水稻剑叶衰老过程中内源IAA的轭合态变化及其氮素调控效应  

Senescence-specific Changes in Endogenous IAA Content and Its Conjugated Status in Rice Flag Leaf as Affected by Nitrogen Level

作　　者：赵华[1,2] 王复标[2] 韩展誉 SHAMSU-ADO zakari 李兆伟[2] 潘刚[2] 程方民[2] ZHAO Hua;WANG Fubiao;HAN Zhanyu;SHAMSU-ADO zakari;LI Zhaowei;PAN Gang;CHENG Fangmin(Jinhua Polytechnic,Jinhua 321017,China;College of Agriculture and Biotechnology,Zhejiang University,Hangzhou 310058,China)

机构地区：[1]金华职业技术学院,浙江金华321017 [2]浙江大学农业与生物技术学院,杭州310058

出　　处：《中国水稻科学》2018年第6期591-600,共10页Chinese Journal of Rice Science

基　　金：国家重点研发计划资助项目(2016YFD0300502);浙江大学大北农学科发展与人才培养基金;江苏省现代作物协同创新中心的资助

摘　　要：【目的】揭示水稻抽穗开花后剑叶衰老过程的内源自由态IAA和轭合态IAA含量的动态变化及其基因型间的差异,明确氮素营养供应对叶片衰老过程的延缓效应及其与两种化学态IAA含量之间的关系。【方法】以剑叶早衰水稻突变体(psf)与其野生型(浙恢7954)为材料,比较了其在大田条件下剑叶衰老过程中的内源IAA含量、IAA类型和YUCCAs家族基因转录表达量差异,并利用水培种植试验设低氮(LN,1.45mmol/L)、正常氮(NN,2.9mmol/L)和高氮(HN, 5.8 mmol/L)3个氮浓度水平处理,对不同氮素水平下水稻叶片衰老相关指标与两类IAA含量间的关系进行了分析。【结果】早衰突变体psf剑叶中的自由态IAA含量显著低于相同取样时期的野生对照,但前者剑叶中的轭合态IAA含量显著高于后者,且随叶片衰老进程呈较明显的上升趋势;在7个YUCCAs同工型基因中,YUCCA1、YUCCA2、YUCCA3、YUCCA4和YUCCA6)的转录表达量随叶片衰老而下降,但YUCCA7则随叶片衰老呈现出先上升后下降的变化趋势。相同灌浆时期相比,绝大多数YUCCAs在早衰突变体psf剑叶中的转录表达量要低于其野生型对照,说明IAA合成代谢较弱是psf剑叶叶绿素含量迅速下降和早衰症状加剧的重要原因之一。其中,YUCCA7转录表达量随叶片衰老而上升,可能对psf已衰老叶片中的IAA合成起重要调控作用;氮浓度对水稻叶片中的IAA含量及其自由态与共轭态的影响表现为,在叶片开始衰老的初期和前中期,低氮处理(LN)引起剑叶中的自由态IAA含量下降和轭合态IAA含量上升,而高氮处理(HN)可诱导叶片中的自由态IAA含量增加,并导致轭合态IAA含量明显降低,但对已严重衰老的叶片而言(psf在抽穗开花后28d的剑叶),高氮处理下(HN)的自由态IAA和轭合态IAA含量均低于正常氮处理(NN)和低氮处理(LN)。【结论】水稻叶片的衰老进程与其叶片器官中的IAA含量及其化学态之间存在较密切【Objective】The objective is to clarify the genotype-dependent alteration in rice leaf senescence process and its relationship with the endogenous IAA content and its conjugated status in flag leaves during filling stage,and also to investigate the effect of N supply levels on leaf senescence and its relation to the endogenous IAA content and its conjugated status in leaves for different rice genotypes.【Method】Two rice genotypes,namely,the premature senescence mutant in flag leaf(psf)and its wild type(Zhehui 7954),were used to compare their difference in the temporal patterns of IAA content and its conjugated status as well as transcriptional expression of YUCCAs family genes in flag leaf during filling stage.Three N levels,including low nitrogen level(LN,1.45 mmol/L),normal nitrogen level(MN,2.9 mmol/L),and high nitrogen level(HN,5.8 mmol/L),were designed to examine the response of IAA content and its conjugated status in senescent leaves to different N supply levels.【Result】The free IAA content in the flag leaf of psf mutant was significantly lower than that of its wild type during leaf senescence,while the opposite was true for the genotype-dependent alteration in the conjugated status IAA(IAA-ASP)content in senescent leaves,with a markedly higher level and more rapidly increase of IAA-ASP content in the flag leaf of psf mutant relative to its wild type along with leaf senescence.Among 7 YUCCAs isoform genes related to IAA biosynthesis,the transcriptional expressions of YUCCA2,YUCCA3,YUCCA4 and YUCCA6 were relatively lower in the flag leaf of psf mutant compared with its wild type,with the down-regulated temporal pattern during leaf senescence,regardless of rice genotypes.However,the transcript amount of YUCCA7 in senescent leaves increased markedly from 0 to 21 days post anthesis,followed by a declining level of transcriptional expression at the late stage of leaf senescence process.This result implied that the rapid decrease in chlorophyll contents and also its accelerated leaf senescence symptoms

关 键 词：水稻 叶片衰老 生长素 氮素营养 早衰突变体 

分 类 号：Q945.6[生物学—植物学] S143.1[农业科学—肥料学]