Plant Physiology最新文献

The genetically tractable unicellular red alga Cyanidioschyzon merolae has a remarkably simple genome (4,775 nucleus-encoded proteins) and cellular architecture. It contains only a single set of most membranous organelles, making it a valuable tool for elucidating the fundamental mechanisms of photosynthetic eukaryotes. However, as in other genetically tractable eukaryotic algae, previously developed systems for inducible gene expression rely on environmental stimuli such as heat shock or ammonium depletion, which impact cellular physiology and thus limit their usage. To overcome this issue, we developed IPTG- and estradiol-inducible gene expression systems in C. merolae in which the addition of these chemicals itself has no impact on cellular growth or the transcriptome. Additionally, we established IPTG- and estradiol-inducible protein knockdown systems and successfully degraded the endogenous chloroplast division protein DRP5B using the estradiol-inducible system. These systems facilitate functional genomic analyses in C. merolae, especially for understanding physiological mechanisms and their interactions in photosynthetic eukaryotes.

Rice (Oryza sativa) indica and japonica inter-subspecific hybrids hold significant potential for increasing yields. However, differences in diurnal flower-opening time (DFOT) between the two subspecies limit the effective exploitation of this heterosis. Additionally, the timing of post-anthesis glume closure (PAGC) affects both hybrid seed yield and quality. Despite their importance, the molecular mechanisms underlying these processes, particularly glume closure, remain poorly understood. In this study, we identify OsAIM1 as a pivotal regulator of both DFOT and PAGC in rice. The aim1-2 mutant exhibits delayed DFOT and impaired PAGC while maintaining normal floret structure, emphasizing its crucial role in floret dynamics. OsAIM1 is highly expressed in lodicules and encodes a peroxisome-localized multifunctional protein. Functional analyses reveal that OsAIM1 regulates lodicule swelling during floret opening and withering post-anthesis, processes essential for glume movement. We further demonstrate that OsAIM1-dependent jasmonic acid (JA) biosynthesis is indispensable for coordinating floret opening and closure and influences sugar transport to ensure proper lodicule dynamics. Importantly, natural variation in the OsAIM1 coding region contributes to DFOT divergence between japonica and indica subspecies, providing a molecular basis for their asynchronous flowering. These findings establish OsAIM1 as a key regulator of floret dynamics and a promising molecular target for synchronizing flowering in hybrid rice production.

Sporopollenin, a structurally complex and chemically recalcitrant biopolymer, forms the outer exine layer of plant spores and pollen, protecting male gametes from environmental stresses. Varying levels of phenolic constituents are incorporated as building blocks into sporopollenin in many species, but how this process evolved remains unclear. Using an optimized alkaline hydrolysis method, along with NMR spectroscopy and GC-MS, we determined that plants have evolved the ability to incorporate phenolic compounds into sporopollenin in a phylogenetically ordered manner. Covalently linked phenolic constituents, including p-coumarate (p-CA), ferulate, p-hydroxybenzoate, naringenin, the canonical monolignol p-hydroxyphenyl unit and guaiacyl unit, occur in sporopollenin of vascular but not non-vascular plants. Evolutionary analyses showed that the metabolic scaffold for phenolic precursors evolved before the integration of phenolics into sporopollenin in vascular plants. The conserved multicopper oxidase SCULP1, which incorporates p-CA into sporopollenin, co-occurred with p-coumaroylation of sporopollenin in vascular plants, likely contributing to the prevalence of p-coumaroylated sporopollenin. These findings provide an evolutionary framework for understanding genetic associations with sporopollenin chemical diversification and plant adaptation.

In plants, both developmental processes and environmental responses are spatiotemporally regulated by an assembly of signaling molecules such as hormones, secondary metabolites, and ions. The ability of these signaling molecules to move within and across plant tissues is essential for various developmental cues. However, the characterization of transported signaling molecules and their translocation mechanisms is difficult due to the functional redundancy of plant genomes and shortcomings in methodologies. Here, we report our development of the Multi Targeted AmiRNA Cell type-specific Transportome-scale (mTACT) toolbox, which can be used to reveal phenotypic plasticity in plants. mTACT is based on a large set of artificial microRNAs (amiRNAs), each designed to optimally target multiple members of a particular gene family encoding transporter proteins. In total, the mTACT toolbox includes 5,565 amiRNAs, targeting 81.7% of the Arabidopsis (Arabidopsis thaliana) transportome. The amiRNA library can be driven under 12 cell type-specific promoters, allowing the design of spatial-specific genetic screens. mTACT is further divided into eight sub-libraries of amiRNAs targeting a functionally defined protein class. A proof-of-concept screen validated the mTACT approach by identifying phenotypes linked to both known and unidentified genes. With the ability to overcome functional redundancy in a transportome-scale, cell type-specific manner, the mTACT toolbox will allow the plant research community to study previously hidden genetic factors required for long- and short-distance translocation of signaling molecules.