Molecular Plant最新文献

Barley (Hordeum vulgare ssp. vulgare) is one of the oldest founder crops in early human civilization, and has been widely dispersed around the globe to supply human life through livestock feeding and brewing industries. It has been used in innovative research of cytogenetics, biochemistry, and genetics since the early half of the 20^th century, facilitated by its mode of reproduction through self-pollination, its true diploid status which has contributed to the accumulation of a plethora of germplasm and mutant resources. Coming to the era of molecular genomics and biology, a multitude of barley genes and their involved regulatory mechanisms have been uncovered and functionally validated, providing the paradigm for equivalent studies in other Triticeae crops. This review features the advancements over the past decade in barley research, mainly regarding genomics and genomics-assisted germplasm exploration, genetic dissection of developmental and adaptation associated traits, as well as the complex dynamics of yield and quality formation. For the coming decade, the perspective of integration of these innovations in barley research and breeding is promising. Barley is proposed as a reference in Triticeae crops for new gene discovery, functional validation and molecular mechanism dissection. The application of precise genome editing as well as genomic prediction and selection, further enhanced by artificial intelligence-enforced tools and applications, is expected to boost barley improvement, in order to efficiently meet the evolving global demands for this important crop.

Effective plant defense against pathogens relies on highly coordinated regulation of immune gene expression. Enhancers, as cis-regulatory elements, are indispensable determinants of dynamic gene regulation, but the molecular functions in plant immunity are not well understood. In this study, we identified a novel enhancer, CORE PATTERN-INDUCED ENHANCER 35 (CPIE35), which is rapidly activated upon pathogenic elicitation and negatively regulates antifungal resistance through modulating WRKY15 expression. During immune activation, CPIE35 activates the transcription of WRKY15 by forming chromatin loops with the promoter of WRKY15 in a WRKY18/40/60-, WRKY33-, and MYC2-dependent manner. WRKY15 directly binds to the promoters of PAD3 and GSTU4, suppressing their expression and leading to reduced camalexin synthesis and resistance. Interestingly, CPIE35 region is evolutionarily conserved among Brassicaceae plants, and the CPIE35-WRKY15 module exerts similar functions in Brassica napus to negatively regulate antifungal resistance. Our work reveals the "enhancer-promoter-transcription factor" regulatory mechanism in maintenance of immune homeostasis, highlighting the importance and conserved role of enhancers in fine-tuning immune gene expression in plants.

Hormone perception and signaling pathways have a fundamental regulatory function in the physiological processes of plants. Cytokinins, a class of plant hormones, regulate cell division and meristem maintenance. The cytokinin signaling pathway is well established in the model plant Arabidopsisthaliana. Several negative feedback mechanisms, tightly controlling cytokinin signaling output, have been described previously. In this study, we identified a new feedback mechanism executed through alternative splicing of the cytokinin receptor AHK4/CRE1. A novel splicing variant named CRE1^int7 results from seventh intron retention, introducing a premature termination codon in the transcript. We showed that CRE1^int7 is translated in planta into a truncated receptor lacking the C-terminal receiver domain essential for signal transduction. CRE1^int7 can bind cytokinin but cannot activate the downstream cascade. We present a novel negative feedback mechanism of the cytokinin signaling pathway, facilitated by a decoy receptor that can inactivate canonical cytokinin receptors via dimerization and compete with them for ligand binding. Ensuring proper plant growth and development requires precise control of the cytokinin signaling pathway at several levels. CRE1^int7 represents a so-far unknown mechanism for fine-tuning the cytokinin signaling pathway in Arabidopsis.

Hornworts are the only land plants that employ a pyrenoid to optimize Rubisco's CO₂ fixation, yet hornwort Rubisco remains poorly characterized. Here we assembled the hornwort Anthoceros agrestis Rubisco (AaRubisco) using the Arabidopsis thaliana SynBio expression system and observed the formation of stalled intermediates, prompting us to develop a new SynBio system with A. agrestis cognate chaperones. We successfully assembled AaRubisco and Rubisco from three other hornwort species. Unlike A. thaliana Rubisco, AaRubisco assembly is not dependent on RbcX or Raf2. Kinetic characterization reveals that hornwort Rubiscos exhibit a range of catalytic rates (3-10 s^-1), but with similar affinity (∼30 μM) and specificity (∼70) for CO₂. These results suggest that hornwort Rubiscos do not comply with the long-held canonical catalytic trade-off observed in other land plants, providing experimental support that Rubisco kinetics may be phylogenetically constrained. Unexpectedly, we observed a 50% increase in AaRubisco catalytic rates when RbcX was removed from our SynBio system, without any reduction in specificity. Structural biology, biochemistry, and proteomic analysis suggest that subtle differences in Rubisco large-subunit interactions, when RbcX is absent during biogenesis, increases the accessibility of active sites and catalytic turnover rate. Collectively, this study uncovered a previously unknown Rubisco kinetic parameter space and provides a SynBio chassis to expand the survey of other Rubisco kinetics. Our discoveries will contribute to developing new approaches for engineering Rubisco with superior kinetics.