水稻穗长QTL qPL3的鉴定与遗传效应分析

Identification and Genetic Effect Analysis of Panicle Length QTL qPL3 of Rice

水稻穗长是决定穗型的关键因素之一,与产量形成及品质改良密切相关。发掘穗长控制基因对于我国水稻育种及生产具有十分重要意义。以籼稻品种9311为供体、粳稻品种日本晴为背景的染色体片段代换系群体为研究对象,筛选到1个穗长较受体亲本日本晴显著变短的代换系N40。为了定位N40中控制穗长的QTL,构建了5个仅携带1个导入片段的单片代换系,其中,代换系N40-1仅在第3号染色体上携带1个导入片段,且其穗长与日本晴穗长相比显著变短,其他4个株系的穗长与日本晴穗长无显著差异。结果表明,N40-1携带的导入片段上含有穗长QTL,暂命名为qPL3。遗传分析结果表明,来源于籼稻9311的qPL3等位基因相对于日本晴表现为完全显性。随后利用构建染色体单片段叠代系的方法将qPL3初步定位于分子标记STS3-18与RM571之间,物理距离约为909.5 kb。同时,构建了日本晴背景下携带9311 qPL3位点的近等基因系,明确了日本晴背景下导入9311 qPL3等位基因能极显著降低植株的穗长、结实率及分蘖数,但并不影响穗粒数和株高。

Panicle length is one of the key factors determining panicle shape and closely related to yield formation and quality improvement.The discovery of control gene for panicle length is of great practical significance for rice breeding and production.In the previous study,CSSLs population with indica variety 9311 as donor and japonica variety Nipponbare as recipient were constructed.In this study,a substitution line N40 whose panicle length was significantly lower than that of Nipponbare was found.In order to map this QTL controlling panicle length in N40,five substitution lines with only one introduced fragment were constructed,among which N40-1 only carried one introduced fragment on chromosome 3,and its panicle length was significantly lower than that of Nipponbare.On the contrary,panicle length of the other 4 lines was not significantly different from that of Nipponbare.Those results suggested that the introduced fragment carried by N40-1 contained a panicle length QTL,which was tentatively designated as qPL3.Genetic analysis showed that the qPL3 allele derived from 9311 was completely dominant relative to Nipponbare.Ultimately,qPL3 was preliminarily located in the physical interval of 909.5 kb flanked by the molecular marker STS3-18 and RM571 via constructing a single-fragment line of chromosome substitution lines.A near-isogenic line carrying qPL3 locus under Nipponbare background was constructed,clarifying that the allele of qPL3 derived from 9311 qPL3 could significantly reduce panicle length,seed setting rate,and tiller number of plants,but did not affect grain number per panicle and plant height.