基于Meta-QTL和RNA-seq的整合分析挖掘水稻抗稻瘟病候选基因

Identification of rice blast resistance candidate genes based on integrating Meta-QTL and RNA-seq analysis

稻瘟病菌严重威胁水稻生产,且稻瘟病菌变异快导致抗稻瘟病品种在短短数年后就失去抗性。因此,不断挖掘新的抗稻瘟病基因对培育具有广谱抗病品种至关重要。本研究对43篇文献的783个抗稻瘟病QTL进行元分析,在12条染色体上鉴定到50个Meta-QTL (至少有2个原始QTL映射),平均区间距离为0.87 Mb,共计包含4718个区间基因。随后将抗稻瘟病Meta-QTL和RNA-seq进行整合分析,结果鉴定出2193个既定位于抗稻瘟病Meta-QTL区间上,又响应稻瘟病胁迫的显著差异表达的共同基因,其中22个基因已经克隆且被报道与水稻抗稻瘟病等逆境防御过程相关。此外,从上述共同基因中筛选出99个抗性基因类似物(resistance gene analogue,RGA)和112个转录因子(transcription factor,TF),对这些基因构建基因共表达网络图,基于连接度前20筛选出网络图的hub基因,其中OsJAMyb、bsr-d1和OsWRKY76已被报道与水稻抗稻瘟病相关,而OsSPL9参与水稻抗条纹病毒调控通路中,剩余hub基因作为重要的潜在抗性基因,有待进一步功能验证,为培育广谱抗性的水稻品种奠定基础。

Magnaporthe oryzae seriously devastates rice production, and resistant cultivars can lose resistance within a few years due to the pathogenic variability of M. oryzae. Therefore, it is essential to explore continuously novel blast-resistance genes for breeding broad-spectrum resistance cultivars. In this study, firstly, 50 Meta-QTLs(including at least 2 original QTLs) were identified on 12 chromosomes by meta-analysis of blast-resistance 783 QTLs from 43 literatures. The average interval distance was 0.87 Mb in these Meta-QTLs, which contained a total of 4718 interval genes. Subsequently, based on integrated analysis of blast-resistance Meta-QTLs and RNA-seq, the result identified 2193 common genes which were not only located on blast-resistance Meta-QTLs, but also significantly differentially expressed in response to the M. oryzae.Among them, 22 cloned genes had been reported to be involved in defense responses to M. oryzae and other stresses. Furthermore, 99 resistance gene analogues(RGA) and 112 transcription factors(TF) were screened out from the above common genes, which were utilized to construct gene co-expression networks(GCEN). Based on the Top 20 of the connection degrees, hub genes were identified in the GCEN. Among them, OsJAMyb, bsr-d1, and OsWRKY76 had been reported to be against rice blast, and OsSPL9 was related to resistance to rice stripe virus. The left hub genes were considered as important potential resistance genes which need further functional verification to prepare for breeding broad-spectrum resistance rice cultivars.