基于RNA-seq挖掘甜玉米苗期响应铝胁迫的激素信号关键基因OA

To elucidate the molecular mechanisms underlying aluminum(Al)stress response in sweet corn seedlings,a comparative transcriptome analysis was conducted using an Al-tolerant inbred line(T56)and an Al-sensitive inbred line(T49).Seedlings at the two-leaf-one-heart stage were subjected to Al stress,and root tips were sampled at 0-,1-,4-,and 24-hours post-treatment.RNA sequencing,combined with differentially expressed gene(DEG)analysis,GO/KEGG enrichment analysis,and qRT-PCR validation,was employed to identify key hormone-related genes involved in the early Al stress response.The results indicated that differences in hematoxylin staining of root tips became detectable after 4 h of Al stress.After 24 h of treatment,the stained region in T56 root tips was restricted to the apical meristem,while the staining in T49 had penetrated into the root vascular bundle.After 12 d of Al stress,both T56 and T49 showed significant reductions in seedling height,root length,fresh weight,and dry weight,but the decrease in T56 was smaller than that in T49,indicating its stronger Al tolerance.Transcriptome analysis revealed that the total number of DEGs increased progressively with prolonged stress duration,and the global response patterns markedly differed between the two inbred lines.GO enrichment analysis indicated that DEGs at early-stage(1 h)were significantly enriched in organic acid metabolism and redox processes.The mid-stage(4 h)transcriptional responses were primarily directed to the inositol biosynthesis pathway,while DEGs identified at the late-stage(24 h)were predominantly associated with lipid homeostasis and redox processes.KEGG analysis showed significant enrichment of sulfur metabolism at 4 h,and activation of plant hormone signal transduction,phenylpropanoid biosynthesis,and monoterpenoid biosynthesis pathways at 24 h.Further analysis revealed that T56 rapidly established a systematic defense network via coordinated regulation of auxin,zeatin,abscisic acid,and salicylic acid signaling,whereas the corresponding hormonal response in T49 was weaker and delayed.A total of 15 hormone-responsive DEGs were found to harbor non-synonymous nucleotide variants,which may serve as potential candidate genes.This study delineates the dynamics transcriptional reprogramming in sweet corn seedlings under Al stress,highlights the pivotal regulatory role of hormone signaling pathways,and provides a foundation for deciphering the molecular basis of Al tolerance in sweet corn.