Plant Communications最新文献

As an important yield component, the rice tiller number controls panicle number and determines grain yield. The regulation of rice tiller number by chloroplast pentatricopeptide repeat (PPR) proteins has not been reported. Here, we report a rice reduced culm number22 (rcn22) mutant which produces few tillers due to suppressed tiller bud elongation. Map-based cloning revealed that RCN22 encodes a chloroplast-localized P-type PPR protein. We found that RCN22 specifically binds to the 5'-UTR of RbcL mRNA (encoding the large subunit of Rubisco) and enhances its stability. The reduced RbcL mRNA abundance in rcn22 led to a lower photosynthetic rate and decreased sugar levels. Consequently, transcript levels of DWARF3 (D3) and TEOSINTE BRANCHED1 (TB1) (encoding negative regulators of tiller bud elongation) increased, whereas protein levels of a positive regulator DWARF53 (D53) decreased. Furthermore, high concentrations of sucrose could rescue the tiller bud growth defect of the rcn22 mutant. On the other hand, TB1 directly binds to the RCN22 promoter and downregulates its expression. The tb1/rcn22 double mutant showed a tillering phenotype similar to rcn22. Our results suggest that the TB1-RCN22-RbcL module plays a vital role in rice tiller bud elongation by affecting sugar levels.

Plants utilize plasma membrane-localized pattern recognition receptors (PRRs) to perceive pathogen-associated molecular patterns (PAMPs) to activate broad-spectrum pattern-triggered immunity (PTI). However, the regulatory mechanism ensuring robust broad-spectrum plant immunity remains largely unknown. Here, we reveal the dual roles of the transcription factor WRKY8 in transcriptional regulation of PRR genes: repressing the nlp20/nlp24 receptor gene RLP23 whereas promoting the chitin receptor gene CERK1. Remarkably, SsNLP1 and SsNLP2, two nlp24 type PAMPs in the destructive fungal pathogen Sclerotinia sclerotiorum, activate two calcium-elicited kinases, CPK4 and CPK11 to phosphorylate WRKY8 and consequently release its inhibition on RLP23 expression to accumulate RLP23. Meanwhile, SsNLPs activate a RLCK type kinase, PBL19 to phosphorylate WRKY8 and consequently enhance the accumulation of CERK1. Intriguingly, RLP23 is repressed at late stage by PBL19-mediated phosphorylation of WRKY8, to avoid excessive immunity for normal growth. Our findings unveil a "killing two birds with one stone" strategy employed by plants to elicit robust broad-spectrum immunity, which is based on PAMP-triggered fine-tuning of a dual-role transcription factor to simultaneously amplify two PRRs recognizing PAMPs well conserved in a wide range of pathogens. Moreover, our results reveal a novel plant strategy based on fine-tuning of multiple PRR gene expression to balance the trade-off between growth and immunity.

Plastid biogenesis and the coordination of plastid and nuclear genome expression through anterograde and retrograde signaling are essential for plant development. GENOMES UNCOUPLED1 (GUN1) plays a central role in retrograde signaling during early plant development. The putative function of GUN1 has been extensively studied, but its molecular function remains controversial. Here, we evaluate published transcriptome data and generate our own data from gun1 mutants grown under signaling relevant conditions to show that editing and splicing are not relevant for GUN1-dependent retrograde signaling. Our study of the plastid (post)-transcriptome of gun1 seedlings with white and pale cotyledons demonstrates that GUN1 deficiency significantly alters the entire plastid transcriptome. By combining this result with a PPR code-based prediction and experimental validation by RNA immunoprecipitation experiments, several putative targets of GUN1 were identified, including tRNAs and RNAs derived from ycf1.2, rpoC1 and rpoC2, and the ndhH-ndhA-ndhI-ndhG-ndhE-psaC-ndhD gene cluster. The absence of plastid rRNAs and the significant reduction of almost all plastid transcripts in white gun1 mutants account for the cotyledon phenotype. Our study provides evidence for RNA binding and maturation as the long-sought molecular function of GUN1 and resolves long-standing controversies. We anticipate that our findings will serve as a basis for subsequent studies investigating the mechanism of plastid gene expression and will facilitate the elucidation of GUN1's function in retrograde signaling.

This study leveraged knowledge of the specific known cultivar progenitor "Nanjing11" of a weedy rice population from East China, and discovered that the landrace introgression greatly contributed to the recent feralization of modern cultivars, including the introduction of the Rc gene that confers key weedy traits such as red pericarp and seed dormancy.

Carotenoid biosynthesis is closely associated with abscisic acid (ABA) during the ripening process of non-climacteric fruits, but the regulatory mechanism between ABA signaling and carotenoid metabolism remains largely unclear. Here, we identified two master regulators of ABA-mediated citrus fruit coloration, CsERF110 and CsERF53, which activated the expression of carotenoid metabolism genes (CsGGPPS, CsPSY, CsPDS, CsCRTISO, CsLCYB2, CsLCYE, CsHYD, CsZEP, and CsNCED2) to facilitate carotenoid accumulation. Further investigations showed that CsERF110 not only activated the expression of CsERF53 by binding to its promoter, but also interacted with CsERF53 to form a transcriptional regulatory module CsERF110-CsERF53. Furthermore, we discovered a positive feedback regulation loop between the ABA signal and carotenoid metabolism regulated by the transcriptional regulatory module CsERF110-CsERF53. Our results reveal that the transcriptional regulatory module CsERF110-CsERF53 responded to ABA signaling, thereby orchestrating citrus fruit coloration. Considering the importance of carotenoid content for citrus and many other carotenoid-rich crops, the revelation of molecular mechanisms underlying ABA-mediated carotenoid biosynthesis in plants will facilitate transgenic/gene editing approach development, further contributing to improving the quality of citrus and other carotenoid-rich crops.

The transcriptome serves as a bridge that links genomic variation and phenotype diversity. A vast number of studies using next-generation RNA sequencing (RNA-seq) in the last two decades emphasize the essential roles of plant transcriptome in response to developmental and environmental conditions, leading to numerous insights into the dynamic change, evolutionary trace and elaborate regulation of plant transcriptome. With substantial improvement in accuracy and throughput, direct RNA sequencing (DRS) has emerged as a new and powerful sequencing platform for the precise detection of native and full-length transcripts, which overcomes many limitations such as read length and PCR bias that are inherent to short-read RNA-seq. Here, we reviewed recent advances in dissecting the complexity and diversity of plant transcriptome utilizing DRS as a main technological mean from many aspects of RNA metabolism, including novel isoforms, poly(A) tail and RNA modification, and proposed a comprehensive workflow for the data process of plants DRS. Many challenges concerning the application of DRS in plants, such as machine learning tools tailored to plant transcriptome, remain to be solved, and together we prospect the future biological questions that can be potentially answered by DRS such as allele-specific RNA modification. This technology provides convenient support on which the connection of distinct RNA features is tightly built, sustainably refining our understanding of the biological functions of plant transcriptome.