Comparative Transcriptome Analysis Provides Insights into the Seed Germination in Cotton in Response to Chilling Stress

Abstract

Gossypium hirsutum L., is a widely cultivated cotton species around the world, but its production is seriously threatened by its susceptibility to chilling stress. Low temperature affects its germination, and the underlying molecular mechanisms are rarely known, particularly from a transcriptional perspective. In this study, transcriptomic profiles were analyzed and compared between two cotton varieties, the cold-tolerant variety KN27-3 and susceptible variety XLZ38. A total of 7535 differentially expressed genes (DEGs) were identified. Among them, the transcripts involved in energy metabolism were significantly enriched during germination based on analysis of Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, such as glycolysis/gluconeogenesis, tricarboxylic acid cycle (TCA cycle), and glyoxylate cycle (GAC). Results from further GO enrichment analysis show the earlier appearance of DNA integration, meristem growth, cotyledon morphogenesis, and other biological processes in KN27-3 compared with XLZ38 under chilling conditions. The synthesis of asparagine, GDP-mannose, and trehalose and the catabolic process of raffinose were activated. DEGs encoding antioxidants (spermidine) and antioxidase (CAT1, GPX4, DHAR2, and APX1) were much more up-regulated in embryos of KN27-3. The content of auxin (IAA), cis-zeatin riboside (cZR), and trans-zeatin riboside (tZR) in KN27-3 are higher than that in XLZ38 at five stages (from 12 h to 54 h). GA3 was expressed at a higher level in KN27-3 from 18 h to 54 h post imbibition compared to that in XLZ38. And abscisic acid (ABA) content of KN27-3 is lower than that in XLZ38 at five stages. Results from hormone content measurements and the related gene expression analysis indicated that IAA, CTK, and GA3 may promote germination of the cold-tolerant variety, while ABA inhibits it. These results expand the understanding of cottonseed germination and physiological regulations under chilling conditions by multiple pathways.

Low temperature tolerance at early growth stage of maize hybrids released in the 1970s–2000s

“…The GA 3 can induce amylase synthesis to provide energy that fuels embryonic development and promotes seed germination (Wang, Cui, et al, 2018) as well as regulates antioxidant activities to reduce ROS (Kim et al, 2016). Shen et al (2020) reported that IAA and cytokinin can accelerate seed germination under LT stress and that ABA can slow seed germination, but IAA and ABA were not significantly correlated with mean germination time. Abscisic acid was previously shown to be important in improving LT tolerance (Rubio & Pérez, 2019), which, however, was not clearly T A B L E 3 Significance for the effects of temperature (T), hybrid (H), and their interactions on root length, shoot length and the ratio of shoot and root length (R/S ratio) of maize hybrids released in 1970s-2000s grown under 15/10°C 12 h/12 h for 32 d and then transferred to 25/20°C 12 h/12 h or remaining at 15/10°C 12 h/12 h for another 10 d in Trial 3 (see Figure 1) confirmed in the present study.…”

Transcriptomic Profiling of Young Cotyledons Response to Chilling Stress in Two Contrasting Cotton (Gossypium hirsutum L.) Genotypes at the Seedling Stage

“…Transcriptome technology has been used to reveal differences in the molecular mechanisms of cold tolerance among different varieties [33,[50][51][52][53]. Previous studies have shown that there are more constitutive expression genes in the tolerant variety than the sensitive one before cold stress treatment [54,55].…”

“…In rice, transcriptomic analysis has been used to study the cold response mechanisms of leaves, roots, and shoots at the seedling stage, as well as anthers at the reproductive stage [30][31][32]. Recently, scientists have studied the cold response mechanisms of true cotton leaves at the seedling stage and seed embryos at the germination stage by using RNA-seq technology [3,33]. However, reports on the transcriptome profiling of cotton seedling cotyledons under cold stress had not been disclosed.…”

“…They are not only the essential autotrophic organs before the first true leaf appeared but also the most vulnerable parts to cold stress. Previous studies on the response of cotton to cold stress mainly focused on the germination stage of seeds and the true leaf stage of seedlings [3,33]. However, the seedling cotyledons are more susceptible to cold stress than true leaves.…”

Plant Cell and Organism Development

“…In their article, Shen et al [30] offer a comparative transcriptome analysis in the context of Gossypium hirsutum (upland cotton) seed germination in response to chilling stress. The authors selected two varieties of cotton that respond to this kind of stress in significantly different ways, i.e., KN27-3 (tolerant) and XLZ38 (susceptible).…”