In silico curation of QTL-rich clusters and candidate gene identification for plant height of bread wheat

Many genetic loci for wheat plant height(PH) have been reported, and 26 dwarfing genes have been catalogued. To identify major and stable genetic loci for PH, here we thoroughly summarized these functionally or genetic verified dwarfing loci from QTL linkage analysis and genome-wide association study published from 2003 to 2022. A total of 332 QTL, 270 GWAS loci and 83 genes for PH were integrated onto chromosomes according to their locations in the IWGSC RefSeq v2.1 and 65 QTL-rich clusters(QRC) were defined. Candidate genes in each QRC were predicted based on IWGSC Annotation v2.1 and the information on functional validation of homologous genes in other species. A total of 38 candidate genes were predicted for 65 QRC including three GA2ox genes in QRC-4B-IV, QRC-5A-VIII and QRC-6A-II(Rht24) as well as GA 20-oxidase 2(TaSD1-3A) in QRC-3A-IV. These outcomes lay concrete foundations for mapbased cloning of wheat dwarfing genes and application in breeding.

‘中山杉302’×墨西哥落羽杉回交子代叶片光合性状和叶绿素含量的QTL定位

对‘中山杉302’(Taxodium‘Zhongshanshan 302’)×墨西哥落羽杉(T.mucronatum Tenore)回交子代叶片的光合性状(包括净光合速率、气孔导度、胞间CO_(2)浓度和蒸腾速率)及叶绿素含量(包括叶绿素a、叶绿素b和总叶绿素含量)进行统计分析,并对这些性状进行QTL定位。结果表明:这7个性状的频率呈正态分布。净光合速率均值为3.91μmol·m^(-2)·s^(-1),气孔导度均值为0.23 mmol·m^(-2)·s^(-1),胞间CO_(2)浓度均值为190.94μmol·mol-1,蒸腾速率均值为5.17 mml·m^(-2)·s^(-1),叶绿素a、叶绿素b和总叶绿素含量均值分别为0.48、0.16和0.64 mg·g^(-1);胞间CO_(2)浓度变异系数最小(7.39%),其余6个性状变异系数较大,均在25.00%及以上,以气孔导度变异系数最大(43.48%)。QTL定位结果表明:除蒸腾速率和叶绿素b含量外,其余5个性状共定位到8个主效QTLs,包含98个SLAF标记,且这些主效QTLs的置信区间不同。净光合速率、气孔导度和叶绿素a含量各定位到1个主效QTL,分别位于1号连锁群(q 1-1)和11号连锁群(q 11-1和q 11-2),各包含25、3和13个SLAF标记,解释表型贡献率分别为5.68%、7.85%和10.95%;胞间CO_(2)浓度定位到2个主效QTLs,均位于6号连锁群(q 6-1和q 6-2),各含3和1个SLAF标记,解释表型贡献率分别为9.76%~10.70%和0.62%;总叶绿素含量定位到3个主效QTLs,分别位于1号连锁群(q 1-2)和11号连锁群(q 11-3和q 11-4),各包含26、26和1个SLAF标记,解释表型变异率为6.51%~6.64%、9.66%和6.60%。并且,q 6-2的加性效应值为正值,其余QTLs的加性效应值均为负值。研究结果显示:这8个主效QTLs的置信区间不同,不存在“一因多效”现象,且这些QTL区间基因主要参与光合性状和叶绿素含量的负调控。