【摘要】 【目的】通过对水稻籽粒大小相关性状进行QTL定位及候选基因的筛选,为水稻籽粒大小相关基因的精细定位、克隆及基因功能等研究奠定基础。【方法】以籼稻品种特华占搭载高空气球空间诱变后产生的特异矮秆突变体CHA-1为母本,以籼稻品种航恢7号搭载"神州八号"飞船经空间诱变后筛选出的突变体H335为父本杂交衍生出的275个RIL群体作为供试材料,利用GBS测序技术构建高密度遗传图谱,RIL群体及亲本分别于2017年早季和2017年晚季在华南农业大学实验教学基地种植。成熟收获后通过扫描仪获取水稻籽粒图像,利用SmartGrain软件获取籽粒大小相关性状表型数据。采用QTL IciMapping v 4.0软件基于完备复合区间作图法,对水稻籽粒大小相关性状进行QTL定位。【结果】构建的高密度遗传图谱包含2 498个Bin标记,总图距2 371.84cM,标记间平均遗传图距为0.95 cM。两季共检测到26个籽粒大小相关QTL,分布于第1、2、3、4、7和9染色体上,单一QTL贡献率为0.16%—14.41%。在第1、2、3、7染色体上检测到5个QTL簇(qGS1、qGS2、qGS3-1、qGS3-2和qGS7)。其中qGS1、qGS3-2和qGS7与前人报道相似,qGS2和qGS3-1是新发现的籽粒大小相关QTL,qGS2在2个季别的不同性状中被检测在同一标记区间附近,LOD值介于4.00—8.08,贡献率为6.67%—11.38%。qGS3-1在2个季别下均检测到与籽粒厚度相关,LOD值介于2.94—8.59,贡献率为4.69%—14.41%。使用的高密度遗传图谱定位区间较小,结合功能注释和CREP数据库表达谱,在qGS2位点筛选到4个潜在的与籽粒大小相关的注释基因LOC_Os02g42310、LOC_Os02g42314、LOC_Os02g42370和LOC_Os02g42380。其中LOC_Os02g42310编码一个丝氨酸羧肽酶;LOC_Os02g42314编码一个泛素E2结合酶;LOC_Os02g42370编码一个类受体蛋白激酶;LOC_Os02g42380编码一个TCP转录因子。在qGS3-1位点筛选到3个潜在的与籽粒大小相关的注释基因LOC_Os03g39020、LOC_Os03g39150和LOC_Os03g39230。其中LOC_Os03g39020编码一个驱动蛋白结构域;LOC_Os03g39150编码一个蛋白激酶结构域;LOC_Os03g39230编码一个具有去蛋白质泛素化功能的OTU-like半胱氨酸肽酶。其中编码泛素E2结合酶的LOC_Os02g42314和编码驱动蛋白结构域的LOC_Os03g39020在幼穗和授粉后的胚乳中表达量较高,推测其为最可能的调控籽粒大小的候选基因。【结论】共检测到26个水稻籽粒大小相关QTL。在第1、2、3和7染色体上检测到5个QTL簇(qGS1、qGS2、qGS3-1、qGS3-2和qGS7),其中qGS2和qGS3-1为新发现的控制籽粒大小QTL,并在该位点筛选到2个可能调控水稻籽粒大小相关的候选基因。更多还原

【Abstract】 【Objective】Combine QTL mapping for grain size and related traits and screening for candidate genes to lay a good foundation for dissecting genes regulating rice grain size and related traits.【Method】A dwarf mutant CHA-1 screened from the progeny of the indica rice variety Tehuazhan carried by high altitude balloon was hybridized with another mutant H335 selected from the progeny of the indica rice variety Hanghui 7 induced by "Shenzhou 8" spaceflight. A population of 275 recombinant inbred lines(RILs) was structured from CHA-1 × H335. A high-density genetic map was constructed using genotyping by sequencing(GBS) technology. The RIL population and parents were grown in the experimental base of South China Agricultural University consecutively in the early and late season in 2017. After ripening, rice grain images were scanned, and the grain size and related traits was obtained by SmartGrain software. QTL mapping for rice grain size and related traits was done with QTL IciMapping v 4.0 software based on inclusive composite interval mapping(ICIM).【Result】The constructed high-density genetic map contains 2498 Bin markers,and all the markers covers 2371.84 cM with an average genetic distance of 0.95 cM/marker. A total of 26 grain-size related QTLs were repeatedly detected on Chr.1, Chr.2, Chr.3, Chr.4, Chr.7 and Chr.9 in the two seasons with single QTL contribution rate ranged from 0.16% to 14.41%. Five QTL clusters(qGS1, qGS2, qGS3-1, qGS3-2, qGS7) were detected on Chr.1, Chr.2, Chr.3, and Chr.7. Among them, qGS1, q GS3-2, and qGS7 have been previously reported. qGS2 and qGS3-1 were novel grain-size related QTLs. qGS2 was repeatedly detected in the same marker interval in the two seasons, and its LOD values in the early and late season were 8.08 and 4.00 with the phenotypic contribution rate 11.38% and 6.67%, respectively. qGS3-1 was detected to be correlated with grain thickness in the two seasons, and its LOD values in the early and late season were 2.94 and 8.59 with the phenotypic contribution rates 4.69% and 14.41%, respectively. Combined with functional annotation and CREP database of gene expression profiles, four candidate grain-size related genes including LOC_Os02 g42310, LOC_Os02 g42314, LOC_Os02 g42370 and LOC_Os02 g42380 were screened out in the qGS2 locus. LOC_Os02 g42310 encodes a serine carboxypeptidase homologue; LOC_Os02 g42314 encodes a ubiquitin-conjugating enzyme; LOC_Os02 g42370 encodes a protein kinase domain containing protein; LOC_Os02 g42380 encodes a TCP domain containing protein. Three candidate grain-size related genes including LOC_Os03 g39020, LOC_Os03 g39150 and LOC_Os03 g39230 were screened out in the qGS3-1 locus. LOC_Os03 g39020 encodes a kinesin motor domain containing protein; LOC_Os03 g39150 encodes a protein kinase domain containing protein; LOC_Os03 g39230 encodes an OTU-like cysteine protease family protein. Among the genes, LOC_Os02 g42314 and LOC_Os03 g39020 were highly expressed in the young panicle and endosperm after pollination and recognized as the most possible candidate genes for regulating grain size.【Conclusion】 26 rice grain-size related QTLs were detected. Five QTL clusters(qGS1, qGS2, qGS3-1, qGS3-2, qGS7) were detected on Chr1, Chr.2, Chr.3, and Chr.7, and q GS2 and qGS3-1 were novel QTLs for regulating grain size, and two candidate genes were screened out in this locus.更多还原