Phospho-Mutant Activity Assays Provide Evidence for the Negative Regulation of Transcriptional Regulator PRE1 by Phosphorylation

Cell elongation and altered phytohormone levels play a role in establishing distyly in Averrhoa carambola

The flowers of distylous plants exhibit two distinct morphologies that facilitate precise pollen transfer. Averrhoa carambola, a woody plant characterized by distyly, has an unclear molecular regulatory mechanism underlying this trait. Its prolonged flowering period and substantial flower production render it an excellent model for investigating the distylous syndrome. This study aims to elucidate the mechanism of distyly in A. carambola and to identify the regulatory genes. The long-style cultivar 'Daguo Tianyangtao 1' and the short-style cultivar 'Daguo Tianyangtao 3' were selected as models for this investigation. We examined phenotypic characteristics, anatomical structures, and endogenous hormone content associated with distyly. Transcriptomic data were utilized to pinpoint candidate genes involved in the regulation of distyly, followed by a bioinformatics analysis these genes. The results indicate that variations in cell elongation contribute to the differential heights of stigmas and anthers in A. carambola, thereby resulting in the distylous syndrome. Auxins, Gibberellin A3 (GA3), Gibberellin A4 (GA4), and brassinolide (BL) were found to influence elongation of styles, whereas Gibberellin A1 (GA1) and GA4 affected filament elongation. Transcriptome sequencing analysis identified 34 hormone-related differentially expressed genes (DEGs) and 16 cell development-related DEGs in different morphs of pistils, and 29 hormone-related DEGs and 22 cell development-related DEGs were identified in different morphs of stamens. Four candidate genes-AcaBRU1, AcaPRE1, AcaXTH2, and AcaEXPA11-were found to possess conserved motifs characteristic of their respective families. Consequently, various plant hormones modulate the expression of response genes, leading to differences in elongation of style and filament cells between different flower types of A. carambola, thereby promoting the distylous syndrome. This study provides a theoretical basis for understanding the mechanisms of distyly formation in woody plants.

TARGET OF MONOPTEROS: key transcription factors orchestrating plant development and environmental response

Plants have an incredible ability to sustain root and vascular growth after initiation of the embryonic root and the specification of vascular tissue in early embryos. Microarray assays have revealed that a group of transcription factors, TARGET OF MONOPTEROS (TMO), are important for embryonic root initiation in Arabidopsis. Despite the discovery of their auxin responsiveness early on, their function and mode of action remained unknown for many years. The advent of genome editing has accelerated the study of TMO transcription factors, revealing novel functions for biological processes such as vascular development, root system architecture, and response to environmental cues. This review covers recent achievements in understanding the developmental function and the genetic mode of action of TMO transcription factors in Arabidopsis and other plant species. We highlight the transcriptional and post-transcriptional regulation of TMO transcription factors in relation to their function, mainly in Arabidopsis. Finally, we provide suggestions for further research and potential applications in plant genetic engineering.