ABSTRACT
High seed vigor is crucial for agricultural production owing to its potential in high quality and yield of crops and a better understanding of the molecular mechanism associated with maize seed vigor is highly necessary. To better understand the involvement and regulatory mechanism of miRNAs correlated with maize seed vigor, small RNAs and degradome sequencing of two inbred lines Yu537A and Yu82 were performed. A total of 791 mature miRNAs were obtained with different expressions, among of which 505 miRNAs were newly identified and the rest miRNAs have been reported before by comparing the miRNAs with the sequences in miRbase database. Analysis of miRNA families showed maize seeds contain fewer miRNA families and larger miRNA families compared with animals, indicating that functions of miRNAs in maize seeds were more synergistic than animals. Degradome sequencing was used to identify the targets of miRNAs and the results showed a total of 6,196 targets were obtained. Function analysis of differentially expressed miRNAs and targets showed Glycan degradation and galactose metabolism were closely correlated with improved maize seed vigor. These findings provide valuable information to understand the involvement of miRNAs with maize seed vigor and these putative genes will be valuable resources for improving the seed vigor in future maize breeding.
ABSTRACT
Seed germination, as an integral stage of crop production, directly affects Zea mays (maize) yield and grain quality. However, the molecular mechanisms of seed germination remain unclear in maize. We performed comparative transcriptome analysis of two maize inbred lines, Yu82 and Yu537A, at two stages of seed germination. Expression profile analysis during seed germination revealed that a total of 3381 and 4560 differentially expressed genes (DEGs) were identified in Yu82 and Yu537A at the two stages. Transcription factors were detected from several families, such as the bZIP, ERF, WRKY, MYB and bHLH families, which indicated that these transcription factor families might be involved in driving seed germination in maize. Prominent DEGs were submitted for KEGG enrichment analysis, which included plant hormones, amino acid mechanism, nutrient reservoir, metabolic pathways and ribosome. Of these pathways, genes associated with plant hormones, especially gibberellins, abscisic acid and auxin may be important for early germination in Yu82. In addition, DEGs involved in amino acid mechanism showed significantly higher expression levels in Yu82 than in Yu537A, which indicated that energy supply from soluble sugars and amino acid metabolism may contribute to early germination in Yu82. This results provide novel insights into transcriptional changes and gene interactions in maize during seed germination.
