Plant Cell最新文献

Jojoba (Simmondsia chinensis) is a desert shrub with an unusual capacity to store liquid wax esters (WEs) in its seeds instead of triacylglycerols (TAGs) like most oilseed crops. To examine the factors that are important for WE compartmentalization in jojoba, we reconstituted WE biosynthesis and packaging in the leaves of Nicotiana benthamiana. Using this system, we screened jojoba proteins for their ability to support lipid droplet (LD) formation. A specific LIPID DROPLET-ASSOCIATED PROTEIN (LDAP) isoform, ScLDAP1, was identified as a key factor in the efficient compartmentalization of WEs in plant cells. LDAP1 isoforms from other plants (e.g. Arabidopsis thaliana [AtLDAP1]) did not support WE partitioning from the endoplasmic reticulum into LDs, although both AtLDAP1 and ScLDAP1 were targeted specifically to LD monolayer surfaces. ScLDAP1-mediated selective, efficient WE partitioning was facilitated by an amphipathic α-helix near its C-terminus, and mutational analysis identified 1 amino acid residue within this helix that was both necessary and sufficient for proper WE packaging into cytoplasmic LDs. Taken together, our results provide a mechanistic link between the biosynthesis and storage of WEs in plant cells, and will inform future biotechnology strategies for the efficient packaging of various neutral lipid types as demonstrated here for WEs in transgenic seeds.

Microscopy is a fundamental approach for plant cell and developmental biology as well as an essential tool for mechanistic studies in plant research. However, setting up a new microscopy-based experiment can be challenging, especially for beginner users, when implementing new imaging workflows or when working in an imaging facility where staff may not have extensive experience with plant samples. The basic principles of optics, chemistry, imaging, and data handling are shared among all cell types. However, unique challenges are faced when imaging plant specimens due to their waxy cuticles, strong/broad spectrum autofluorescence, recalcitrant cell walls, and air spaces that impede fixation or live imaging, impacting sample preparation and image quality. As expert plant microscopists, we share our collective experience on best practices to improve the quality of published microscopy results and promote transparency, reproducibility, and data reuse for meta-analyses. We offer plant-specific advice and examples for microscope users at all stages of fluorescence microscopy workflows, from experimental design through sample preparation, image acquisition, processing, and analyses, to image display and methods reporting in manuscripts. We also present standards for methods reporting that will be valuable to all users and offer tools to improve reproducibility and data sharing.

Fungi secrete effector proteins, including extracellular redox enzymes, to inhibit host immunity. Redox enzymes have been hypothesized to inhibit host reactive oxygen species (ROS); however, how they suppress host immunity remains unknown. We characterized an extracellular ascorbate peroxidase (MoApx1) that is secreted into rice chloroplasts by the rice blast fungus Magnaporthe oryzae. MoApx1 displays multifunctional capabilities that significantly contribute to fungal virulence. Firstly, MoApx1 neutralizes host-derived H2O2 within the chloroplast through its peroxidase activity, thereby inhibiting chloroplast ROS (cROS)-mediated defense responses. Secondly, MoApx1 targets the photosystem I subunit OsPsaD, disrupting photosynthetic electron transport to further suppress cROS production. Most importantly, MoApx1 has evolved a fungal-specific starch-binding domain that binds host starch, inhibiting its degradation and disrupting the energy supply required for host resistance. Our findings underscore the importance of a novel multifaceted strategy, potentially widely employed by other fungal pathogens, in suppressing host immunity during host-microbe interactions.