胡杨幼苗生长的QTL功能定位

Functional Mapping of Seedling Growth for Populus euphratica Oliv.

幼苗建成是植物生活史中的重要组成阶段,幼苗生长为植物后续发育、抗性、产量提升等提供帮助。一般幼苗生长的研究多数集中于基因功能解析及各基因引起的表型变异,缺乏全基因组水平的系统性机制解析。为揭示幼苗生长的遗传机制,本研究以胡杨为试验材料,从中国西北胡杨自然分布区采集亲本,杂交获得F1子代群体,并对群体进行全基因组水平的分子标记测定。通过F1代群体在透明培养基的种子萌发实验,获得共计408个基因型单株的幼苗生长性状,包括不同时间点的茎高与根长表型。对不同时间点的生长数据构建动态表型向量,利用功能定位模型对茎高与根长进行QTL定位分析。模型利用生长曲线整合至统计框架的优势,对茎高定位出94个SNP位点,各分布于连锁群1、6、7、9、10、13、15、16、17、18、19;对主根长定位出130个显著SNP位点,其中31个位于蛋白编码基因区域。功能注释揭示了ABA信号与生长素响应通路的相关基因分别参与调控幼苗茎高与主根生长,泛素-26S介导的蛋白降解途径可同时参与茎高与主根长性状的遗传调控。功能定位为幼苗生长遗传结构的描绘提供了丰富结果,也将对重要沙漠树种的生长、胁迫防御等问题的研究起促进作用。

Seedling establishment is a key developmental stage in plant life cycle.Seedling growth lay an important foundation for improvement of growth and development during later stage,agroforestry field performance and plant resistance.However,traditional approaches had mostly focused on its phenotypic observation and molecular dissection of individual gene,lacking exploration of its underlying genetic mechanism at system level.To better shed light on the genetic mechanism of seedling growth,we utilized an F1 family of 408 intraspecific hybrids derived from two Populus euphratica trees that sampled from arid region of Northwest China,leading to detection of genome-wide SNP markers of all individual.By germination of individual seed using separate tube with transparent cultural medium,main stem height and taproot length were measured repeatedly over time.By using dynamic data of phenotype and genotype,functional mapping,a model integrating growth curves into a statistical framework was used to map QTLs affecting seedling growth.Model identified 94 significant SNPs affecting main stem height,locating on linkage group 1,6,7,9,10,13,15,16,17,18 and 19;130 SNPs were found regulating taproot length,31 out of the 130 significant markers were found to code known function protein.For stem height and taproot length,further annotation showed genes involved in abscisic acid(ABA)signaling and auxin response separately.What’s important is the co-existing ubiquitin-26 S mediated proteolysis pathway in both traits.Knowledge summarized with the functional mapping model provided rich results for charting an overall picture of the genetic architecture underlying seedling growth,and will facilitate studies into the mechanism mediating growth and stress defense for this important dessert tree species.