Insights into the Genomic Regions and Candidate Genes of Senescence-Related Traits in Upland Cotton via GWAS

Abstract

Senescence is the last stage of plant development and is controlled by both internal and external factors. Premature senescence significantly affects the yield and quality of cotton. However, the genetic architecture underlying cotton senescence remains unclear. In this study, genome-wide association studies (GWAS) were performed based on 3,015,002 high-quality SNP markers from the resequencing data of 355 upland cotton accessions to detect genomic regions for cotton senescence. A total of 977 candidate genes within 55 senescence-related genomic regions (SGRs), SGR1–SGR55, were predicted. Gene ontology (GO) analysis of candidate genes revealed that a set of biological processes was enriched, such as salt stress, ethylene processes, and leaf senescence. Furthermore, in the leaf senescence GO term, one candidate gene was focused on: Gohir.A12G270900 (GhMKK9), located in SGR36, which encodes a protein of the MAP kinase kinase family. Quantitative real-time PCR (qRT-PCR) analysis showed that GhMKK9 was up-regulated in old cotton leaves. Overexpression of GhMKK9 in Arabidopsis accelerated natural leaf senescence. Virus-induced gene silencing (VIGS) of GhMKK9 in cotton increased drought tolerance. These results suggest that GhMKK9 is a positive regulator and might be involved in drought-induced senescence in cotton. The results provide new insights into the genetic basis of cotton senescence and will be useful for improving cotton breeding in the future.

Research on Plant Genomics and Breeding 2.0

“…Liu et al identified a homologous gene, GhMKK9 , of the Arabidopsis cluster senescence gene AtMKK9 through GWAS analysis of 355 upland cotton materials. They found that GhMKK9 positively regulates plant senescence, with gene silencing delaying senescence in cotton and overexpression promoting senescence in Arabidopsis [ 3 ]. The sugar content in fresh maize stalks determines their value as green storage feed.…”

Research on Plant Genomics and Breeding

“…Liu et al analyzed the genetic basis of senescence in cotton using 355 upland cotton accessions planted in multiple environments for GWAS. From the candidate genes that have been linked, GhMKK9 silencing improves the drought resistance of cotton, whereas GhMKK9 overexpression accelerates senescence in Arabidopsis [21]. Areca catechu is a commercially important medicinal plant widely cultivated in tropical regions.…”

Hydrangea arborescens ‘Annabelle’ Flower Formation and Flowering in the Current Year

“…The interplay between different phytohormones in flower senescence have been extensively reviewed. ETH, ABA, and SA are recognized as key hormones that play an essential role in flower senescence [ 22 , 26 ]. Both ABA and IAA can accelerate the biosynthesis of ETH, leading to senescence.…”