【作者】 岳彩凤；

【导师】 郭天财； 康国章；

【作者基本信息】 河南农业大学 ， 作物栽培学与耕作学， 2008， 硕士

【摘要】 本试验以目前黄淮冬麦区大面积推广的弱春性小麦品种偃展4110、豫农949、郑麦9023和豫麦34为供试材料,采用分期播种试验的方法,系统观察了不同品种在不同播期条件下的幼穗发育进程,研究了低温胁迫条件下弱春性小麦品种间植株叶片与抗寒性密切有关的部分生理特性及保护酶基因的表达差异,分析了弱春小麦小麦品种对寒胁迫的生理响应。其主要研究结果如下:1.小麦的幼穗发育进程与其抗寒性密切相关。同为弱春性品种,其幼穗发育进程越快,遭受寒流侵袭后的冻害越重,如同为第一播期(10月5日)播种的4个弱春性小麦品种,寒流来临前主茎幼穗发育最快的豫麦34和郑麦9023两品种已分别达到小花分化末期和初期,寒流过后主茎幼穗冻死率分别为96%和73%;寒流来临前主茎幼穗发育到二棱后期的偃展4110幼穗冻死率为25%左右;而主茎幼穗发育最慢(二棱初期)的豫农949,仅有部分叶片的叶尖受冻。同时本研究还发现,在不同播期条件下幼穗发育进程相同的品种其受冻害程度却有一定差异,如第一播期的偃展4110和第二播期的豫麦34,寒流发生时其幼穗发育进程均为小花分化初期,前者有25%主茎幼穗冻死,而后者仅部分叶片的叶尖受冻枯死,进一步表明小麦品种的抗冻性与品种本身的遗传特性密切相关。2.在寒流发生期间和寒流来临前后,通过测定各供试品种植株叶片内部分与植物抗寒性密切相关的生理指标发现,寒流发生期间植株幼穗发育进程快且受冻害较重的豫麦34,其植株叶片中可溶性糖、可溶性蛋白和抗坏血酸(AsA)的含量均低于幼穗发育进程慢且受冻害较轻的品种豫农949和偃展4110,因此它们可以作为小麦抗寒性的鉴定指标;在寒流发生期间,4个弱春性小麦品种不同播期处理植株叶片内的脯氨酸(Pro)和谷胱甘肽(GSH)含量均比寒流来临之前有较大幅度的增加。同时发现幼穗发育进程快且受冻害较重的豫麦34和郑麦9023植株主茎叶片内上述两种物质的含量却高于幼穗发育进程慢且受冻害较轻的豫农949和偃展4110。因此,这两种物质只能作为评价品种抗冻性的参考指标,而不适合作为小麦抗冻性的鉴定指标。3.本试验从小麦叶片中克隆了谷胱甘肽还原酶(GR)、抗坏血酸过氧化酶(APX)、超氧物歧化酶(SOD)和过氧化氢酶(CAT)等保护酶基因的cDNA片段,通过半定量RT-PCR技术,研究了寒流发生期间和来临前后这些基因在小麦植株叶片中的表达特性,结果发现,寒流发生期间,幼穗发育进程慢且受冻害较轻的品种豫农949和偃展4110中的APX和SOD基因的表达量较高,且增幅较大,因此它们可以作为评价小麦抗寒性的鉴定指标;在寒流发生期间4个弱春性小麦品种的GR基因的表达量虽有所升高,但幼穗发育进程快且受冻害较重的豫麦34和郑麦9023第一播期处理的表达量却高于幼穗发育进程慢且受冻害较轻的豫农949和偃展4110,而CAT基因的表达量在寒流发生期间的变化不大,且处理间表达量没有规律。说明GR和CAT基因的表达量可能不适合作为小麦抗寒性的鉴定指标。综上所述,小麦的抗寒性与其幼穗发育进程密切相关,当寒流发生时,幼穗发育进程越慢的品种和各播期处理中其抗寒性表现越强;在寒流发生期间,幼穗发育进程较慢的品种叶片内可溶性糖、可溶性蛋白和AsA的含量较高,且APX和SOD两基因的表达量也较高,这些特性可以作为小麦抗寒性的鉴定指标;而Pro和GSH的含量和GR基因的表达量在此期间却低于幼穗发育进程较快且冻害较重的处理,CAT基因的表达量在寒流发生期间变化较小,且处理间没有规律,这些物质的含量及基因的表达量可能不适合作为小麦的抗寒性鉴定指标。更多还原

【Abstract】 Physiological mechanism on the difference in the antifreezing tolerance among weak springness wheat cultivars with different sowing dates was investigated in this paper.The processes of young spike development,the contents of antifreezing materials(soluble sugar,soluble porteins,proline,ascorbic acid and glutathione),and the expression of four protective enzyme(glutathione reductase, ascorbate peroxidase,catalase,superoxide dismutase genes) were measured under natural chilling current stress conditions,the main results were as follow:1.The processes of wheat young spike development were closely related to antifreezing tolerance,and the quicker development process of spike,the more serious freezing damage the wheat plant suffered during chilling current.For example,in the first sowing dates(2005-10-05),the quicker development processes of young spike between Yumai 34 and Zhengrnai 9023 cultivars had reached to the late and initial stages of floret differentiation,respectively,and there appeared more serious freezing injury on the two cultivars during chilling current.The freezing mortality of young spikes of these cultivars at two processes were to 96%and 73%,respectively.The processes of wheat young spike development of Yanzhan 4110 cultivar reached to the late stage of two prisms before this chilling current,and the freezing mortality of young spikes was to 25%.The slower development processes of young spike in Yunong 949 cultivar had only reached to the initial stage of two prisms,and there appeared slight freezing injury at the tip of leaves.In addition,there were differences in freezing injuries of young spikes with the same developmentl processes.For example,the development processes of wheat young spikes betweenYanzhan 4110 in the first sowing dates and Yumai 34 in the second sowing dates reached to the same stage(initial stage of floret differentiation), but the freezing mortality rates of spikes in the former were 25%,but there apperaed only slight freezing injury at the tip of leaves in the latter cultivar.The results showed that genetic traits may be also related to freezing resistance of wheat cultivars.2.Before,during and afer chilling current in 2005 winter season.,the contents of soluble sugar,soluble portein,AsA in Yumai 34 plants with the quicker development processes of young spikes and more serious freezing injury were lower than those of Yunong 949 and Yanzhan 4110 with the slower development process of spikes.These result showed that they could be used as indexes to detect the freezing resistance of wheat plants.During chilling current,the contents of Pro and GSH in the leaves of four wheat cultivars with the different sowing dates sharply increased but the contents of them in the leaves of Yumai 34 plants with the quicker development processes of young spikes were higher than those of Yunong 949 and Yanzhan 4110 with the slower development process of spikes.The result implied that Pro and GSH could hardly reflect freezing tolerance of wheat cultivars.3.cDNA fragments of four protective enzyme genes(GR,APX,SOD,and CAT) were cloned from wheat leaves.Their expression in leaves of the above wheat plants before,during and after chilling current was investigated by semi-quantitative RT-PCR.The result showed that the transcript levels and the increasing amplitude of APX and SOD genes were higher in Yunong 949 and Yanzhan 4110 with slower development processes of spikes with slight freezing injury than those with quicker development processes,indicating that they could be used as the indexes to measure the freezing tolerance of wheat plants.The transcript levels of GR genes slightly increasd in all checked wheat plants,but its transcripts in Yumai 34 and Zhengmai 9023 cultivars with the quicker development process of spikes and more serious freezing injury were higher than those with the slower development process of spikes in Yunong 949 and Yanzhan 4110 cultivars.There appeared little changes and difference in transcript levels of CAT gene in all the checked plants.These results suggested that the changes in transcript levels of GR and CAT genes could not be suitable as the indexes of the freezing tolerance among wheat cultivars.In summary,the antifreezing tolerance of wheat plants was closely related to the development processes of young spikes.The slower development process of spikes, the stronger antifreezing tolerance of wheat plants there appeared during chilling current.The contents of soluble sugar,soluble porteins,AsA and the transcript levels of APX and SOD genes in plant leaves with the slower development process of spikes were higher than those with quicker development processes of spikes.These materials could be used as the indexes of the freezing tolerance of wheat.But the contents of Pro,GSH and the transcript levels of GR gene in plant leaves with the slower development process of spikes were lower than the latter,and there appeared little changes and differences in transcript levels of CAT gene in all the checked plants. These could not be suitable as the indexes of the freezing tolerance among wheat cultivars.更多还原