调控玉米阻止授粉后叶片衰老的QTL定位

QTL mapping for pollination-prevention on leaf senescence

源-库比的变化与叶片的衰老速度有密切关系,但是关于叶片衰老的调控机制仍不清楚。为了进一步明确源-库比变化对玉米叶片衰老性状影响的遗传位点,利用B73×Mo17重组自交系群体,于2015年、2016年在抽丝前套袋阻止授粉后观察叶片衰老状况,取2年表型一致的142株植株并结合对应的基因型数据进行QTL分析,在第8条染色体的bnlg2046和gta101d 2个标记之间定位到一个显著QTL位点。该QTL的LOD值为3.64,贡献率为12.47%。标记之间的遗传距离为5.00 cM,物理距离为3.53 Mb。为进一步确认该QTL的准确性,利用来自于相同群体表型有明显差异的2个极端池的转录组测序数据,通过分群SNP分析(BSR-seq)后发现控制该性状的位点在同一染色体区段,其物理距离为4.47 Mb,该染色体区段共有85个基因。预测其中7个基因可能与叶片授粉被阻断后的叶片衰老性状有关。分析B73与Mo17在该区段的85个基因在抽丝期、抽丝后1周与抽丝后2周的转录组数据,结果显示,在预测的候选基因中,编码类WRKY家族转录因子的GRMZM2G432583以及编码E2结合酶的GRMZM2G007276和GRMZM2G132759在这几个时期的2个亲本中转录水平差异较大,是目的基因的可能性较大。本研究为阐明参与调控阻止玉米授粉后叶片衰老的基因和研究该性状产生的分子机制奠定了基础。

Source/sink ratio has close relationship with leaf senescence rate.The QTLs associating with pollinationprevention on leaf senescence has never been found yet in maize.To learn more about genetic mechanism of pollination-prevention on leaf senescence,recombinant inbred line (RIL population) derived from B73 × Mo17 was used to map the QTLs responsible for the phenotype.142 plants which have consistent pollination-prevented leaf senescence rate in 2 years were chosen and combined with corresponding genotype data for mapping target QTLs.One QTL located on chromosome 8between bnlg2046 and gta101 d was identified,with LOD score of 3.64.The genetic and physical distance of this genome region is 5.00 c M and 3.53 Mb respectively.To confirm this result,the plants showing most significant phenotypes were selected for bulk analysis.The sequence data were used to map the regions via bulked segregant RNA-Seq (BSR-Seq),and the same region on chromosome 8 was detected.The physical distance of this region was 4.47 Mb.There are 85 genes harbored in this zone,7 of which may be associated with leaf senescence rate after pollination-prevention.The B73 and Mo17 transcriptome data at silking,1 week after silking,and 2 weeks after silking was analyzed.Three of the predicted genes,GRMZM2G432583,encoding WRKY like transcription factor,and GRMZM2G007276 and GRMZM2G132759,both encoding conjugating enzyme E2s,showed significantly different transcription patterns in B73 and Mo17,indicative of the possibility of being target genes.This study paved the way for detecting genes and responding mechanisms involved in regulating pollination-prevention on leaf senescence.