小麦新种质“普冰3228”穗下节长度QTL定位与候选基因分析

QTL mapping and candidate gene analysis of uppermost⁃internode length for new wheat germplasm‘Pubing3228’

【目的】挖掘小麦新种质“普冰3228”穗下节的有效位点/基因,探讨其穗下节分子遗传机制。【方法】以“普冰3228”ד京4839”杂交产生的210个小麦重组自交系群体为材料,利用55K SNP芯片构建该群体高密度分子遗传连锁图谱,采用完备区间作图法(ICIM⁃ADD)对穗下节长度进行QTL定位分析,并基于QTL定位结果对穗下节长度候选基因进行预测分析。【结果】研究发现210个小麦重组自交系遗传群体穗下节长度存在丰富的遗传差异,分布于16.00~117.50 cm。共检测到6个与小麦穗下节相关的QTL,该QTL主要分布于2B、4B、4D、5B和6D染色体上,其LOD值介于2.55~7.88,解释变异率分布于3.43%~15.84%,且绝大多数QTL均来自母本“普冰3228”。定位于4B染色体上AX⁃109373490~AX⁃111540511区间的QUIL⁃4B.e1和定位于4D染色体上AX⁃110984743~AX⁃109230716区间的QUIL⁃4D.e1为穗下节长度主效QTL,可在2种环境下均被检测到的QUIL⁃4D为穗下节长度稳定QTL。进一步分析发现15个与穗下节长度相关的候选基因。该候选基因主要编码一些相关蛋白及功能酶,通过调节或影响植物代谢活动进而对小麦穗下节长度产生影响。例如TraesCS4D01G039200可能编码一种原纤维家族蛋白,直接影响小麦穗下节长度,TraesCS4D01G040300可能编码代谢产物转运蛋白,通过调节代谢产物在穗下节区域的分配影响穗下节的长度。【结论】研究共检测到与小麦穗下节长度相关QTL 6个,预测到与穗下节相关候选基因15个,研究结果有助于小麦穗下节遗传机制解析,并为穗下节遗传改良提供新种质。

【Objective】The present study aimed to identify the new loci/genes controlling uppermost⁃internode length and explore the molecu⁃lar genetic mechanism of the uppermost⁃internode length in‘Pubing3228’.【Method】The high density molecular linkage map was construc⁃ted for the RIL population derived from the cross between‘Pubing3228’and‘Jing4839’using 55K SNP chip.Inclusive Composite Interval Mapping method was used to carry out QTL mapping for uppermost⁃internode length.Based on the identified QTLs,the candidate genes were predicted for uppermost⁃internode length.【Result】The large variation was found for the uppermost⁃internode length in the RIL population and the uppermost⁃internode length of each line varied from 16.00 to 117.50 cm.Total of 6 QTLs were identified for uppermost⁃internode length and these QTLs were distributed on chromosome 2B,4B,4D,5B and 6D.LOD value of these QTLs varied from 2.55 to 7.88 and the phenotypic variation explaination(PVE)of that ranged from 3.43%to 15.84%.Furthermore,most QTLs were contributed by‘Pubing3228’.Two major QTLs were identified for uppermost⁃internode length.One was QUIL⁃4B.e1 and was mapped to the distance be⁃tween AX⁃109373490 and AX⁃111540511 on chromosome 4B.Another was QUIL⁃4D.e1 and was mapped to the distance between AX⁃110984743 and AX⁃109230716 on chromosome 4D.One reliable QTL,QUIL⁃4D,was detected under two environments.The candidate a⁃nalysis was performed for uppermost⁃internode length and 15 candidate genes were obtained.These candidate genes mainly encoded some re⁃lated proteins and functional enzymes,which could regulate or affect plant metabolic activities and thus affect the uppermost⁃internode length of wheat.For example,TraesCS4D01G039200 possibly encoded a fibrillar family protein that could directly affect the uppermost⁃internode length of wheat.TraesCS4D01G040300 possibly encoded a metabolite transporter protein,which may affect the length uppermost⁃internode of wheat by regulating the distribution of metabolites in the uppermost⁃internode region.【Conclusion】Total of 6 QTLs and 15 candidate genes were identified for uppermost⁃internode length.These results not only help to elucidate the genetic mechanism of uppermost⁃internode length but also provide new wheat germplasm and effective information for the improvement of uppermost⁃internode length in the future.