The objective of this study was to increase understanding about the mechanism by which polyamines (PAs) promote the conversion of embryogenic calli (EC) into somatic embryos in cotton (Gossypium hirsutum L.). We measured the levels of endogenous PAs and H2O2, quantified the expression levels of genes involved in the PAs pathway at various stages of cotton somatic embryogenesis (SE), and investigated the effects of exogenous PAs and H2O2 on differentiation and development of EC. Putrescine (Put), spermidine (Spd), and spermine (Spm) significantly increased from the EC stage to the early phase of embryo differentiation. The levels of Put then decreased until the somatic embryo stage whereas Spd and Spm remained nearly the same. The expression profiles of GhADC genes were consistent with changes in Put during cotton SE. The H2O2 concentrations began to increase significantly at the EC stage, during which time both GhPAO1 and GhPAO4 expressions were highest and PAO activity was significantly increased. Exogenous Put, Spd, Spm, and H2O2 not only enhanced embryogenic callus growth and embryo formation, but also alleviated the effects of D-arginine and 1, 8-diamino-octane, which are inhibitors of PA synthesis and PAO activity. Overall, the results suggest that both PAs and their metabolic product H2O2 are essential for the conversion of EC into somatic embryos in cotton.
Background: Male sterility is an efficient trait for hybrid seed production and germplasm innovation. Until now, most studies on male sterility were on cytoplasmic and recessive genic sterility, with few on dominant genic male sterility, especially in cotton, due to lack of such mutant. Results: We discovered a natural male sterile (MS) Sea Island cotton (G. barbadense) mutant. Genetic analysis showed the mutation was caused by a dominant mutation in a single nuclear gene. Comparative cytological observation of anther sections from MS and wild-type (WT) uncovered cellular differences in anther at and after the tetrad stage of pollen mother cells (PMC). In the MS anthers, the outer wall of pollen grains was free of spinules, the tapetum was vacuolated and showed delayed degradation, consequently, no functional pollen grains. Comparison of transcriptomes from meiosis, tetrad, mononuclear and binuclear pollen, and pollen maturation stages identified 13,783 non-redundant differentially expressed genes (DEGs) between MS and WT. Based on the number of DEGs, analyses of enriched GO terms and KEGG pathways, it was evident that significant transcriptomic changes occurred at and after the tetrad stage, consistent with cytological observation, and that the major differences were on metabolism of starch, sucrose, ascorbate, aldarate, alanine, aspartate and glutamate, and biosynthesis of cutin, suberine and wax. WGCNA analysis identified five modules containing 920 genes highly related to anther development, especially the greenyellow module with 54 genes that was highly associated with PMC meiosis and tetrad formation. A NAC transcription factor (Gh_D11G2469) was identified as a hub gene for this module, which warrants further functional characterization. Conclusions: We demonstrated that the MS trait was controlled by a single dominant nuclear gene and caused by delayed tapetum degradation at the tetrad stage. Comparative transcriptome analysis and gene network construction identified DEGs, enriched GO terms and metabolic pathways, and hub genes potentially associated with anther development and the MS trait. These results contribute to our understanding of dominant genic male sterility (DGMS) and provided source for innovation of cotton germplasm.
Fatty acyl‐CoA reductases (FAR) are involved in plant wax synthesis and play important roles in plant growth and development. However, little information is available for cotton FAR genes. In this study, we carried out a genome‐wide identification of FAR genes in Upland cotton ( Gossypium hirsutum L.) and found 10 GhFARs that form five pairs of homoeologs ( GhFAR2A to GhFAR3 . 4D ) distributed on six chromosomes. The 10 GhFARs were separated into two subfamilies. Most GhFARs showed tissue‐specific expression patterns, and at least one GhFAR of each pair of homoeologs was relatively highly expressed in at least one of the tissues investigated. GhFAR3 . 1 was highly expressed in leaves. The function of GhFAR3.1 in wax accumulation and drought tolerance was analyzed using virus‐induced gene silencing (VIGS). Silencing GhFAR3 . 1 reduced the total wax content and relative water content of leaves by over 60% and 13%, respectively, suggesting a role of GhFAR3 . 1 in wax synthesis and protection against water loss. Compared to the well‐watered conditions, drought stress induced significant accumulation of wax in leaves of wild‐type plants but not in leaves of GhFAR3.1 silenced plants, leading to less water holding capacity in GhFAR3.1 silenced plants and plant wilting. Silencing GhFAR3 . 1 had no effect on the expression levels of the wax biosynthesis pathway genes KAS , KCS, and LACS (upstream GhFAR3 . 1 ), but reduced the transcript level of its downstream gene WSD . Together, these results suggest that leaf wax content is important for water retention and drought tolerance and that GhFAR3 . 1 is essential for wax synthesis in cotton leaves. These results also provide the basis for further study on the molecular regulation mechanism of GhFARs in cotton development and surface lipid synthesis.
Oifferent wheat genotypes were treated with gamma-rays, sodium azide (SA) and EMS betore tissue culture and immature embryos from M| plants or plants shortly after expostire to gamma-ra\'S were used to initiate eallus ctilture. Thotisantis ot plants '.'.ere regenerated and used to investigate tbe effeet ol mutagenic treatments on the regenerated plants and iomaclonal variation in the M,R: and M J
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.