Comprehensive Evaluation and Transcriptome Analysis Reveal the Salt Tolerance Mechanism in Semi-Wild Cotton (Gossypium purpurascens)

Abstract

Elevated salinity significantly threatens cotton growth, particularly during the germination and seedling stages. The utilization of primitive species of Gossypium hirsutum, specifically Gossypium purpurascens, has the potential to facilitate the restoration of genetic diversity that has been depleted due to selective breeding in modern cultivars. This investigation evaluated 45 G. purpurascens varieties and a salt-tolerant cotton variety based on 34 morphological, physiological, and biochemical indicators and comprehensive salt tolerance index values. This study effectively identified a total of 19 salt-tolerant and two salt-resistant varieties. Furthermore, transcriptome sequencing of a salt-tolerant genotype (Nayanmian-2; NY2) and a salt-sensitive genotype (Sanshagaopao-2; GP2) revealed 2776, 6680, 4660, and 4174 differentially expressed genes (DEGs) under 0.5, 3, 12, and 24 h of salt stress. Gene ontology enrichment analysis indicated that the DEGs exhibited significant enrichment in biological processes like metabolic (GO:0008152) and cellular (GO:0009987) processes. MAPK signaling, plant-pathogen interaction, starch and sucrose metabolism, plant hormone signaling, photosynthesis, and fatty acid metabolism were identified as key KEGG pathways involved in salinity stress. Among the DEGs, including NAC, MYB, WRKY, ERF, bHLH, and bZIP, transcription factors, receptor-like kinases, and carbohydrate-active enzymes were crucial in salinity tolerance. Weighted gene co-expression network analysis (WGCNA) unveiled associations of salt-tolerant genotypes with flavonoid metabolism, carbon metabolism, and MAPK signaling pathways. Identifying nine hub genes (MYB4, MYB105, MYB36, bZIP19, bZIP43, FRS2 SMARCAL1, BBX21, F-box) across various intervals offered insights into the transcriptional regulation mechanism of salt tolerance in G. purpurascens. This study lays the groundwork for understanding the important pathways and gene networks in response to salt stress, thereby providing a foundation for enhancing salt tolerance in upland cotton.

Transcriptomic analysis reveals the beneficial effects of salt priming on enhancing defense responses in upland cotton under successive salt stress

“…The high number of unique DEGs in T compared to other genotypes indicates its reservoir of genetic diversity. Modern upland cotton varieties have faced genetic bottlenecks due to intensive selection, resulting in erosion of stress tolerance traits (Peng et al, 2023;Cheng et al, 2023). G. hirsutum purpurascens represents untapped adaptive potential that could be introgressed into elite cultivars to improve salinity tolerance.…”

Transcriptome dynamics of Gossypium purpurascens in response to abiotic stresses by Iso-seq and RNA-seq data

“…Plant materials and treatment. Salt and saline-alkali resistant genotype of G. purpurascens (K411: Zhanjiang Naozhou Liuluo-2) were used for Iso-seq and RNA seq 19,20 . Furthermore, it should be noted that this specific genotype has undergone prior investigation, and was determined to possess resistance to high levels of salt 20 .…”

Transcriptome Expression Profiling Reveals the Molecular Response to Salt Stress in Gossypium anomalum Seedlings

“…Due to its adaptation to harsh environments, plants of this species exhibit morphological phenotypes that increase tolerance to abiotic stress, such as small and deeply parted palmate leaves, thick and hard seed coats, and dense hairs. In addition, improvement of a plant’s resistance to stress is closely tied to the effectiveness of its antioxidant enzyme system [ 11 , 12 ]. Therefore, G. anomalum is a valuable wild species for increasing our understanding of the mechanism and biological functions of genes related to abiotic stress in Gossypium spp.…”