GhGASA10-1 promotes the cell elongation in fiber development through the phytohormones IAA-induced

GhGASA14 regulates the flowering time of upland cotton in response to GA3

KEY MESSAGE

The silencing of GhGASA14 and the identification of superior allelic variation in its coding region indicate that GhGASA14 may positively regulate flowering and the response to GA3. Gibberellic acid-stimulated Arabidopsis (GASA), a member of the gibberellin-regulated short amino acid family, has been extensively investigated in several plant species and found to be critical for plant growth and development. However, research on this topic in cotton has been limited. In this study, we identified 38 GhGASAs that were dispersed across 18 chromosomes in upland cotton, and all of these genes had a GASA core domain. Transcriptome expression patterns and qRT-PCR results revealed that GhGASA9 and GhGASA14 exhibited upregulated expression not only in the floral organs but also in the leaves of early-maturing cultivars. The two genes were functionally characterized by virus-induced gene silencing (VIGS), and the budding and flowering times after silencing the target genes were later than those of the control (TRV:00). Compared with that in the water-treated group (MOCK), the flowering period of the different fruiting branches in the GA3-treated group was more concentrated. Interestingly, allelic variation was detected in the coding sequence of GhGASA14 between early-maturing and late-maturing accessions, and the frequency of this favorable allele was greater in high-latitude cotton cultivars than in low-latitude ones. Additionally, a significant linear relationship was observed between the expression level of GhGASA14 and flowering time among the 12 upland cotton accessions. Taken together, these results indicated that GhGASA14 may positively regulate flowering time and respond to GA3. These findings could lead to the use of valuable genetic resources for breeding early-maturing cotton cultivars in the future.

Genome-wide association study for boll weight in Gossypium hirsutum races

High yield has always been an essential target in almost all of the cotton breeding programs. Boll weight (BW) is a key component of cotton yield. Numerous linkage mapping and genome-wide association studies (GWAS) have been performed to understand the genetic mechanism of BW, but information on the markers/genes controlling BW remains limited. In this study, we conducted a GWAS for BW using 51,268 high-quality single-nucleotide polymorphisms (SNPs) and 189 Gossypium hirsutum accessions across five different environments. A total of 55 SNPs significantly associated with BW were detected, of which 29 and 26 were distributed in the A and D subgenomes, respectively. Five SNPs were simultaneously detected in two environments. For TM5655, TM8662, TM36371, and TM50258, the BW grouped by alleles of each SNP was significantly different. The ± 550 kb regions around these four key SNPs contained 262 genes. Of them, Gh_A02G1473, Gh_A10G1765, and Gh_A02G1442 were expressed highly at 0 to 1 days post-anthesis (dpa), - 3 to 0 dpa, and - 3 to 0 dpa in ovule of TM-1, respectively. They were presumed as the candidate genes for fiber cell differentiation, initiation, or elongation based on gene annotation of their homologs. Overall, these results supplemented valuable information for dissecting the genetic architecture of BW and might help to improve cotton yield through molecular marker-assisted selection breeding and molecular design breeding.

Tomato miR156-targeted SlSBP15 represses shoot branching by modulating hormone dynamics and interacting with GOBLET and BRANCHED1b

The miRNA156 (miR156)/SQUAMOSA PROMOTER-BINDING PROTEIN-LIKE (SPL/SBP) regulatory hub is highly conserved among phylogenetically distinct species, but how it interconnects multiple pathways to converge to common integrators controlling shoot architecture is still unclear. Here, we demonstrated that the miR156/SlSBP15 node modulates tomato shoot branching by connecting multiple phytohormones with classical genetic pathways regulating both axillary bud development and outgrowth. miR156-overexpressing plants (156-OE) displayed high shoot branching, whereas plants overexpressing a miR156-resistant SlSBP15 allele (rSBP15) showed arrested shoot branching. Importantly, the rSBP15 allele was able to partially restore the wild-type shoot branching phenotype in the 156-OE background. rSBP15 plants have tiny axillary buds, and their activation is dependent on shoot apex-derived auxin transport inhibition. Hormonal measurements revealed that indole-3-acetic acid (IAA) and abscisic acid (ABA) concentrations were lower in 156-OE and higher in rSBP15 axillary buds, respectively. Genetic and molecular data indicated that SlSBP15 regulates axillary bud development and outgrowth by inhibiting auxin transport and GOBLET (GOB) activity, and by interacting with tomato BRANCHED1b (SlBRC1b) to control ABA levels within axillary buds. Collectively, our data provide a new mechanism by which the miR156/SPL/SBP hub regulates shoot branching, and suggest that modulating SlSBP15 activity might have potential applications in shaping tomato shoot architecture.

Rhizobium Soaking Promoted Maize Growth by Altering Rhizosphere Microbiomes and Associated Functional Genes

Rhizobium is a Gram-negative bacterium, which dissolves minerals, produces growth hormones, promotes root growth, and protects plants from different soil-borne pathogens. In the present study, roots, stalks, and fresh weight of maize (Zea mays L.) were significantly increased after soaking in Bradyrhizobium japonicum compared with the control. Subsequently, transcriptome sequencing results of the whole maize plant soaked in B. japonicum showed that multiple growth and development-related genes were up-regulated more than 100-fold compared to the control. Furthermore, the abundance of plant growth promoting bacteria, such as Acidobacteria Subgroup_6 and Chloroflexi KD4-96, were increased significantly. On the contrary, the abundance of multiple pathogens, such as Curvularia, Fusarium and Mycocentrospora, were significantly decreased. Moreover, inoculation with B. japonicum could inhibit the infection of the pathogen Fusarium graminearum in maize. These results suggest that soaking seeds in B. japonicum may affect the expression of maize growth and development-related genes as the bacteria changes the soil microorganism community structure. These findings may help to expand the application of B. japonicum in crop production and provide new opportunities for food security.

Genome-wide identification and characterization of the lettuce GASA family in response to abiotic stresses

BACKGROUND

Lettuce is one of the most extensively farmed vegetables in the world, and it prefers cool growing conditions. High temperatures promote premature bolt formation, reducing quality and yield. The gibberellic acid-stimulated Arabidopsis (GASA) family genes play critical roles in plant growth, development, and stress responses. However, the biological functions of GASA proteins in lettuce have yet to be thoroughly investigated.

RESULTS

Using genome-wide analysis, 20 GASAs were identified in lettuce including, three groups of LsGASA proteins based on the phylogenetic analysis. Except for one, all GASA proteins included a conserved GASA domain with 12 cysteine residues. Cis-element analysis showed that LsGASAs were closely associated with light, phytohormones, and stress resistance. Five segmental and three tandem duplication events were observed in the LsGASA family based on duplication analysis. GASA synteny analysis among lettuce, Arabidopsis, tobacco, and rice revealed that LsGASA5 is highly collinear with all species. Six of the 20 LsGASA showed increased expression patterns at specific time points in the shoot apical meristem when subjected to heat stress. According to gene expression analysis, the majority of GASA were highly expressed in flowers compared to other organs, and six GASA exhibited highly increased expression levels in response to NaCl, abscisic acid, and gibberellin treatment. Furthermore, LsGASA proteins are predominantly found in the plasma membrane and/or the cytosol.

CONCLUSIONS

This study provides a comprehensive characterization of LsGASA genes for their diversity and biological functions. Moreover, our results will be useful for further studies on the function of lettuce GASA in abiotic stress- and heat-induced bolting signaling.

The study on interacting factors and functions of GASA6 in Jatropha curcas L

BACKGROUND

The gibberellic acid-stimulated Arabidopsis (GASA) gene encodes a class of cysteine-rich functional proteins and is ubiquitous in plants. Most GASA proteins are influence the signal transmission of plant hormones and regulate plant growth and development, however, their function in Jatropha curcas is still unknown.

RESULTS

In this study, we cloned JcGASA6, a member of the GASA family, from J. curcas. The JcGASA6 protein has a GASA-conserved domain and is located in the tonoplast. The three-dimensional structure of the JcGASA6 protein is highly consistent with the antibacterial protein Snakin-1. Additionally, the results of the yeast one-hybrid (Y1H) assay showed that JcGASA6 was activated by JcERF1, JcPYL9, and JcFLX. The results of the Y2H assay showed that both JcCNR8 and JcSIZ1 could interact with JcGASA6 in the nucleus. The expression of JcGASA6 increased continuously during male flower development, and the overexpression of JcGASA6 was associated with filament elongation of the stamens in tobacco.

CONCLUSION

JcGASA6, a member of the GASA family in J. curcas, play an important role in growth regulation and floral development (especially in male flower). It is also involved in the signal transduction of hormones, such as ABA, ET, GA, BR, and SA. Also, JcGASA6 is a potential antimicrobial protein determined by its three-dimensional structure.

Molecular Regulation of Cotton Fiber Development: A Review

Cotton (Gossypium spp.) is an economically important natural fiber crop. The quality of cotton fiber has a substantial effect on the quality of cotton textiles. The identification of cotton fiber development-related genes and exploration of their biological functions will not only enhance our understanding of the elongation and developmental mechanisms of cotton fibers but also provide insights that could aid the cultivation of new cotton varieties with improved fiber quality. Cotton fibers are single cells that have been differentiated from the ovule epidermis and serve as a model system for research on single-cell differentiation, growth, and fiber production. Genes and fiber formation mechanisms are examined in this review to shed new light on how important phytohormones, transcription factors, proteins, and genes linked to fiber development work together. Plant hormones, which occur in low quantities, play a critically important role in regulating cotton fiber development. Here, we review recent research that has greatly contributed to our understanding of the roles of different phytohormones in fiber development and regulation. We discuss the mechanisms by which phytohormones regulate the initiation and elongation of fiber cells in cotton, as well as the identification of genes involved in hormone biosynthetic and signaling pathways that regulate the initiation, elongation, and development of cotton fibers.

Identification and Expression Analysis of the Populus trichocarpa GASA-Gene Family

The gibberellic acid-stimulated Arabidopsis (GASA) gene family plays an important regulatory role in the growth and development of plants. In this study, we identified 19 GASA genes using bioinformatics-based methods in Populus trichocarpa, and these PtGASA genes could be divided into three categories based on their phylogenetic relationships. Based on an analysis of the structure and motifs of these genes, it was concluded that PtGASA class II members are more conserved than class I and class III members are, and the results of collinearity analysis showed that members of class II are collinearly related in poplar. Expression analysis of Populus trichocarpa roots, stems, and leaves showed that most of the PtGASA genes are expressed at higher levels in the stems or roots than in the leaves; a similar expression pattern was found in Vitis vinifera, indicating that the GASA-family members mainly play a role in the morphogenesis of poplar. Considering the phenomenon of gene amplification, we found that the higher the similarity of homologous genes was, the more similar the expression patterns. This study represents the first whole-genome identification and expression-profile analysis of the GASA-gene family in poplar, a model species, laying a foundation for functional studies of poplar GASA genes and serving as a reference for related research on other woody plant species.