硫化氢信号在谷子响应镉胁迫中的生理作用

发布时间：2018-06-20 20:17

本文选题：硫化氢 + 谷子　；参考：《山西大学》2016年博士论文

【摘要】：硫化氢(Hydrogen sulfide, H2S)之前一直被认为是有毒的气体。继一氧化氮和一氧化碳之后,人们发现H2S也可作为气体信号分子行使生理功能。气体信号分子在动植物中起着非常重要的生理调节作用。近年来,植物内源H2S的多种生理生化功能逐步被证明,譬如,种子萌发、根器官的生成、生长与发育、光合作用、气孔运动、细胞程序性死亡等生理过程中都发现H2S的参与；另外H2S参与植物对多种生物胁迫与非生物胁迫的响应,如干旱胁迫、渗透胁迫、重金属胁迫和真菌等。本论文主要研究镉(Cadmium, Cd)办迫下谷子(Setaria italica)幼苗体内H2S产生和变化及外源H2S对Cd胁迫下谷子幼苗生长的影响,利用药理学、生物化学和生理学的试验方法进行多层次的探讨,以深入了解谷子响应Cd胁迫过程中H2S的生理功能与作用机制。主要研究结果如下：1.Cd胁迫抑制谷子幼苗生长,株高和根长显著降低；诱导大量的过氧化氢(H2O2)和丙二醛(MDA)的产生,造成叶片中叶绿素含量的减少和电解质渗漏(EL)的增加。随着幼苗受到胁迫程度的增加,植物体内超氧化物歧化酶、抗坏血酸过氧化物酶、过氧物酶和过氧化氢酶等抗氧化酶的活性升高,以应对H2O2的积累。2.在Cd胁迫条件下,谷子内源H2S含量和H2S产率都升高,表明二者之间存在着紧密联系。外源H2S预处理可增强谷子幼苗的净光合速率、蒸腾速率和气孔导度,进而增强光合作用；减少EL和H2O2含量；抑制Cd诱导的NADPH氧化酶活性的升高及编码基因rboh D和rboh F的表达上调；同时增强金属硫蛋白编码基因MT3和MT2A的转录水平,以缓解体内Cd引起的毒性。3.谷子幼苗响应Cd胁迫时,体内的H2S和脯氨酸(Pro)的含量升高。外源Pro处理可减少Cd诱导的H2O2和MDA含量的增加。在Cd胁迫下,H2S可增加谷子幼苗Pro的积累,这是通过上调P5CR基因的表达和下调PDH基因表达,继而增强P5CR的活性和抑制PDH的活性来实现的。进一步研究发现Cd诱导的Pro积累可以被外源H2S供体硫氢化钠(NaHS)预处理所增强,被H2S的合成抑制剂羟胺(HA)、氨基氧乙酸、丙酮酸钾和清除剂次牛磺酸预处理所抑制。外源H2S和Pro协同处理可以缓解Cd胁迫对谷子幼苗的损害,恢复其叶绿素浓度,增强气孔开度和减少体内H202含量的积累。4.在Cd胁迫条件下,谷子幼苗的可溶性糖和蛋白含量降低,ATPase酶活性(Ca2+-ATPase、Mg2+-ATPase、H+-ATPase)被抑制,P1B-ATPase转运家族HMAs基因表达升高；H2S预处理可增加可溶性糖的含量,提高3种ATPase酶的活性,上调HMA1和HMA2的表达,下调HMA3的表达,从而使进入细胞内的Cd区室化到液泡,抑制Cd向地上部分转移,进而起到缓解Cd毒性的作用。5.外源茉莉酸甲酯(MeJA)预处理谷子幼苗可以增加体内H2S含量,并可明显缓解谷子根部由Cd引起的O2·-、H2O2和MDA浓度的增加以及缓解根生长的抑制。MeJA降低Cd诱导的SiNRAMPl和SiNRAMP6的转录水平的升高,进而减少根对Cd的吸收；Cd上调转运蛋白编码基因MTP1, MTP12, CAX2, HMA3和ZIP4的表达,而MeJA增强MTPs和CAX2的功能,使Cd离子进入液泡起到解毒作用。H2S的合成抑制剂HA和H2S供体NaHS可影响MeJA的调节作用,由此发现H2S参与MeJA缓解Cd胁迫的过程。综上所述：Cd胁迫条件下,H2S、Pro和MeJA三种非生物胁迫应答信号分子协同作用,强化ROS清除系统的活力,减少ROS和MDA的浓度,降低谷子根对Cd的吸收,最终提高植物的Cd耐受性。全文阐述了Cd胁迫过程中谷子体内H2S参与的信号通路及其应对Cd胁迫的生理机制；证明了Cd胁迫过程中H2S的信号作用；明确了在缓解Cd胁迫过程中Pro和H2S以及MeJA和H2S所存在的关系；研究了H2S通过调节P1B-ATPase转运家族HMAs从而提高谷子的Cd耐受。为H2S在植物体内参与Cd耐受信号网络提供更多信息。
[Abstract]:Hydrogen sulfide ( H2S ) has been regarded as a poisonous gas before hydrogen sulfide ( H2S ) . After nitric oxide and carbon monoxide , it has been found that H2S can also act as a gas signal molecule . Gas signal molecules play a very important physiological regulation role in plant and plant . In recent years , many physiological and biochemical functions of endogenous H2S in plants have been proved , such as seed germination , root organ formation , growth and development , photosynthesis , stomatal movement , cell procedural death and other physiological processes .
In this paper , the effects of H2S production and change and exogenous H _ 2S on the growth of millet seedlings under Cd stress were studied by means of pharmacological , biochemical and physiological methods . The results were as follows : 1 . Cd stress inhibited the growth , plant height and root length of millet seedlings .
The activity of antioxidant enzymes such as superoxide dismutase ( SOD ) , ascorbate peroxidase ( SOD ) , peroxidase ( peroxidase ) and catalase ( H _ 2O _ 2 ) in the leaves of the seedlings increased with the increase of the degree of stress .
reducing the content of EL and H2O2 ;
the increase of the activity of NADPH oxidase induced by Cd and the up - regulation of the coding gene rboh D and rboh F were inhibited ;
In response to Cd stress , the content of H 2 + - ATPase , Mg 2 + - ATPase , H + - ATPase in the seedlings of millet seedlings decreased , and the expression of ATPase activity ( Ca2 + - ATPase , Mg2 + - ATPase , H + - ATPase ) was inhibited .
The pretreatment of H2S can increase the content of soluble sugar , increase the activity of three ATPase enzymes , up - regulate the expression of HMA1 and HMA2 , regulate the expression of HMA3 and decrease the expression of HMA3 .
In conclusion , it is suggested that H2S , Pro and MeJA can affect MeJA ' s regulation by enhancing the function of MTPs , CAX2 , HMA3 and ZIP4 . In conclusion , the synthesis inhibitor HA and H2S donor NaHS of H2S can influence the regulation of MeJA . In conclusion , it is found that H2S , Pro and MeJA can play a role in reducing Cd stress .
The signal effect of H2S in Cd stress process is proved .
The relationship between Pro and H2S and MeJA and H2S in the process of Cd stress is clarified .
In this paper , we have studied the regulation of HMAs in the P1B - ATPase transport family to improve the Cd tolerance of the grain . More information is provided for the participation of H2S in the Cd tolerant signal network in plants .
【学位授予单位】：山西大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S515

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