Overexpression of PvSTK1 gene from Switchgrass (Panicum virgatum L.) affects flowering time and development of floral organ in transgenic Arabidopsis thaliana.

Flowering means that the plant enters the reproductive growth stage, which is a crucial stage in the plant life cycle. Delaying flowering time to prolong vegetative growth is an important method to increase biomass yield and saccharification efficiency in switchgrass, It is of great significance to study the molecular mechanism of plant flowering and regulate the process of plant flowering in the process of biomass production. In this study, we identified 55 serine/threonine-protein kinase genes related to flower development from the switchgrass transcriptome database. Simultaneously, we cloned one of them, PvSTK1, whose expression level and differential fold were significantly higher than other members. PvSTK1 is located on chromosome 8N and its protein was in the cell membrane, cytoplasm, and nucleus. The spatio-temporal expression analysis of the PvSTK1 in switchgrass displayed that the PvSTK1 is crucial in vegetative period, however, not in the transition to reproductive period. Overexpression of PvSTK1 in Arabidopsis resulted in down-regulation of flower-promoting genes and up-regulation of flower-suppressing genes, thereby delaying flowering. In addition, PvSTK1 caused atrophy of the ovules of the florets at the base of the inflorescence, leading to sterility of the florets. The function of PvSTK1 is to inhibit the development of floral organs, and its overexpression can prolong its vegetative period. In the future, overexpression of the PvSTK1 gene in switchgrass will change the flowering time and increase yield and utilization efficiency of biomass.

Regulatory Network of Preharvest Sprouting Resistance Revealed by Integrative Analysis of mRNA, Noncoding RNA, and DNA Methylation in Wheat.

Preharvest sprouting (PHS) of grain occurs universally and sharply decreases grain quality and yield, but the mechanism remains unclear. MingXian169, a breeding inducer wheat for stripe rust, is widely used in the Huanghuai wheat-producing region, China. In this study, we found that MingXian169 could be considered an ideal material for PHS research because of its high PHS resistance. To further analyze the network of PHS, transcriptome sequencing of mRNA, noncoding RNA (ncRNA), and DNA methylome data were used to comparison germination seeds (GS) and dormant seeds (DS); 3027, 1516, and 22 genes and 95 103 methylation regions were identified as differentially expressed mRNA, DE-microRNAs (DE-miRNA), DE-long noncoding RNAs (DE-lncRNA), and differentially methylated regions (DMRs). Pathway enrichment tests highlighted plant hormone biosynthesis and signal transduction, glutathione-ascorbate metabolism, and starch and sucrose metabolism processes related to PHS mechanisms. Further analysis demonstrated that long noncoding RNA, miRNA, and DNA methylation played critical roles in transcriptional regulation of critical pathways during PHS by modifying and interacting with target genes. Quantitative real-time polymerase chain reaction (PCR) analyses of mRNA and miRNA confirmed the sequencing results. In the phytohormone content assay, abscisic acid (ABA) and jasmonic acid (JA) increased significantly in DS, and GA19 increased in GS. The ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), and ß-d-glucosidase (BGLU) enzyme activities and the substance content of glutathione and sucrose were significantly higher in GS than in DS, implying that they were responsible for increasing PHS in MingXian169. Our results provide new insights into wheat PHS resistance at mRNA, ncRNA, and DNA methylation levels, with suggestions for crop breeding and production.