Induced ovule-to-flower switch by interfering with SlIMA activity in tomato

The emerging functions of mini zinc finger (MIF) microproteins in seed plants: A minireview

Mini zinc fingers constitute a class of microproteins that appeared early in evolution and expanded in seeds plants. In this review, the phylogenetic history, the functions and the mode of action of Mini zinc fingers in plants are reported and discussed. It appears that mini zinc fingers play an important role in the control of plant development. They are involved in the control of cell division and expansion, in the switch between the determinate/indeterminate state of the meristems and in the regulation of vegetative growth and floral organ development. Their biochemical mode of action seems to be diverse. In some studies, it has been reported that mini zinc fingers can directly bind to DNA and activate target gene expression, whereas other studies have shown that they can interact with and inhibit the activity of specific zinc finger homeodomain transcription factors or act as adaptor proteins necessary to aggregate polymeric protein complexes corresponding to chromatin remodelling factors negatively regulating the expression of specific genes. The diversity of mode of action for mini zinc finger microproteins suggests a wider range of biological functions than what has been that described in the literature thus far, and their involvement in the response to biotic and abiotic stresses should be further investigated in future studies.

New Advances in the Study of Regulation of Tomato Flowering-Related Genes Using Biotechnological Approaches

The tomato is a convenient object for studying reproductive processes, which has become a classic. Such complex processes as flowering and fruit setting require an understanding of the fundamental principles of molecular interaction, the structures of genes and proteins, the construction of signaling pathways for transcription regulation, including the synchronous actions of cis-regulatory elements (promoter and enhancer), trans-regulatory elements (transcription factors and regulatory RNAs), and transposable elements and epigenetic regulators (DNA methylation and acetylation, chromatin structure). Here, we discuss the current state of research on tomatoes (2017-2023) devoted to studying the function of genes that regulate flowering and signal regulation systems using genome-editing technologies, RNA interference gene silencing, and gene overexpression, including heterologous expression. Although the central candidate genes for these regulatory components have been identified, a complete picture of their relationship has yet to be formed. Therefore, this review summarizes the latest achievements related to studying the processes of flowering and fruit set. This work attempts to display the gene interaction scheme to better understand the events under consideration.

Zinc Finger-Homeodomain and Mini Zinc Finger proteins are key players in plant growth and responses to environmental stresses

The ZINC FINGER-HOMEODOMAIN (ZHD) protein family is a plant-specific family of transcription factors containing two conserved motifs: a non-canonical C5H3 zinc finger domain (ZF) and a DNA-binding homeodomain (HD). The MINI ZINC FINGER (MIF) proteins belong to this family, but were possibly derived from the ZHDs by losing the HD. Information regarding the function of ZHD and MIF proteins is scarce. However, different studies have shown that ZHD/MIF proteins play important roles not only in plant growth and development, but also in response to environmental stresses, including drought and pathogen attack. Here we review recent advances relative to ZHD/MIF functions in multiple species, to provide new insights into the diverse roles of these transcription factors in plants. Their mechanism of action in relation to their ability to interact with other proteins and DNA is also discussed. We then propose directions for future studies to understand better their important roles and pinpoint strategies for potential applications in crop improvement.

Identification of Potential Gene Regulatory Pathways Affecting the Ratio of Four-Seed Pod in Soybean

The number of four-seed pods is one of the most important agronomic traits affected by gene and environment that can potentially improve soybean (Glycine max) yield. However, the gene regulatory network that affects the ratio of four-seed pod (the ratio of the number of four-seed pods to the total number of pods in each individual plant) is yet unclear. Here, we performed bulked segregant RNA sequencing (BSR-seq) on a series of recombinant inbred lines (RILs) derived from hybrid progenies between Heinong 48 (HN48), a cultivar with a high ratio of four-seed pod, and Henong 64 (HN64), a cultivar with a low ratio of four-seed pod. Two tissues, flower bud and young pod, at two different growth stages, R1 and R3, were analyzed under the ratios of four-seed pod at less than 10% and greater than 30%, respectively. To identify the potential gene regulation pathways associated with the ratio of soybean four-seed pod, we performed differentially expressed analysis on the four bulked groups. A differentially expressed gene (DEG) encoding a photosystem II 5-kDa protein had the function of participating in the energy conversion of photosynthesis. In addition, 79 common DEGs were identified at different developmental stages and under different ratios of four-seed pod. Among them, four genes encoding calcium-binding proteins and a WRKY transcription factor were enriched in the plant-pathogen interaction pathway, and they showed a high level of expression in roots. Moreover, 10 DEGs were identified in the reported quantitative trait locus (QTL) interval of four-seed pod, and two of them were significantly enriched in the pentose and glucuronate interconversion pathway. These findings provide basic insights into the understanding of the underlying gene regulatory network affected by specific environment and lay the foundation for identifying the targets that affect the ratio of four-seed pod in soybean.

The VvSUPERMAN-like Gene Is Differentially Expressed between Bicarpellate and Tricarpellate Florets of Vitis vinifera L. Cv. 'Xiangfei' and Its Heterologous Expression Reduces Carpel Number in Tomato

Multicarpellate fruits are larger and produce more seeds than mono- or bicarpellate fruits, enhancing the reproductive capacity of the plant. To identify the phenotypic and molecular differences among florets of different carpel types, we studied carpel formation and fusion in the grapevine (Vitis vinifera) cultivar 'Xiangfei', which produces a high proportion of multicarpellate fruit. We also determined the function of VvSUPERMAN-like (VvSUP-like) and explored its relationship with VvWUS (VvWUSCHEL) and VvAG1 (VvAGAMOUS), which is related to the formation of carpel primordia. We showed that carpel formation and fusion were largely consistent between bicarpellate and tricarpellate ovaries, which both involve congenital fusion; rather, the differences between these ovary types arose from variation in carpel primordia number and location. Transgenic tomato (Solanum lycopersicum) plants expressing VvSUP-like produced significantly fewer carpels and other floral organs than the wild type. Moreover, transcriptome sequencing results indicate that VvSUP-like was more highly expressed in bicarpellate than in tricarpellate 'Xiangfei' florets. Luciferase reporter assays indicated that VvSUP-like inhibits the expression of VvAG1 and VvWUS by directly binding to their promoters, and VvWUS promotes VvAG1 expression by directly binding to its promoter. VvSUP-like inhibits the feedback signaling between VvWUS and VvAG1. Together, these results suggest that VvSUP-like negatively regulates the number of carpels that develop by inhibiting VvAG1 and VvWUS expression.

OsHDA710-Mediated Histone Deacetylation Regulates Callus Formation of Rice Mature Embryo

Histone deacetylases (HDACs) play important roles in the regulation of eukaryotic gene expression. The role of HDACs in specialized transcriptional regulation and biological processes is poorly understood. In this study, we evaluated the global expression patterns of genes related to epigenetic modifications during callus initiation in rice. We found that the repression of HDAC activity by trichostatin A (TSA) or by OsHDA710 mutation (hda710) results in impaired callus formation of rice mature embryo and increased global histone H3 acetylation levels. The HDAC inhibition decreased auxin response and cell proliferation in callus formation. Meanwhile, the transcriptional repressors OsARF18 and OsARF22 were upregulated in the callus of hda710. The chromatin immunoprecipitation-quantitative PCR (ChIP-qPCR) analysis demonstrated that the callus of hda710 exhibited enhanced histone H3 acetylation levels at the chromatin regions of OsARF18 and OsARF22. Furthermore, we found that OsARF18 and OsARF22 were regulated through OsHDA710 recruitment to their target loci. In addition, overexpression of OsARF18 decreased the transcription of downstream genes PLT1 and PLT2 and inhibited callus formation of the mature embryo. These results demonstrate that OsHDA710 regulates callus formation by suppressing repressive OsARFs via histone deacetylation during callus formation of rice mature embryo. This indicates that OsHDA710-mediated histone deacetylation is an epigenetic regulation pathway for maintaining auxin response during cell dedifferentiation.