苹果砧木茎源根系发生中次生代谢、内源激素和转录组差异分析

发布时间：2019-03-27 14:31

【摘要】：植物向重力性定点角(gravitropic setpoint angle,GSAs)是指由植物向重力性所决定的、植物器官在重力(gravity)作用下所保持的角度。植物器官的GSAs范围一般为0-180o,幼苗根的GSA为典型的0o,其茎的GSA为典型的180o。苹果生产应用自根砧木,树体一致性强,果实商品性高,是发达国家主要生产模式,但是自根砧根系浅、固地性差,在我国瘠薄果园土壤上表现欠佳,导致其在我国苹果生产中推广缓慢。因此,进行苹果自根砧不定根向重力性定点角(GSAs)影响因子的研究具有重要的理论和实践意义。本研究前期筛选了3种近缘根性不同苹果自根砧,表现出不同的不定根分支角度,并以此为试材,从植物激素、插穗次生代谢产物分析入手,利用转录组学技术研究插穗中不定根向重力性定点角形成的影响因素,旨在探讨插穗内的次生代谢产物在不定根GSAs发生中的作用。苹果自根砧不定根发生发育过程中,插穗中生长素(auxin)的含量呈先升高再降低的趋势,脱落酸(ABA)和异戊烯基腺嘌呤(iPA)含量总体呈下降趋势,玉米素核苷ZR含量变化趋势呈“W”型,而赤霉素GA_3含量则呈“V”型。在不定根GSAs形成时期,深层根型插穗中的内源IAA含量迅速降低,而内源玉米素核苷ZR和赤霉素GA_3的含量在深层根型、中间根型和浅层根型插穗中依次降低,IAA/ZR和IAA/GA_3则依次升高。苹果自根砧嫩枝扦插插穗的挥发性物质成分主要为酯类化合物(44.34%)和醇类化合物(41.27%);其中,E-4-己烯-1-醇[4-Hexen-1-ol,(E)-]的相对含量最高,为33.96%,其次是Z-乙酸-3-己烯-1-醇酯[3-Hexen-1-ol,acetate,(Z)-](20.18%)和甲酸己酯[Formic acid,hexyl ester](15.11%)。不定根GSAs不同的插穗中,挥发性物质的相对含量不同,尤其E-2-己烯醛[2-Hexenal,(E)-],随着不定根GSAs的增大,其相对含量逐渐增多。利用Illumina HiSeq 2500测序平台,分别对不定根发育过程的3个时期的转录组进行测序分析。测序共获得9个样本的原始reads,总数为36,919,140到38,793,530,每个样品约有24 millionreads与参考基因组比对成功,有效比对率为86.03%-88.87%。不定根GSAs形成时期,基因DFR、HCT1A和CYP78A5等下调,促进了柚皮素、槲皮素等类黄酮化合物和生物碱化合物的合成。
[Abstract]:Plant-to-gravity fixed point angle (gravitropic setpoint angle,GSAs) refers to the angle which is determined by plant gravity and maintained by plant organs under the action of gravity (gravity). The GSAs range of plant organs is generally 0. 180 o, the GSA of seedling roots is typical 0 o, and the GSA of stem is 180 o. The application of self-root rootstock in apple production has strong consistency and high commodity, which is the main production mode in developed countries. However, the root system of self-root rootstock is shallow and the soil is poor in barren orchards in China. It leads to its slow spread in apple production in China. Therefore, it is of great theoretical and practical significance to study the influence factors of the fixed-point angle (GSAs) on the adventitious root-fixed angle of apple stock. In the early stage of this study, three kinds of self-root rootstocks with different root characteristics were screened, showing different angles of adventitious root branches, and using them as test materials, starting with the analysis of plant hormones and secondary metabolites of cuttings. In order to explore the role of secondary metabolites in the formation of adventitious root GSAs in cuttings, the factors affecting the formation of adventitious root-gravity fixed-point angles in cuttings were studied by using transcriptometry technique in order to explore the role of secondary metabolites in adventitious root formation in cuttings. During the development of adventitious root of apple root stock, the content of auxin (auxin) in cuttings increased at first and then decreased, while the content of (ABA) and isoamyl adenine (iPA) decreased in general. The ZR content of zeatin showed "W" type, while gibberellin GA_3 content showed "V" type. During the formation of adventitious root GSAs, the content of endogenous IAA in deep root type cuttings decreased rapidly, while the contents of endogenous zeatin nucleoside ZR and gibberellin GA_3 decreased sequentially in deep root type, middle root type and shallow root type cuttings. IAA/ZR and IAA/GA_3 increased in turn. The volatile compounds in the cuttings of apple self-rootstock were mainly esters (44.34%) and alcohols (41.27%), and the main volatile compounds in the cuttings were esters (44.34%) and alcohols (41.27%). Among them, the relative content of 4-hexene-1-ol (E) -) was the highest (33.96%), followed by Z-acetic acid-3-hexene-1-ol (3-hexene-1-ol, acetate), (Z) -] (20.18%) and hexyl formate [Formic acid,hexyl ester] (15.11%). The relative contents of volatile substances in different cuttings of adventitious root GSAs were different, especially the relative content of Ex2-hexenal [2-hexenal, (E) -] increased gradually with the increase of GSAs in adventitious roots. The transcripts from three stages of adventitious root development were sequenced using Illumina HiSeq 2500 sequencing platform. The total number of original reads, from 9 samples was 36919140 to 38,793 and 530, and about 24 millionreads per sample was successfully compared with the reference genome, with an effective ratio of 86.03% to 88.87%. The down-regulation of genes DFR,HCT1A and CYP78A5 during the formation of adventitious root GSAs promoted the synthesis of flavonoids and alkaloids, such as naringin, quercetin and so on.
【学位授予单位】：山东农业大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S661.1

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