Genetic analysis of environmental control of inflorescence development in perennial Arabis alpina

多年生高山南芥花序发育环境控制的遗传分析

• 批准号: 460364760
• 负责人: Dr. Niharika Sashidhar, Ph.D.
• 金额: --
• 依托单位: Abteilung Entwicklungsbiologie der Pflanzen
• 依托单位国家: 德国
• 项目类别: WBP Position
• 财政年份: 2021
• 资助国家: 德国
• 起止时间: 2020-12-31 至 2023-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/460364760?language=en
• 关键词: Genetic; analysis; environmental; control; inflorescence

Seasonal changes and daylength determine the appropriate timing of flowering in plants, to ensure the subsequent optimal production of seeds. In crucifers such as Arabis alpina and Brassica napus, the formation of flowers takes place in a two-step procedure, whereby buds are formed in one year and their outgrowth occurs in the following spring. However, the genetic mechanisms that underlie the seasonal regulation of bud arrest and inflorescence growth have not been examined in perennial plants. In this project, two different approaches will be used to analyse these mechanisms. First, a forward-genetic, QTL analysis will be applied to a Norwegian population of Arabis alpina that shows natural variation for flowering time and contains early- and late-flowering individuals. In early-, and late-flowering plants, floral buds are formed without vernalization at an approximately similar time; however, the floral buds of late-flowering plants arrest and generate mature inflorescences much more slowly. Vernalization of both genotypes overcomes the floral bud-arrest phenotype of the late-flowering parent, and both types flower at approximately the same time soon after vernalization. This suggests that these two accessions differ genetically at a checkpoint that arrests floral bud opening of the late type and that this can be overcome by vernalization. The host group has identified a QTL that contributes to the floral bud-arrest phenotype. The QTL has been localised to a 700-kb genomic segment of chromosome 8 in near-isogenic lines in which the locus segregates and the region has been assembled from PacBio reads. The causal gene responsible for the environmentally determined bud-arrest phenotype will be identified by further rounds of recombination mapping and its function will be analysed by expression analysis and transgenesis. Second, the Arabidopsis thaliana FT gene promotes flowering in long days and is proposed to regulate inflorescence development and flower-bud opening in Arabidopsis lyrata. However, the contribution of florigen-encoding FT genes to floral induction of perennial Brassicaceae such as Arabis alpina has not been analysed, mainly because AaFT null alleles are not available. Therefore, a reverse-genetic approach using CRISPR-Cas9 will be employed to generate knockout mutants of four AaFT genes with which to study the individual and combined contributions of the genes to floral induction, floral development and inflorescence development in different photoperiods and following vernalization. The two proposed approaches will not only identify the casual gene responsible for the bud-arrest phenotype in late-flowering Arabis alpina and contribute to current models for how floral buds formed during vernalization in autumn only produce open flowers and inflorescences in spring, but will allow comparative analysis of the function of florigen genes in related annual and perennial species.

季节变化和日照长度决定了植物开花的适当时间，以确保随后种子的最佳生产。在十字花科植物如Arabis alpina和Brassica napus中，花的形成发生在两个步骤中，其中芽在一年内形成，并且它们的生长在第二年春天发生。然而，在多年生植物中，芽停滞和花序生长的季节性调节的遗传机制尚未得到研究。在本项目中，将使用两种不同的方法来分析这些机制。首先，正向遗传，QTL分析将被应用到挪威人口的Arabis alpina，显示自然变化的开花时间，并包含早期和晚期开花的个人。在早花和晚花植物中，花芽在大致相同的时间形成而不进行春化;然而，晚花植物的花芽停滞并产生成熟的花序要慢得多。这两种基因型的春化克服了晚开花亲本的花芽停滞表型，并且这两种类型在春化后不久在大约相同的时间开花。这表明，这两个加入不同的遗传在一个检查点，逮捕花芽开放的晚型，这可以克服春化。宿主组已经确定了一个QTL，有助于花芽停滞表型。QTL已定位于近等基因系中8号染色体的700 kb基因组片段，其中该基因座分离，并且该区域已从PacBio读数组装。将通过进一步的重组作图来鉴定负责环境决定的芽停滞表型的致病基因，并通过表达分析和转基因来分析其功能。第二，拟南芥FT基因在长日照条件下促进开花，并被认为调节了拟南芥的花序发育和花芽开放。然而，尚未分析编码成花素的FT基因对多年生菊科植物如高山南芥（Arabis alpina）成花诱导的贡献，主要是因为AaFT无效等位基因不可用。因此，将采用使用CRISPR-Cas9的反向遗传方法来产生四个AaFT基因的敲除突变体，用其研究基因在不同光周期和春化后对成花诱导、花发育和花序发育的单独和组合贡献。这两个建议的方法不仅将确定休闲基因负责晚花南芥的芽逮捕表型，并有助于目前的模式，如何在春季春化过程中形成的花蕾在秋季只产生开放的花朵和花序，但将允许比较分析成花素基因的功能在相关的一年生和多年生植物。