A plant-unique protein BLISTER coordinates with core retromer to modulate endosomal sorting of plasma membrane and vacuolar proteins.

The retromer is a heteromeric protein complex that localizes to endosomal membranes and drives the formation of endosomal tubules that recycle membrane protein cargoes. In plants, the retromer plays essential and canonical functions in regulating the transport of vacuolar storage proteins and the recycle of endocytosed plasma membrane proteins (PM); however, the mechanisms underlying the regulation of assembly, protein stability, and membrane recruitment of the plant retromer complex remain to be elucidated. In this study, we identify a plant-unique endosomal regulator termed BLISTER (BLI), which colocalizes and associates with the retromer complex by interacting with the retromer core subunits VPS35 and VPS29. Depletion of BLI perturbs the assembly and membrane recruitment of the retromer core VPS26-VPS35-VPS29 trimer. Consequently, depletion of BLI disrupts retromer-regulated endosomal trafficking function, including transport of soluble vacuolar proteins and recycling of endocytosed PIN-FORMED (PIN) proteins from the endosomes back to the PM. Moreover, genetic analysis in Arabidopsis thaliana mutants reveals BLI and core retromer interact genetically in the regulation of endosomal trafficking. Taken together, we identified BLI as a plant-specific endosomal regulator, which functions in retromer pathway to modulate the recycling of endocytosed PM proteins and the trafficking of soluble vacuolar cargoes.

NAA at a high concentration promotes efficient plant regeneration via direct somatic embryogenesis and SE-mediated transformation system in Ranunculus sceleratus.

The novel methods for efficient plant regeneration via direct somatic embryogenesis (SE) and SE-mediated transformation system under high concentration of NAA in Ranunculus sceleratus were established. On MS media containing a high concentration of NAA (10.0 mg/L) in the dark, all inoculated explants (root, stem and leaf) formed somatic embryos at high frequencies, respectively, 66.03, 126.47 and 213.63 embryoids per explant, and 100% of the embryoids developed into plantlets on 1/2 MS rooting media. Morphological and histological analyses revealed that SE in R. sceleratus followed a classical pattern. All inoculated explants can be used as receptors for genetic transformation in R. sceleratus, through direct SE-mediated method after Agrobacterium infection. RcLEC1-B, as a marker gene, changed the number and morphology of flower organs and the development of cuticle in R. sceleratus, which indicated that the efficient transgenic system of R. sceleratus was established. To our knowledge, this is the first observation that both direct SE and transgenic transformation system, via induction of a single plant growth regulator, have been successfully constructed in R. sceleratus.

Overexpression of RcLEC1-B, a HAP3 transcription factor of PLB from Rosa canina, increases the level of endogenous gibberellin and alters the development of cuticle and floral organs in Arabidopsis.

The HAP3 subfamily gene RcLEC1-B, was isolated from protocorm-like body (PLB) of Rosa canina, encodes 213 amino acid residues. It was shown that RcLEC1-B was specifically expressed in PLB of R. canina and its subcellular localization is in the nucleus. Overexpression of RcLEC1-B in Arabidopsis resulted in a decrease in endogenous ABA level, an increase in GA, IAA and CTK contents, and an increased number of branches. RcLEC1-B promotes the formation of spontaneous embryoids, suggesting that it may be a homolog of the Arabidopsis LEC1 gene. RcLEC1-B-OE changed the number and morphology of flower organs and resulted in open carpels and exposed ovules, along with a reduced percentage of fertile fruit. This is the first observation that overexpression of a homolog of LEC1 in Arabidopsis can lead to morphological changes in floral organs, cuticle defects, and adhesions between organs; this may result from the increased level of gibberellin in the transgenic plants.