Overexpression of the maize WRKY114 gene in transgenic rice reduce plant height by regulating the biosynthesis of GA

Unveiling the power of PavGID1s: the critical player in sweet cherry flower bud dormancy release

Exogenous hormones can regulate bud dormancy release, particularly in cases where inadequate winter chill accumulation due to global warming affects perennial plants. Gibberellin (GA) is recognized as a critical signal for dormancy release in woody perennials. This study explores the influence of GA and its signaling components on the dormancy release in sweet cherry. The external application of GA4 + 7 significantly promoted the bud break rate and dormancy release. Notably, there was a substantial accumulation of GA3, GA4, and GA7 in the buds, accompanied by a reduced concentration of abscisic acid (ABA) following GA treatment. RNA-Seq identified 8,610 differentially expressed transcripts in GA-treated buds compared to the Mock group. Transcriptome sequencing revealed differential expressions of PavGID1s, the GA receptor GID1, in sweet cherry flower buds after GA treatment. These findings were further verified across different seasons in sweet cherry. In both PavGID1b and PavGID1c, the open reading frame (ORF) is 1,032 bases long and encodes 344 amino acids. Overexpression of PavGID1b and PavGID1c resulted in early flowering and higher plants in Arabidopsis. However, these genes have opposing roles in seed germination in Arabidopsis. Furthermore, PavWRKY31 may regulate the stabilization and release of dormancy by modulating the transcriptional level of PavGID1c. PavGA20ox-2 and PavGID2 may also influence sweet cherry dormancy release by interacting with GID1s and affecting DELLA protein stability. These results provide a theoretical basis for understanding the regulatory effect of gibberellin on the bud dormancy of plants.

Maize ZmWRKY71 gene positively regulates drought tolerance through reactive oxygen species homeostasis

Drought stress severely affects plant growth and yield. The plant-specific WRKY transcription factors play an important role in regulating the plant response to abiotic stresses. In this study, we identified a group I WRKY gene from maize, designated ZmWRKY71. Real-time quantitative reverse transcription-PCR analysis revealed that ZmWRKY71 was predominantly expressed in the roots and was induced by drought. ZmWRKY71 was localized in the nucleus and showed transcriptional activity in yeast. Heterologous overexpression of ZmWRKY71 improved drought tolerance in yeast and Arabidopsis. Compared with the wild type, the overexpression lines showed a higher survival rate under drought stress with reduced malondialdehyde content and elevated antioxidant enzyme activities. In contrast, mutation of ZmWRKY71 in maize leads to increased sensitivity to drought stress, reduced survival, elevated concentrations of reactive oxygen species, and increased malondialdehyde content. RNA-sequencing analysis revealed that the expression patterns of genes associated with translation, membrane, and oxidoreductase activity pathways were altered under drought stress. Yeast one-hybrid, dual-luciferase, and electrophoretic mobility shift assays confirmed that ZmWRKY71 was capable of directly binding to the W-box element in the promoter region of ZmPOD42 (Zm00001eb330550). Taken together, the results show that ZmWRKY71 positively regulates maize drought tolerance. This research enriches the drought tolerance gene pool for maize and provides a theoretical basis for maize drought tolerance breeding.

Genome-wide identification of ZmMYC2 binding sites and target genes in maize

BACKGROUND

Jasmonate (JA) is the important phytohormone to regulate plant growth and adaption to stress signals. MYC2, an bHLH transcription factor, is the master regulator of JA signaling. Although MYC2 in maize has been identified, its function remains to be clarified.

RESULTS

To understand the function and regulatory mechanism of MYC2 in maize, the joint analysis of DAP-seq and RNA-seq is conducted to identify the binding sites and target genes of ZmMYC2. A total of 3183 genes are detected both in DAP-seq and RNA-seq data, potentially as the directly regulating genes of ZmMYC2. These genes are involved in various biological processes including plant growth and stress response. Besides the classic cis-elements like the G-box and E-box that are bound by MYC2, some new motifs are also revealed to be recognized by ZmMYC2, such as nGCATGCAnn, AAAAAAAA, CACGTGCGTGCG. The binding sites of many ZmMYC2 regulating genes are identified by IGV-sRNA.

CONCLUSIONS

All together, abundant target genes of ZmMYC2 are characterized with their binding sites, providing the basis to construct the regulatory network of ZmMYC2 and better understanding for JA signaling in maize.

Joint-GWAS, Linkage Mapping, and Transcriptome Analysis to Reveal the Genetic Basis of Plant Architecture-Related Traits in Maize

Plant architecture is one of the key factors affecting maize yield formation and can be divided into secondary traits, such as plant height (PH), ear height (EH), and leaf number (LN). It is a viable approach for exploiting genetic resources to improve plant density. In this study, one natural panel of 226 inbred lines and 150 family lines derived from the offspring of T32 crossed with Qi319 were genotyped by using the MaizeSNP50 chip and the genotyping by sequence (GBS) method and phenotyped under three different environments. Based on the results, a genome-wide association study (GWAS) and linkage mapping were analyzed by using the MLM and ICIM models, respectively. The results showed that 120 QTNs (quantitative trait nucleotides) and 32 QTL (quantitative trait loci) related to plant architecture were identified, including four QTL and 40 QTNs of PH, eight QTL and 41 QTNs of EH, and 20 QTL and 39 QTNs of LN. One dominant QTL, qLN7-2, was identified in the Zhangye environment. Six QTNs were commonly identified to be related to PH, EH, and LN in different environments. The candidate gene analysis revealed that Zm00001d021574 was involved in regulating plant architecture traits through the autophagy pathway, and Zm00001d044730 was predicted to interact with the male sterility-related gene ms26. These results provide abundant genetic resources for improving maize plant architecture traits by using approaches to biological breeding.

Important Factors Controlling Gibberellin Homeostasis in Plant Height Regulation

Plant height is an important agronomic trait that is closely associated with crop yield and quality. Gibberellins (GAs), a class of highly efficient plant growth regulators, play key roles in regulating plant height. Increasing reports indicate that transcriptional regulation is a major point of regulation of the GA pathways. Although substantial knowledge has been gained regarding GA biosynthetic and signaling pathways, important factors contributing to the regulatory mechanisms homeostatically controlling GA levels remain to be elucidated. Here, we provide an overview of current knowledge regarding the regulatory network involving transcription factors, noncoding RNAs, and histone modifications involved in GA pathways. We also discuss the mechanisms of interaction between GAs and other hormones in plant height development. Finally, future directions for applying knowledge of the GA hormone in crop breeding are described.

Overexpression of 9-cis-Epoxycarotenoid Dioxygenase Gene, IbNCED1, Negatively Regulates Plant Height in Transgenic Sweet Potato

Plant height is one of the key agronomic traits for improving the yield of sweet potato. Phytohormones, especially gibberellins (GAs), are crucial to regulate plant height. The enzyme 9-cis-epoxycarotenoid dioxygenase (NCED) is the key enzyme for abscisic acid (ABA) biosynthesis signalling in higher plants. However, its role in regulating plant height has not been reported to date. Here, we cloned a new NCED gene, IbNCED1, from the sweet potato cultivar Jishu26. This gene encoded the 587-amino acid polypeptide containing an NCED superfamily domain. The expression level of IbNCED1 was highest in the stem and the old tissues in the in vitro-grown and field-grown Jishu26, respectively. The expression of IbNCED1 was induced by ABA and GA3. Overexpression of IbNCED1 promoted the accumulation of ABA and inhibited the content of active GA3 and plant height and affected the expression levels of genes involved in the GA metabolic pathway. Exogenous application of GA3 could rescue the dwarf phenotype. In conclusion, we suggest that IbNCED1 regulates plant height and development by controlling the ABA and GA signalling pathways in transgenic sweet potato.

GA signaling protein LsRGL1 interacts with the abscisic acid signaling-related gene LsWRKY70 to affect the bolting of leaf lettuce

A variety of endogenous hormone signals, developmental cues, and environmental stressors can trigger and promote leaf lettuce bolting. One such factor is gibberellin (GA), which has been linked to bolting. However, the signaling pathways and the mechanisms that regulate the process have not been discussed in full detail. To clarify the potential role of GAs in leaf lettuce, significant enrichment of GA pathway genes was found by RNA-seq, among which the LsRGL1 gene was considered significant. Upon overexpression of LsRGL1, a noticeable inhibition of leaf lettuce bolting was observed, whereas its knockdown by RNA interference led to an increase in bolting. In situ hybridization analysis indicated a significant accumulation of LsRGL1 in the stem tip cells of overexpressing plants. Leaf lettuce plants stably expressing LsRGL1 were examined concerning differentially expressed genes through RNA-seq analysis, and the data indicated enhanced enrichment of these genes in the 'plant hormone signal transduction' and 'phenylpropanoid biosynthesis' pathways. Additionally, significant changes in LsWRKY70 gene expression were identified in COG (Clusters of Orthologous Groups) functional classification. The results of yeast one-hybrid, β-glucuronidase (GUS), and biolayer interferometry (BLI) experiments showed that LsRGL1 proteins directly bind to the LsWRKY70 promoter. Silencing LsWRKY70 by virus-induced gene silencing (VIGS) can delay bolting, regulate the expression of endogenous hormones, abscisic acid (ABA)-linked genes, and flowering genes, and improve the nutritional quality of leaf lettuce. These results strongly associate the positive regulation of bolting with LsWRKY70 by identifying its vital functions in the GA-mediated signaling pathway. The data obtained in this research are invaluable for further experiments concerning the development and growth of leaf lettuce.

Comparative Transcriptome Analysis of the Heterosis of Salt Tolerance in Inter-Subspecific Hybrid Rice

Soil salinity is one of the major abiotic stresses limiting rice growth. Hybrids outperform their parents in salt tolerance in rice, while its mechanism is not completely understood. In this study, a higher seedling survival was observed after salt treatment in an inter-subspecific hybrid rice, Zhegengyou1578 (ZGY1578), compared with its maternal japonica Zhegeng7A (ZG7A) and paternal indica Zhehui1578 (ZH1578). A total of 2584 and 3061 differentially expressed genes (DEGs) with at least twofold changes were identified between ZGY1578 and ZG7A and between ZGY1578 and ZH1578, respectively, in roots under salt stress using the RNA sequencing (RNA-Seq) approach. The expressions of a larger number of DEGs in hybrid were lower or higher than those of both parents. The DEGs associated with transcription factors, hormones, and reactive oxygen species (ROS)-related genes might be involved in the heterosis of salt tolerance. The expressions of the majority of transcription factors and ethylene-, auxin-, and gibberellin-related genes, as well as peroxidase genes, were significantly higher in the hybrid ZGY1578 compared with those of both parents. The identified genes provide valuable clues to elucidate the heterosis of salt tolerance in inter-subspecific hybrid rice.