Plant Communications最新文献

Legumes engage in nitrogen-fixing symbiosis with rhizobia, in which host legumes supply dicarboxylates as a carbon source to rhizobia, while rhizobia reciprocate by providing ammonium to the host plants. Beyond this classical model, accumulating evidence suggests that amino acid exchange is also essential for legume-rhizobium symbiosis. However, it remains unclear whether amino acid transporters are present on the symbiosome membrane (SM) to mediate amino acid exchange during symbiotic nitrogen fixation (SNF). In this study, we identified three amino acid transporters in Medicago truncatula-MtCAT1a, MtCAT1b, and MtCAT1c-which belong to a clade of the plant Cationic Amino acid Transporter (CAT) family known to transport a wide range of amino acids. Notably, MtCAT1b and MtCAT1c are predominantly expressed in infected nodule cells and localize to the SM. Genetic analyses further demonstrate that both MtCAT1b and MtCAT1c are required for amino acid exchange at the SM, with additional evidence indicating that bacteroid metabolism is disturbed in the mutants. Transport assays show that both MtCAT1b and MtCAT1c exhibit broad substrate specificity. Collectively, these findings identify MtCAT1b and MtCAT1c as key mediators of cross-kingdom amino acid exchange, which is essential for maintaining efficient SNF in root nodules.

Mitochondrial biogenesis requires the import of more than a thousand proteins encoded by nuclear DNA. The translocase of the outer mitochondrial membrane (TOM) complex serves as the primary gateway for specific recognition of precursor proteins, which are synthesized in the cytosol. Little is known about the regulation of the abundance of the TOM complex. Using forward genetics, we identified key 26S proteasome subunits, including REGULATORY PARTICLE NON-ATPASE1A (RPN1A), that affect the abundance of TOM-complex subunits through the ubiquitin-proteasome pathway. Loss of proteasome function through rpn1a mutation or MG132 treatment increased the abundance of TOM20 isoforms and induced mitochondrial stress marker genes. By contrast, overexpression of ANAC017, an endoplasmic reticulum-anchored transcription factor that activates mitochondrial retrograde signaling under stress, lowered TOM20 abundance and reduced mitochondrial protein import. The rates of mitochondrial protein import and respiratory activity were also altered. Genetic analyses placed the proteasome downstream of ANAC017, since the reduction in TOM20 required the RPN1a subunit. Transcriptome profiling after antimycin A treatment showed broad ANAC017-dependent reprogramming of ubiquitin-proteasome system genes. A second tier formed by ANAC053- and ANAC078-bound promoters of proteasome subunits, including RPN1a, is required to restrain TOM20 accumulation. These findings establish a two-step transcriptional circuit that engages the ubiquitin-proteasome system to tune TOM abundance and coordinate protein import with organelle function.

Centromeres are essential for accurate chromosome segregation and genome stability; with the advent of telomere-to-telomere genome assemblies, they have become central targets of genome-wide studies. Here, we present CentriVision, a modular bioinformatics platform that integrates candidate centromere identification, structural similarity assessment, DNA repeat unit decomposition, and a framework for exploring potential relationships between single-nucleotide conservation and functional features. CentriVision provides a comprehensive suite of analytical tools, including edit-distance dot plots, intra-segment heatmaps, kilobase-scale mini-dot plots, repeat monomer scanning with conserved-site visualization, and satellite DNA expansion-divergence estimation, all of which can be seamlessly integrated with CENH3 chromatin immunoprecipitation sequencing (ChIP-seq) data. When applied to representative plant species, CentriVision achieved high predictive accuracy and revealed diverse organizational patterns. Arabidopsis thaliana centromeres are primarily composed of 178-188-bp repeats interspersed with rarer ∼502-bp variants that exhibit pronounced sequence conservation but only background CENH3-ChIP signal, suggesting that these elements represent pre-centromeric sequences overlooked in earlier studies. Oryza sativa contains two dominant classes of centromeric repeats rather than the single class previously reported. In contrast, Zea mays exhibits strongly biased expansion toward the evolution of a single dominant repeat unit, reflecting a distinct evolutionary strategy of centromere reconstruction, whereas Papaver setigerum displays a notable three-layered nested repeat structure. Integration of repeat sequence divergence with CENH3 binding further revealed lineage-specific evolutionary trajectories of centromere specification. Collectively, these findings advance our understanding of centromere structure and function. CentriVision offers a reproducible, scalable, and user-friendly framework that quantitatively links repeat evolution, structural variation, and functional epigenomics, providing new insights into the architecture and diversification of plant centromeres.

The global yield of cottonseed could meet the annual protein requirements of approximately half a billion people if gossypol were absent from the seeds. Here, we characterize the molecular mechanism by which the Gl₂^e mutation exerts a dominant-negative effect on gland development, providing a mechanistic basis for engineering seed-specific gossypol-free (SSGF) cotton. We show that Gl₂/Gl₃ form multimers-likely tetramers-that function as master regulators within the transcriptional network controlling gossypol gland development. Further analyses demonstrate that Gl₂^e, a dominant mutant allele of Gl₂, induces a glandless phenotype through its dominant-negative effect. In addition, multimers composed of Gl₂^e and Gl₂/Gl₃ retain E-box binding activity but lack transcriptional activation capacity, thereby inhibiting gland organogenesis. Guided by these insights, we engineered SSGF cotton by driving Gl₂^e expression specifically during seed development, effectively suppressing gossypol gland formation in seeds. Multi-year, multi-location field trials of the SSGF cotton confirmed the stable production of gossypol-free seeds without compromising fiber yield or other key agronomic traits. Notably, completely gossypol-free oil and flour can be produced directly from SSGF seeds without the need for degossypolization. This work establishes a mechanistic foundation for understanding gland development and offers a sustainable path toward enhancing global plant-derived protein and oil resources.

Brassinosteroids (BRs) are steroid-type phytohormones that are essential for plant growth, development, and adaptation to environmental stresses. BRs are known to control microtubule (MT) orientation, which is pivotal for directional growth, but the underlying molecular mechanisms are still largely unknown. Here, we identified and characterized a new family of BRI1-interacting proteins named MICROTUBULE-BRI1-ASSOCIATED PROTEINS (MBAPs). We confirmed, using several complementary approaches, that MBAPs are genuine BRI1 partners in plant cells. We demonstrated that MBAPs localize to cortical microtubules (CMTs) underlying the plasma membrane using a short conserved helix, where they make contact with BRI1. Combinations of mbap loss-of-function mutants showed hypersensitivity to BRs and established MBAPs as negative regulators of BR responses. mbap mutants showed no changes in typical downstream BR signaling readouts and selected BR-regulated genes, and they displayed only mild changes when global BR genomic responses were probed. Consistent with the localization of MBAPs to CMTs, mbap mutants displayed a disordered CMT network and enhanced CMT reorganization upon BR perception. Together, our results shed light on the role of MBAPs as a bridge between BR perception at the cell surface and CMT organization in the control of hypocotyl elongation.

Heterosis has significantly improved crop yields, yet hybrid seed production remains hindered by labor-intensive manual emasculation. Although current male-sterility systems, such as cytoplasmic male sterility and environment-sensitive genic male sterility, have improved the efficiency of hybrid seed production, their limited genetic adaptability and high environmental dependence remain major challenges. Here, we report an all-in-one seed production technology (ASPT) that integrates CRISPR-Cas9, RUBY, and key seed production technology (SPT) components into a single vector, enabling efficient generation and propagation of male-sterile lines in both maize and rice. The engineered RUBY marker enables visual identification of male-sterile and maintainer lines, with an accuracy of 99.81% in automated seed sorting and 100% in secondary field screening. Notably, ASPT was successfully introduced into 21 genetically diverse elite maize inbred lines, demonstrating broad compatibility. ASPT enables scalable and precise propagation of male-sterile lines in both maize and rice, providing a broadly applicable strategy to advance hybrid seed production in crops.

Rhizobial type-Ⅲ effectors (T3Es) contribute to establishing symbiotic interactions with legume host plants, alongside Nod factors. However, the functions of most rhizobial T3Es, as well as the regulatory and molecular mechanisms underlying their symbiotic effects on hosts, particularly in soybean, are poorly documented. Here, we characterize the function of the T3E Nodulation Outer Protein C (NopC) in the broad-host-range rhizobium Sinorhizobium fredii HH103 for promoting symbiosis in soybean. NopC genotype influences root nodulation across diverse host germplasm and this is further influenced by GmRAC1, encoding a ROP/RAC family GTPase in soybean. GmRAC1 physically interacts with NopC to subsequently induce the expression of the essential symbiotic genes GmNIN2a/2b and GmENOD40. Knock-down of GmNIN2a/2b results in NopC failing to promote symbiosis, and Gmrac1 mutants have fewer nodules than the wild type. NopC facilitates multiple infection stages whereas the requirement for GmRAC1 is pronounced for infection-thread progression and nodule-primordia initiation. Natural variation in the GmRAC1 promoter largely dictates the symbiotic contribution of NopC during symbiotic establishment, and elite GmRAC1 haplotypes with strong expression were artificially selected in soybean breeding. Transgenic over-expression level and elite GmRAC1 haplotypes increase plant height, 100-seed weight and soybean yield. GmRAC1 serves as a key regulator of NopC-mediated symbiosis promotion and offers translational potential for enhanced symbiotic nitrogen fixation in molecular breeding of soybean.