Molecular basis of high temperature-induced bolting in lettuce revealed by multi-omics analysis.

BACKGROUND: High temperature induces early bolting in lettuce (Lactuca sativa L.), which affects both quality and production. However, the molecular mechanism underlying high temperature-induced bolting is still limited. RESULTS: We performed systematical analysis of morphology, transcriptome, miRNAs and methylome in lettuce under high temperature treatment. Through a comparison of RNA-Seq data between the control and the high temperature treated lettuces at different time points totally identified 2944 up-regulated genes and 2203 down-regulated genes, which cover three floral pathways including photoperiod, age and gibberellin (GA) pathways. Genome wide analysis of miRNAs and methylome during high temperature treatment indicated miRNAs and DNA methylation might play a role controlling gene expression during high temperature-induced bolting. miRNA targets included some protein kinase family proteins, which potentially play crucial roles in this process. CONCLUSIONS: Together, our results propose a possible regulation network involved in high temperature-induced bolting.

Genome-wide characterization and expression analysis of the auxin response factor (ARF) gene family during melon (Cucumis melo L.) fruit development.

ARFs in plants mediate auxin signaling transduction and regulate growth process. To determine genome-wide characterization of ARFs family in melon (Cucumis melo L.), ARFs were identified via analysis of information within the melon genomic database, and bioinformatic analyses were performed using various types of software. Based on different treatment methods involving dipping with the growth regulator Fengchanji No. 2 and artificial pollination, Jingmi No. 11 melon was used as the test material, and melon plants with unpollinated ovaries served as controls. The expression of ARFs during the early development of melon was analyzed via qRT-PCR. Seventeen genes that encode ARF proteins were identified in the melon genome for the first time. The expression of these ARFs differed in different tissues. The expression levels of CmARF2, CmARF16-like, CmARF18-like2, and CmARF19-like were especially high in melon fruits. The expression of ARFs during the early development of melon fruits differed in response to the different treatments, which suggested that CmARF9, CmARF16-like, CmARF19-like, CmARF19, CmARF1, CmARF2, CmARF3, and CmARF5 may be associated with melon fruit growth during early development. Interestingly, the increase in the transverse diameter of fruits treated with growth regulators was significantly greater than that of fruits resulting from artificial pollination, while the increase in the longitudinal diameter of the fruits resulting from artificial pollination was significantly greater.