盐胁迫下燕麦光合及叶绿素代谢变化研究

Study on Photosynthesis and Chlorophyll Metabolism of Avena sativa L.under Salt Stress

为探究盐胁迫对燕麦叶片叶绿素代谢的影响,揭示盐胁迫对燕麦光合作用通路的抑制作用及其分子机制,采用沙培的方法,Hoagland营养液条件下,给燕麦幼苗施加200 mmol/L NaHCO_(3)胁迫处理,在处理1d、3d、5d、7d时测定叶片叶绿素a(Chla)含量、叶绿素b(Chlb)含量、总叶绿素(TChl)含量、净光合速率(Pn)、蒸腾速率(Tr)、胞间二氧化碳浓度(Ci)、气孔导度(Gs)、原卟啉(IX)含量、镁—原卟啉(Mg-IX)含量、原叶绿素酸酯(PChl)含量及叶绿素代谢途径关键基因表达量。研究发现,盐胁迫降低Chla、Chlb、TChl、IX、Mg-IX、PChl含量,抑制Pn、Tr、Gs,增加Ci,下调叶绿素合成途径关键基因PBGD、Mg-Ch、POR、CLS表达,上调叶绿素降解途径关键基因PAO和PPH。结果表明,盐胁迫可通过下调叶绿素合成途径关键基因PBGD、Mg-Ch、POR、CLS表达,上调叶绿素降解途径关键基因PAO和PPH并减少叶绿素合成前体物质含量影响叶绿素合成,同时降低光合色素含量,抑制燕麦叶片光合作用,促进呼吸作用,抑制蒸腾作用。

In order to explore the effect of salt stress on chlorophyll metabolism of oat leaves and reveal the inhibitory effect of salt stress on photosynthetic pathway of oat and its molecular mechanism,the treatment of 200 mmol/L NaHCO_(3) was added to the seedlings of Oat under the condition of Hoagland nutrition solution and the method of sand culture.After 1 d,3 d,5 d and 7 d treatment,the content of Chla,Chlb,TChl,IX,Mg-IX,PChl and the Pn,Tr,Ci,Gs in Oat leaves were measured.In addition,the relative expression of key genes in the chlorophyll metabolism pathway were studied.The results showed that salt stress decreased the content of Chla,Chlb,TChl,IX,Mg-IX,PChl,and inhibited the Pn,Tr,Gs of the leaves,and increased the Ci in it.RT-qPCR analyze showed that the key genes involved in chlorophyll synthesis pathway(PBGD,Mg-Ch,POR,CLS)were down-regulated under salt stress,and the key genes of chlorophyll degradation(PAO and PPH)were up-regulated.In conclusion,salt stress can down-regulate the expression of PBGD,Mg-Ch,POR,CLS,up-regulate PAO and PPH,reduce the content of precursors of chlorophyll synthesis,and reduce the content of photosynthetic pigment,inhibit photosynthesis,promote respiration and inhibit transpiration of Oat leaves.