Identification of candidate genes associated with peanut pod length by combined analysis of QTL-seq and RNA-seq.

Pod length (PL) is one of the major traits determining pod size and yield of peanut. Discovering the quantitative trait loci (QTL) and identifying candidate genes associated with PL are essential for breeding high-yield peanut. In this study, quantitative trait loci sequencing (QTL-seq) was performed using the F2 population constructed by a short-pod variety Tifrunner (Tif) and a long-pod line Lps, and a 0.77 Mb genomic region on chromosome 07 was identified as the candidate region for PL. Then, the candidate region was narrowed to a 265.93 kb region by traditional QTL approach. RNA-seq analysis showed that there were four differentially expressed genes (DEGs) in the candidate region, among which Arahy.PF2L6F (AhCDC48) and Arahy.P4LK2T (AhTAA1) were speculated to be PL-related candidate genes. These results were informative for the elucidation of the underlying regulatory mechanism in peanut pod length and would facilitate further identification of valuable target genes.

Integrative multi-omics analysis reveals the crucial biological pathways involved in the adaptive response to NaCl stress in peanut seedlings.

Plant growth is restricted by salt stress, which is a significant abiotic factor, particularly during the seedling stage. The aim of this study was to investigate the mechanisms underlying peanut adaptation to salt stress by transcriptomic and metabolomic analysis during the seedling stage. In this study, phenotypic variations of FH23 and NH5, two peanut varieties with contrasting tolerance to salt, changed obviously, with the strongest differences observed at 24 h. FH23 leaves wilted and the membrane system was seriously damaged. A total of 1470 metabolites were identified, with flavonoids being the most common (21.22%). Multi-omics analyses demonstrated that flavonoid biosynthesis (ko00941), isoflavones biosynthesis (ko00943), and plant hormone signal transduction (ko04075) were key metabolic pathways. The comparison of metabolites in isoflavone biosynthesis pathways of peanut varieties with different salt tolerant levels demonstrated that the accumulation of naringenin and formononetin may be the key metabolite leading to their different tolerance. Using our transcriptomic data, we identified three possible reasons for the difference in salt tolerance between the two varieties: (1) differential expression of LOC112715558 (HIDH) and LOC112709716 (HCT), (2) differential expression of LOC112719763 (PYR/PYL) and LOC112764051 (ABF) in the abscisic acid (ABA) signal transduction pathway, then (3) differential expression of genes encoding JAZ proteins (LOC112696383 and LOC112790545). Key metabolites and candidate genes related to improving the salt tolerance in peanuts were screened to promote the study of the responses of peanuts to NaCl stress and guide their genetic improvement.