不同苜蓿品种秋眠级评定及其对越冬率的影响机理

发布时间：2018-05-19 03:43

本文选题：苜蓿 + 秋眠性　；参考：《中国农业科学院》2016年博士论文

【摘要】：秋眠性是紫花苜蓿(Medicago sativa L.)(以下简称“苜蓿”)对晚秋生长环境变化的一种适应性反应,是实现越冬、返青等过程的关键基础,秋眠性已被作为草地栽培与种植区划的主要依据之一。本研究以国外引进和国内审定登记的苜蓿品种为试验材料,以11个国际标准秋眠级苜蓿品种为对照材料,按照Teuber等方法对所有供试材料进行秋眠级和抗寒指数的评价,进而阐述秋眠级对建植次年苜蓿生产性能、越冬阶段根系性状及相关基因表达的影响,利用二代测序平台对不同秋眠型苜蓿根系进行转录组测序分析,筛选不同秋眠级苜蓿的差异表达基因,并研究差异基因的表达模式及可能参与的代谢通路,旨在为揭示苜蓿秋眠性的分子机理提供理论依据。主要结论如下:1.我国审定的苜蓿品种基本上属于秋眠型,秋眠性较强,其中公农2号、公农3号、海拉尔苜蓿及龙牧系列苜蓿品种的秋眠级为1级,甘农1号的秋眠级为2级。秋眠级对苜蓿建植次年第一茬产量等生产性能无显著影响,尽管夏季生长阶段株高与秋眠级之间没有关系,但不同秋眠级苜蓿的茎秆伸长策略显著不同,节间长和节间数与秋眠级或秋眠类型显著相关,高秋眠级(弱秋眠性)苜蓿的节间长较长,但节间数却随着秋眠级的增加呈递减趋势。2.通过对46个苜蓿品种(材料)秋眠级与抗寒指数、越冬率的关系进行分析发现,苜蓿秋眠级与抗寒指数呈极显著的正相关关系,与越冬率呈极显著的负相关关系,即秋眠性越强,苜蓿的越冬能力越强。不同秋眠级苜蓿的根系性状表现出对越冬低温胁迫的差异化响应特征,苜蓿主要通过增加根颈直径和侧根数来提高其抗寒性,并不取决于根系其他表型性状的绝对大小。3.在低温驯化阶段,随着秋眠级的增加,标准秋眠级苜蓿叶绿素含量、净光合速率呈现先增加后降低的趋势,叶片可溶性糖含量呈现下降的趋势。越冬期标准品种苜蓿根颈、主根、侧根氨基酸含量随秋眠级表现一致的变化规律,随着苜蓿秋眠性增强,各种氨基酸呈现显著的增加态势。随着秋眠性的增强,越冬期标准品种苜蓿根颈、主根、侧根抗寒基因cas18、vsp、corF的表达量呈现显著的增加趋势。4.应用Illumina NextSeq 500测序平台,对秋眠1级和9级的苜蓿根系样品进行转录组测序,共获得23,470个Unigene。其中16,190个Unigene被注释到一个或多个GO条目中,7,696个Unigene被成功注释到KEGG蛋白数据库的5条KEGG生化途径和321个代谢通路中,18,617个Unigene被注释到eggNOG蛋白数据库的25个功能类别中。经差异表达分析,共检测到2,326个差异表达基因,其中包括1,308个上调表达基因和1,018个下调表达基因。1,721个差异表达基因获得了GO功能注释。差异表达基因显著富集在能量代谢过程、次级代谢物的生物合成过程、碳水化合物代谢过程及氨基酸代谢过程等。此外,从苜蓿根系转录组中鉴定出1,497个转录因子和7,005个SSR。
[Abstract]:Autumn dormancy is Medicago sativa L. (hereinafter referred to as "alfalfa") an adaptive response to the late autumn growth environment is the key basis for the process of overwintering and returning to green. Autumn dormancy has been regarded as one of the main bases of grassland cultivation and planting regionalization. In this study, 11 international standard alfalfa varieties were used as experimental materials and 11 international standard alfalfa varieties were used as control materials. All the tested alfalfa varieties were evaluated for fall dormancy grade and cold resistance index according to Teuber and other methods. Furthermore, the effects of autumn dormancy on alfalfa production performance, root traits and related gene expression in winter stage were discussed, and transcriptional sequence analysis of different autumn dormant alfalfa roots was carried out by using the second generation sequencing platform. The differentially expressed genes of alfalfa with different fall dormancy levels were screened, and the expression patterns of differential genes and the metabolic pathways involved were studied in order to provide theoretical basis for revealing the molecular mechanism of autumn dormancy of alfalfa. The main conclusions are as follows: 1. The alfalfa varieties approved in our country basically belong to autumn dormancy type and have strong autumn dormancy. Among them, Gongnong 2, Gong Nong 3, Hailaer alfalfa and Longmu series alfalfa varieties have autumn dormancy grade 1 and Gannong 1 fall dormancy grade 2. Autumn dormancy had no significant effect on the first crop yield of alfalfa in the following year. Although there was no relationship between plant height and autumn dormancy in summer, the culm elongation strategies of alfalfa of different autumn dormancy levels were significantly different. Internode length and internode number were significantly correlated with autumn dormancy or fall dormancy type. The internode length of alfalfa with high autumn dormancy (weak autumn dormancy) was longer, but the internode number decreased with the increase of autumn dormancy. Based on the analysis of the relationship between fall dormancy grade and winter resistance index and winter resistance rate of 46 alfalfa varieties (materials), it was found that there was a very significant positive correlation between autumn hibernation level and winter resistance index, and a very significant negative correlation between fall hibernation level and wintering rate of alfalfa. That is, the stronger the autumn sleep, the stronger the winter ability of alfalfa. The root characters of different autumn dormancy alfalfa showed differential response to overwintering low temperature stress. Alfalfa improved its cold resistance mainly by increasing the diameter of root neck and the number of lateral roots, and did not depend on the absolute size of other phenotypic characters of root. In the low temperature acclimation stage, the chlorophyll content and net photosynthetic rate of standard autumn dormancy alfalfa increased first and then decreased, and the soluble sugar content of leaf decreased with the increase of autumn dormancy level. The content of amino acids in root neck, main root and lateral root of alfalfa during wintering period showed the same change rule with autumn dormancy grade. With the increase of autumn dormancy of alfalfa, all kinds of amino acids showed a significant increase trend. With the increase of autumn dormancy, the expression of root neck, main root and lateral root resistance gene cas18vspspcorF of standard varieties of alfalfa in overwintering stage showed a significant increasing trend .4. Using Illumina NextSeq 500 sequencing platform, 23470 Unigenes were obtained from alfalfa root samples of autumn sleep level 1 and 9 by transcriptome sequencing. 16190 Unigene were annotated into one or more go items, 7696 Unigene were successfully annotated into 5 KEGG biochemical pathways and 321 metabolic pathways in KEGG protein database, and 1 617 Unigene were annotated into 25 functional categories of eggNOG protein database. A total of 2326 differentially expressed genes were detected by differential expression analysis, including 1308 up-regulated genes and 1018 down-regulated genes. Differentially expressed genes were significantly enriched in energy metabolism, biosynthesis of secondary metabolites, carbohydrate metabolism and amino acid metabolism. In addition, 1497 transcription factors and 7005 SSRs were identified from alfalfa root transcriptome.
【学位授予单位】：中国农业科学院
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S541.9

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