Plant Communications最新文献

Awn plays a multifaceted role in the physiological and ecological processes that facilitate plant adaptation. Despite the predominance of awnless varieties in contemporary rice cultivation, this review elucidates historical, agricultural, and biological evidence demonstrating the retention of awns was prevalent until the first half of the last century in Asia. Furthermore, the subspecies of Geng (or japonica) and Xian (or indica) exhibit a distinct evolutionary trajectory, with the awn reduction in Geng occurring considerably later than that in Xian. The presence of awns could have provided ancient farmers with distinct advantages for rice cultivation, contingent upon environmental conditions and agricultural practices. These findings suggest that the reduction of awn is unlikely to be a trait that has been extensively selected during rice domestication. This assumption is particularly evident when considering the long-standing presence of awnless alleles within the gene pool, but these alleles are not fixed in the population. Since the early 20th century, the overwhelming elimination of awn has been associated with breeding practices aimed at achieving high yield. A substantial body of research has identified a negative correlation between the awn development and seed number. This review provides novel insights into the evolution of awns in rice and may also be of benefit to relevant research on other species.

The centromere is a specialized domain that facilitates chromosome segregation during mitosis and serves as the site of kinetochore formation. KINETOCHORE NULL2 (αKNL2) is essential for the recognition and loading of the centromeric histone H3 variant CENH3 at centromeres. A yeast two-hybrid screen for αKNL2 interactors identified components of the SUMOylation pathway. However, the role of αKNL2 SUMOylation in Arabidopsis has not yet been determined. In this study, we demonstrated that the C-terminal region of αKNL2 (designated αKNL2-C) interacts with small ubiquitin-like modifier 3 (SUMO3) and ULP1d, as shown by bimolecular fluorescence complementation and co-immunoprecipitation assays. Bioinformatic and functional analyses of αKNL2-C identified three SUMOylation sites and two SUMO-interacting motifs, which were shown to be critical for growth, fertility, and chromosome alignment. Of the three SUMOylation sites, Lys474 and Lys511 are the most critical for the centromeric localization of αKNL2, underscoring the importance of αKNL2 SUMOylation for its function. Additionally, both in vitro and in vivo assays showed that αKNL2-C undergoes SUMOylation by SUMO1 or SUMO3. The Arabidopsis SUMO protease mutant ulp1d-2 exhibits a mild accumulation of SUMOylated αKNL2. We further showed that SUMOylation of αKNL2 promotes its binding to CENH3 and controls protein stability. Our findings demonstrate that C-terminal SUMOylation of αKNL2 is crucial for its centromeric localization, interaction with CENH3, and kinetochore assembly, emphasizing the significance of post-translational modifications in chromosome segregation and cell division in plants.

Meiosis produces haploid gametes that are essential for sexual reproduction in most eukaryotes, but the specific cell-cycle regulation that controls meiotic progression in plants remains to be fully characterized. KNUCKLES (KNU), a known transcriptional repressor in floral meristem regulation, also regulates anther development. Loss of KNU function leads to male sterility in Arabidopsis, but its detailed regulatory mechanism is unknown. Here, we find that KNU is specifically localized in meiocytes during anther development, and mutation of KNU disrupts meiotic progression and behavior, leading to apoptosis of microsporocytes. Transcriptome analysis shows that numerous genes related to meiosis are downregulated in knu-2 meiocytes. We demonstrate that KNU can directly repress the expression of two cell-cycle inhibitors, INTERACTOR/INHIBITOR OF CDK 1/KIP-RELATED PROTEIN 1 (ICK1/KRP1) and KRP3, and knockout of KRP1 or KRP3 in the null allele knu-2 background largely rescues the knu-2 defects in male meiosis and fertility. Consistent with these results, overexpression of KRP1 driven by the native KNU promoter results in meiotic defects and reduced expression of some meiosis-related genes, similar to the phenotypes of knu-2. Thus, our findings provide evidence that the transcription factor KNU regulates the expression of meiotic cell-cycle regulators and cohesins through suppression of KRP1/3, significantly broadening our understanding of plant meiosis.

Triacylglycerol (TAG) degradation plays an important role in seed oil accumulation, but how this catabolic process is transcriptionally regulated in developing seeds remains poorly understood. Here, we identify a MYB-like helix-turn-helix (HTH) transcriptional regulator, PHR1-like 7 (PHL7), that enhances TAG degradation and decreases seed oil accumulation in Arabidopsis thaliana. PHL7 knockout (KO) plants (phl7) exhibited an approximately 10% increase in seed oil content, whereas PHL7 overexpression (OE) decreased oil content by 8%-13%. Compared with wild-type plants, phl7 displayed reduced expression of TAG degradation genes, including SUGAR-DEPENDENT 1 (SDP1), whereas OE lines exhibited elevated expression. Chromatin immunoprecipitation, electrophoretic mobility shift assays, and transactivation assays demonstrated that PHL7 binds the SDP1 promoter and activates its expression. We further found that PHL7 binds phosphatidic acid (PA), a key intermediate in TAG biosynthesis, and that PA suppresses PHL7 binding to the SDP1 promoter. The lysine residue at position 61 (K61) is required for PA interaction, and introducing the PHL7_K61S mutation into phl7 failed to restore seed oil content to wild-type levels. Together, these findings indicate that PHL7 promotes SDP1 expression, whereas PA attenuates this activity, revealing a lipid-mediated mechanism that balances TAG degradation and seed oil accumulation.

Cyperus rotundus, a globally distributed and highly competitive weed, has evolved herbicide resistance, posing a significant challenge to sustainable agriculture; however, the lack of genomic resources has limited comprehensive investigations into its resistance mechanisms. Here, we report a chromosome-level genome assembly of triploid C. rotundus (875.13 Mb across 165 chromosomes), which exhibits high synteny among haplotypes. Comparative analysis of six populations revealed that only a population from Changde, Hunan, China (designated R-HN) displayed dual resistance to glyphosate and glufosinate. In this population, high expression of the target-site resistance gene glutamine synthetase 2 (GS2) contributes to glufosinate resistance, whereas glyphosate resistance is predominantly mediated by non-target-site resistance (NTSR) mechanisms. By integrating transcriptomic profiling with yeast-based functional validation, we identified two NTSR genes, CrABCG15 and CrCASPL2C2, that confer glyphosate resistance. Collectively, this study provides a high-quality genomic resource for C. rotundus and advances our understanding of its genomic evolution and herbicide resistance mechanisms.

SUMO PROTEASE RELATED TO FERTILITY 1 (SPF1) and SPF2 are responsible for deSUMOylation of SUMO-conjugated protein substrates and for maintaining protein SUMOylation homeostasis. To date, the role of SUMO proteases in fatty acid biosynthesis and lipid accumulation remains unclear. Here, we demonstrate that the Arabidopsis thaliana mutantsspf1-1, spf2-1, and spf1-1 spf2-1 exhibit increased seed size and elevated seed oil content (SOC). We further show that SPF1 and SPF2 interact with WRINKLED1 (WRI1), a master regulator of the transcriptional control of plant oil synthesis. Genetic analyses indicate that the spf1-1 wri1-3 and spf2-1 wri1-3 double mutants, as well as the spf1-1 spf2-1 wri1-3 triple mutant, phenocopy wri1-3 and display severe seed shriveling, indicating that SPF1 and SPF2 act upstream of WRI1. WRI1 was identified as a SUMO1 substrate with two conserved SUMOylation sites, lysine 257 (K257) and K266, in cruciferous plants, with K257 acting as the dominant site required for seed oil synthesis. SUMOylation enhances WRI1 stability, whereas SPF1- and SPF2-mediated deSUMOylation promotes WRI1 degradation. In spf1-1, spf2-1, and spf1-1 spf2-1 mutants, the abundance of SUMOylated WRI1 increases during seed development and correlates with elevated seed oil accumulation. Together, these results indicate that SPF1 and SPF2 negatively regulate oil synthesis by deSUMOylating WRI1, establishing a dynamic SUMOylation and deSUMOylation switch centered on the SPF1/SPF2-WRI1 module that fine-tunes seed development and oil synthesis.

Ultraviolet-B (UV-B) radiation, a pervasive light stimulus, profoundly influences plant hypocotyl growth through intricate signaling pathways. Although the core UV-B signaling components have been identified, the precise regulatory mechanisms remain elusive. Here, we identify prefoldin 3 (PFD3), an α subunit of the PFD complex, as a novel negative regulator of UV-B-induced hypocotyl growth inhibition in Arabidopsis thaliana. Upon UV-B exposure, PFD3 accumulates and promotes the turnover of WRKY DNA-BINDING PROTEIN 70 (WRKY70) and FAR-RED ELONGATED HYPOCOTYL 3 (FHY3), thereby attenuating their transcriptional activities toward ELONGATED HYPOCOTYL 5 (HY5)/PACLOBUTRAZOL RESISTANCE1 (PRE1) and CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1), respectively. These findings delineate two regulatory modules-PFD3-WRKY70-HY5/PRE1 and PFD3-FHY3-COP1-that fine-tune UV-B-mediated inhibition of hypocotyl elongation in a UV RESISTANCE LOCUS 8-dependent manner. Furthermore, we identify amino acid variations in FHY3 from the high-altitude Tibet-0 ecotype of A. thaliana that confer resistance to PFD3-mediated suppression. This genetic adaptation sustains COP1 activation and results in shortened hypocotyls under UV-B radiation in this alpine ecotype. Collectively, our results suggest that allelic variation within these modules enhances adaptation to high-intense UV-B habitats, highlighting the evolutionary significance of these regulatory networks in plant environmental acclimation.