Plant Physiology最新文献

Extracellular vesicles (EVs) produced by Arabidopsis (Arabidopsis thaliana) plants are highly heterogeneous in protein content. To understand the origins of plant EV heterogeneity, we used an unbiased proximity labeling approach to identify proteins and pathways involved in the secretion of distinct EV subpopulations. Proximity labeling, co-immunoprecipitation, and fluorescence microscopy in Nicotiana benthamiana all indicated a general role in EV secretion for EXO70 proteins (a subunit of the exocyst complex) and the immune-related protein RPM1-INTERACTING PROTEIN4 (RIN4). To confirm these hypotheses, we assessed the impact of mutations in various EXO70 family genes and in RIN4 on EV release, as well as mutations in additional genes known to regulate endomembrane trafficking and secretion. Mutation of EXO70E1, EXO70E2 or STOMATAL CYTOKINESIS DEFECTIVE1 (SCD1; a GTP-exchange factor for RabE GTPases) reduced secretion of EVs marked by TETRASPANIN8 (TET8), PENETRATION1 (PEN1), and PATELLIN1 (PATL1), indicating that these proteins are generally required for EV secretion. In contrast, mutation of RIN4 reduced levels of TET8+ and PEN1+ EVs, but not PATL+ EVs. Mutation of the small GTPase gene RABA2a specifically affected PEN1+ EV secretion, while mutations in AUTOPHAGY PROTEIN5 (ATG5) and VAMP-ASSOCIATED PROTEIN27 (VAP27) specifically affected TET8+ EV secretion. Lastly, we found that exo70 family mutants are more susceptible to infection with the fungal pathogen Colletotrichum higginsianum, underlining the importance of secretion for plant immunity. Together, our results unravel some of the complex mechanisms that give rise to EV subpopulations in plants.

Plants possess conserved immune systems to defend against herbivorous insects. In response, insects secrete saliva to manipulate host cell biology, with many salivary proteins being species-specific. The mechanisms by which different insects, armed with distinct salivary components, counteract the conserved plant immune systems are not well understood. Here, we describe how two salivary effectors from the brown planthopper Nilaparvata lugens and the bean bug Riptortus pedestris target pathogenesis-related germin-like proteins (GLPs) in rice and soybean. In N. lugens, NlGTSP is expressed exclusively in the salivary glands and is secreted into host plants during feeding. Its knockdown significantly reduces phloem feeding and reproduction, whereas overexpression in rice enhances insect performance and rescues NlGTSP deficiency. NlGTSP partly modulates defenses by interacting with plant GLPs and inhibiting their enzymatic activity. In R. pedestris, the salivary protein RpGDSP lacks sequence or structural similarity to NlGTSP but also targets GLPs, promoting their degradation via the ubiquitin pathway to enhance feeding. Collectively, our findings reveal a functional analogy between salivary effectors from different insects that regulate core plant defense genes through distinct mechanisms.

Light and subterranean darkness play a crucial role in early plant development which guide seamless progression from a dormant seed to a well-established seedling. In seed plants crosstalk between light and hormone signaling pathways optimizes seed germination. This is followed by etiolated growth characterized by the formation of a long hypocotyl and closed cotyledons forming apical hook. These etiolated structures facilitate the efficient emergence of seedlings from underneath the soil. Upon emergence, exposure to light promotes the de-etiolation process, characterized by inhibition of hypocotyl elongation and formation of open and green cotyledons. The early developmental steps in a plant's life-cycle which include seed germination and post-germinative seedling establishment, are the most stress sensitive stages. To acclimatize with the changing environment plants must activate stress resilience pathways. Recent studies shed light on how light and dark regulated factors modulate responses to combat various abiotic stresses including high temperature, high-intensity light, UV-B radiation and salinity stress. Plant biologists have traditionally examined plant-environment interactions utilizing two complementary but distinct approaches. Developmental biology has focused on the interplay of external influences such as light, temperature and endogenous cues like phytohormones to modulate plant development. Stress biology, in contrast, has studied how various physiological and molecular processes are regulated in response to environmental stress and leading to the plant's ability to adapt. Here we link these two concepts by demonstrating how light-controlled developmental-programs are tightly connected to stress-responsive pathways. These interconnected systems provide flexibility and resilience to plants to survive and evolve under dynamic environments.