five stamens formed a cone surrounding the pistil,and nectar glands on the lowest two stamens that noticeably extended into the spur formed by the lowest petal.The pistil was erect and higher than the stamens.In contrast,CL flowers possessed two stamens without nectar glands,longer filaments,an
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