A GARP transcription factor anther dehiscence defected 1 (OsADD1) regulates rice anther dehiscence

OsKANADI1 and OsYABBY5 regulate rice plant height by targeting GIBERELLIN 2-OXIDASE6

Plant height is an important agronomic characteristic of rice (Oryza sativa L.). Map-based cloning analyses of a natural semi-dwarf rice mutant with inwardly curled leaves found in the field revealed that the defects were due to a mutation of a SHAQKYF-class MYB family transcription factor, OsKANADI1 (OsKAN1). OsKAN1 directly bound to the OsYABBY5 (OsYAB5) promoter to repress its expression and interacted with OsYAB5 to form a functional OsKAN1-OsYAB5 complex. GIBERELLIN 2-OXIDASE6 (OsGA2ox6), encoding an enzyme in the gibberellin (GA) catabolic pathway, was activated by OsYAB5. Furthermore, the OsKAN1-OsYAB5 complex suppressed the inhibitory effect of OsKAN1 toward OsYAB5 and inhibited OsYAB5-induced OsGA2ox6 expression. The proOsKAN1:OsYAB5 transgenic plants were taller than wild-type plants, whereas oskan1 proOsKAN1:OsYAB5 plants exhibited a severe dwarf phenotype due to the absence of the OsKAN1-OsYAB5 complex. The OsKAN1-OsYAB5 complex modulated OsGA2ox6 expression, thereby regulating the levels of bioactive gibberellins and, consequently, plant height. This study elucidated the mechanism underlying the effect of the OsKAN1-OsYAB5-OsGA2ox6 regulatory pathway on plant height at different positions in rice stems and provided insights on stem development and candidate genes for the aerial architecture improvement of crop plants.

A genome‑wide approach to the systematic and comprehensive analysis of LIM gene family in sorghum (Sorghum bicolor L.)

The LIM domain-containing proteins are dominantly found in plants and play a significant role in various biological processes such as gene transcription as well as actin cytoskeletal organization. Nevertheless, genome-wide identification as well as functional analysis of the LIM gene family have not yet been reported in the economically important plant sorghum (Sorghum bicolor L.). Therefore, we conducted an in silico identification and characterization of LIM genes in S. bicolor genome using integrated bioinformatics approaches. Based on phylogenetic tree analysis and conserved domain, we identified five LIM genes in S. bicolor (SbLIM) genome corresponding to Arabidopsis LIM (AtLIM) genes. The conserved domain, motif as well as gene structure analyses of the SbLIM gene family showed the similarity within the SbLIM and AtLIM members. The gene ontology (GO) enrichment study revealed that the candidate LIM genes are directly involved in cytoskeletal organization and various other important biological as well as molecular pathways. Some important families of regulating transcription factors such as ERF, MYB, WRKY, NAC, bZIP, C2H2, Dof, and G2-like were detected by analyzing their interaction network with identified SbLIM genes. The cis-acting regulatory elements related to predicted SbLIM genes were identified as responsive to light, hormones, stress, and other functions. The present study will provide valuable useful information about LIM genes in sorghum which would pave the way for the future study of functional pathways of candidate SbLIM genes as well as their regulatory factors in wet-lab experiments.

The G2-Like gene family in Populus trichocarpa: identification, evolution and expression profiles

The Golden2-like (GLK) transcription factors are plant-specific transcription factors (TFs) that perform extensive and significant roles in regulating chloroplast development. Here, genome-wide identification, classification, conserved motifs, cis-elements, chromosomal locations, evolution and expression patterns of the PtGLK genes in the woody model plant Populus trichocarpa were analyzed in detail. In total, 55 putative PtGLKs (PtGLK1-PtGLK55) were identified and divided into 11 distinct subfamilies according to the gene structure, motif composition and phylogenetic analysis. Synteny analysis showed that 22 orthologous pairs and highly conservation between regions of GLK genes across P. trichocarpa and Arabidopsis were identified. Furthermore, analysis of the duplication events and divergence times provided insight into the evolutionary patterns of GLK genes. The previously published transcriptome data indicated that PtGLK genes exhibited distinct expression patterns in various tissues and different stages. Additionally, several PtGLKs were significantly upregulated under the responses of cold stress, osmotic stress, and methyl jasmonate (MeJA) and gibberellic acid (GA) treatments, implying that they might take part in abiotic stress and phytohormone responses. Overall, our results provide comprehensive information on the PtGLK gene family and elucidate the potential functional characterization of PtGLK genes in P. trichocarpa.

Genome-Wide Identification and Characterization of G2-Like Transcription Factor Genes in Moso Bamboo (Phyllostachys edulis)

G2-like (GLK) transcription factors contribute significantly and extensively in regulating chloroplast growth and development in plants. This study investigated the genome-wide identification, phylogenetic relationships, conserved motifs, promoter cis-elements, MCScanX, divergence times, and expression profile analysis of PeGLK genes in moso bamboo (Phyllostachys edulis). Overall, 78 putative PeGLKs (PeGLK1–PeGLK78) were identified and divided into 13 distinct subfamilies. Each subfamily contains members displaying similar gene structure and motif composition. By synteny analysis, 42 orthologous pairs and highly conserved microsynteny between regions of GLK genes across moso bamboo and maize were found. Furthermore, an analysis of the divergence times indicated that PeGLK genes had a duplication event around 15 million years ago (MYA) and a divergence happened around 38 MYA between PeGLK and ZmGLK. Tissue-specific expression analysis showed that PeGLK genes presented distinct expression profiles in various tissues, and many members were highly expressed in leaves. Additionally, several PeGLKs were significantly up-regulated under cold stress, osmotic stress, and MeJA and GA treatment, implying that they have a likelihood of affecting abiotic stress and phytohormone responses in plants. The results of this study provide a comprehensive understanding of the moso bamboo GLK gene family, as well as elucidating the potential functional characterization of PeGLK genes.

A cascade of bHLH-regulated pathways programs maize anther development

The spatiotemporal development of somatic tissues of the anther lobe is necessary for successful fertile pollen production. This process is mediated by many transcription factors acting through complex, multi-layered networks. Here, our analysis of functional knockout mutants of interacting basic helix-loop-helix genes Ms23, Ms32, basic helix-loop-helix 122 (bHLH122), and bHLH51 in maize (Zea mays) established that male fertility requires all four genes, expressed sequentially in the tapetum (TP). Not only do they regulate each other, but also they encode proteins that form heterodimers that act collaboratively to guide many cellular processes at specific developmental stages. MS23 is confirmed to be the master factor, as the ms23 mutant showed the earliest developmental defect, cytologically visible in the TP, with the most drastic alterations in premeiotic gene expression observed in ms23 anthers. Notably, the male-sterile ms23, ms32, and bhlh122-1 mutants lack 24-nt phased secondary small interfering RNAs (phasiRNAs) and the precursor transcripts from the corresponding 24-PHAS loci, while the bhlh51-1 mutant has wild-type levels of both precursors and small RNA products. Multiple lines of evidence suggest that 24-nt phasiRNA biogenesis primarily occurs downstream of MS23 and MS32, both of which directly activate Dcl5 and are required for most 24-PHAS transcription, with bHLH122 playing a distinct role in 24-PHAS transcription.

Genome-wide characterization and analysis of Golden 2-Like transcription factors related to leaf chlorophyll synthesis in diploid and triploid Eucalyptus urophylla

Golden 2-Like (GLK) transcription factors play a crucial role in chloroplast development and chlorophyll synthesis in many plant taxa. To date, no systematic analysis of GLK transcription factors in tree species has been conducted. In this study, 40 EgrGLK genes in the Eucalyptus grandis genome were identified and divided into seven groups based on the gene structure and motif composition. The EgrGLK genes were mapped to 11 chromosomes and the distribution of genes on chromosome was uneven. Phylogenetic analysis of GLK proteins between E. grandis and other species provided information for the high evolutionary conservation of GLK genes among different species. Prediction of cis-regulatory elements indicated that the EgrGLK genes were involved in development, light response, and hormone response. Based on the finding that the content of chlorophyll in mature leaves was the highest, and leaf chlorophyll content of triploid Eucalyptus urophylla was higher than that of the diploid control, EgrGLK expression pattern in leaves of triploid and diploid E. urophylla was examined by means of transcriptome analysis. Differential expression of EgrGLK genes in leaves of E. urophylla of different ploidies was consistent with the trend in chlorophyll content. To further explore the relationship between EgrGLK expression and chlorophyll synthesis, co-expression networks were generated, which indicated that EgrGLK genes may have a positive regulatory relationship with chlorophyll synthesis. In addition, three EgrGLK genes that may play an important role in chlorophyll synthesis were identified in the co-expression networks. And the prediction of miRNAs targeting EgrGLK genes showed that miRNAs might play an important role in the regulation of EgrGLK gene expression. This research provides valuable information for further functional characterization of GLK genes in Eucalyptus.

Identification of the Golden-2-like transcription factors gene family in Gossypium hirsutum

Background

Golden2-Like (GLK) transcription factors are a type of transcriptional regulator in plants. They play a pivotal role in the plant physiological activity process and abiotic stress response.

Methods

In this study, the potential function of GLK family genes in Gossypium hirsutum was studied based on genomic identification, phylogenetic analysis, chromosome mapping and cis-regulatory elements prediction. Gene expression of nine key genes were analyzed by qRT-PCR experiments.

Results

Herein, we identified a total of 146 GhGLK genes in Gossypium hirsutum, which were unevenly distributed on each of the chromosomes. There were significant differences in the number and location of genes between the At sub-genome and the Dt sub-genome. According to the phylogenetic analysis, they were divided into ten subgroups, each of which had very similar number and structure of exons and introns. Some cis-regulatory elements were identified through promoter analysis, including five types of elements related to abiotic stress response, five types of elements related to phytohormone and five types of elements involved in growth and development. Based on public transcriptome data analysis, we identified nine key GhGLKs involved in salt, cold, and drought stress. The qRT-PCR results showed that these genes had different expression patterns under these stress conditions, suggesting that GhGLK genes played an important role in abiotic stress response. This study laid a theoretical foundation for the screening and functional verification of genes related to stress resistance of GLK gene family in cotton.

Genome-Wide Analysis of the G2-Like Transcription Factor Genes and Their Expression in Different Senescence Stages of Tobacco (Nicotiana tabacum L.)

The Golden2-like (GLK) transcription factors play important roles in regulating chloroplast growth, development, and senescence in plants. In this study, a total of 89 NtGLK genes (NtGLK1-NtGLK89) were identified in the tobacco genome and were classified into 10 subfamilies with variable numbers of exons and similar structural organizations based on the gene structure and protein motif analyses. Twelve segmental duplication pairs of NtGLK genes were identified in the genome. These NtGLK genes contain two conserved helix regions related to the HLH structure, and the sequences of the first helix region are less conserved than that of the second helix motif. Cis-regulatory elements of the NtGLK promoters were widely involved in light responsiveness, hormone treatment, and physiological stress. Moreover, a total of 206 GLK genes from tomato, tobacco, maize, rice, and Arabidopsis were retrieved and clustered into eight subgroups. Our gene expression analysis indicated that NtGLK genes showed differential expression patterns in tobacco leaves at five senescence stages. The expression levels of six NtGLK genes in group C were reduced, coinciding precisely with the increment of the degree of senescence, which might be associated with the function of leaf senescence of tobacco. Our results have revealed valuable information for further functional characterization of the GLK gene family in tobacco.