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In common bean (Phaseolus vulgaris L.), postharvest seed coat darkening is an undesirable trait that affects crop value. The increased accumulation of proanthocyanidins (PAs) in the seed coat results in darker seeds in many market classes of colored beans after harvest. The precursors of PAs are synthesized in the cytoplasm, and subsequently get glycosylated and then transported to the vacuoles where polymerization occurs. Thus, vacuolar transporters play an important role in the accumulation of PAs. Here, we report that common bean genome contains 59 multidrug and toxic compound extrusion genes (PvMATEs). Phylogenetic analysis of putative PvMATEs with functionally characterized MATEs from other plant species categorized them into substrate-specific clades. Our data demonstrate that a vacuolar transporter PvMATE8 is expressed at a higher level in the pinto bean cultivar CDC Pintium (regular darkening) compared to 1533-15 (slow darkening). PvMATE8 localizes in the vacuolar membrane and rescues the PA deficient (tt12) mutant phenotype in Arabidopsis thaliana. Analysis of PA monomers in transgenic seeds together with wild-type and mutants suggests a possible feedback regulation of PA biosynthesis and accumulation. Identification of PvMATE8 will help better understand the mechanism of PA accumulation in common bean.
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Zhang Z, Chen L, Yu J. 2023. Maize WRKY28 interacts with the DELLA protein D8 to affect skotomorphogenesis and participates in the regulation of shade avoidance and plant architecture. Journal of Experimental Botany74, 3122–3141.
To feed the global population sufficiently from a small number of edible crops grown on limited arable lands, dense planting is required. However, high-density planting often induces the shade avoidance response (SAR), which is a limiting factor for yield. Plants undergo vegetative and reproductive changes to adapt to the varying amount and quality of incident light. These complex processes are delicately managed through signal transduction and regulatory systems comprising, but not limited to, receptors and transporters, hormones and specialized metabolites, and transcription factors (TFs). Zhang et al. (2023) have identified such a key regulatory element of the maize (Zea mays) SAR, ZmWRKY28, and explored its light-depended pathway regulation. They introduced a potential new target for maize yield improvement.
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