两种不同生境苦苣苔科植物的复苏特性及其对水分的光合和生理响应

复苏植物可以耐受极度干旱的环境,脱水至10％相对水分含量后仍然可以复苏.苦苣苔科植物包含有较多复苏植物,不同类群的复苏机理可能存在差异.该文选择分布在亚热带和温带石灰岩地区的锈色蛛毛苣苔(Paraboea rufescens)和心叶马铃苣苔(Oreocharis cordatula)两种苦苣苔科植物,并对这两个物种的叶...

Resurrection characteristics, photosynthetic and physiological response to dehydration and rehydration of two species in Gesneriaceae with different habitats

Resurrection plants usually grow in extreme habitats and have the capacity to survive from lower relative water content to 10%.There are many resurrection plants in family Gesneriaceae,and the resuscitating mechanism of different species may be different.In order to investigate whether the two species have different resurrection characteristics and physiological mechanisms in response to drought,two species of Gesneriaceae,Paraboea rufescens and Oreocharis cordatula,which are distributed in subtropical and temperate limestone areas respectively,were selected in this study.Their leaves were dehydrated for 1,2 and 3 d respectively,and then rehydrated for 1 day.The leaf morphology,relative water content(RWC),photosynthetic activity,photosynthetic pigments,membrane integrity and osmotic adjustment substances during different dehydration and rehydration treatments were detected and analyzed.The results were as follows:(1)The leaf discs of Paraboea rufescens folded inward after dehydration,and the leaf upper epidermis was completely wrapped after dehydrated for two days,and the chlorophyll fluorescence parameter F_v/F_m,which characterized the maximum photosynthetic potential,was inhibited;Comparatively,the leaf discs of Oreocharis cordatula shrunk slightly,maintained the F_v/F_mlevel,and had higher photoprotection abilityY(NPQ)];The leaf discs of both species spread out and the F_v/F_mrecovered following rewatered.(2)After two days of dehydration,the RWC of the two species decreased to about 5%,the relative electricity conductivities(REC)increased to 51.8%and 56.2%respectively,and the contents of soluble sugar increased significantly;During the following rewatered,RWC,REC and soluble sugar all recovered to the control level.(3)After further dehydration for three days,RWC of leaf discs of two species reached about 1.5%,the conductivity increased to about 95%after rehydration,and the F_v/F_mdisappeared.(4)Chlorophyll a+b contents of Paraboea rufescens decreased by 50%during resuscitable dehydration and rehydration,while Oreocharis cordatula remained basically unchanged,which indicated that both of them were homoiochlorophyllous desiccation tolerance species and could quickly resume photosynthesis after rehydration following dehydration;During dehydration and rehydration,the contents of malonialdehyde(MDA)had no significant change,and remained extremely low level,which indicated two species could keep their membrane lipids from being oxidized under extreme drought conditions.To sum up,these two species can survive from dehydration to lower level of 5%RWC,therefore,they are both resurrection plants.Under severe dehydration,Paraboea rufescens can avoid the damage from excessive light absorption by curling its leaves;however,Oreocharis cordatula can spread the excessive energy by heat dissipation through photoprotection of PSⅡ,thus protecting its photosynthesis organs.