Cloning and characterization of VIGG, a novel virus-induced grapevine protein, correlated with fruit quality

An acyl-CoA-binding protein from grape that is induced through ER stress confers morphological changes and disease resistance in Arabidopsis

We here report characterization of a grape (Vitis vinifera) acyl-CoA-binding protein (VvACBP). Expression of VvACBP was detected in grape leaves exposed to tunicamycin-induced endoplasmic reticulum (ER) stress as well as cold and heat shock treatments. In tendrils and peduncles, however, high-temperature treatment induced BiP (luminal binding protein) expression, a marker of ER stress in berry skin, but not VvACBP expression. We hypothesize that VvACBP may be sorted to the periphery of plant cells. Transgenic Arabidopsis plants, expressing VvACBP, exhibited slowed-down floral transition. The gene expression of proteins related to the photoperiodic pathway, CONSTANS, FLOWERING LOCUS T (FT), and SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 (SOC1), was down-regulated in transgenic seedlings. These results underscore the possibility that VvACBP may affect the regulation of floral transition in Arabidopsis by suppressing the photoperiodic pathway. The transgenic Arabidopsis plants also exhibited morphological changes such as thicker inflorescences and rosette leaves. In addition, the rosette leaves of the transgenic plants had higher anthocyanin, total phenol, and chlorophyll contents than those of the control plants. Finally, the transgenic plants showed disease resistance to Pseudomonas syringae and Colletotrichum higginsianum, suggesting that VvACBP may also enhance disease resistance in grapevine.

Environmental stresses induce misfolded protein aggregation in plant cells in a microtubule-dependent manner

Misfolded protein aggregation in mammalian cells is one of the cellular responses to environmental stresses. However, the aggregation of misfolded proteins in plant cells exposed to environmental stresses is still poorly understood. Here, we report the misfolded protein aggregation in plant cells in response to environmental stresses, including ultraviolet (UV) radiation, heat stress and cold stress. Treatment of grape and tobacco cultured cells with MG-132, a proteasome inhibitor, induced misfolded protein aggregation. All of the environmental stresses examined induced the endoplasmic reticulum (ER) stress response in the cells. The cells under ER stress showed aggregation of misfolded proteins. The misfolded protein aggregation was completely inhibited by treatment of the cells with trichostatin A or colchicine, suggesting that the misfolded proteins might be aggregated in plant cells in a microtubule-dependent manner. Detected aggregates were initially observed immediately after exposure to the environmental stresses (1 min after UV radiation, 5 min after heat stress exposure, and 15 min after cold stress exposure). Based on these findings, we hypothesize that environmental stresses induce misfolded protein aggregation in plant cells in a microtubule-dependent manner.

Pink-colored grape berry is the result of short insertion in intron of color regulatory gene

We report here that pink grape berries were obtained by a short insertion in the intron of the MybA1 gene, a gene that regulates grape berry color. Genetic variation was detected among the MybA1 genes from grapes cultivated worldwide. PCR analysis of the MybA1 gene demonstrated that the size of the MybA1 gene in the red allele differs among grapes. Oriental V. vinifera bearing pink berries has the longest MybA1 gene among grapes, whereas the shortest MybA1 gene was detected in occidental V. vinifera grapes. The nucleotide sequences of the MybA1 genes demonstrated that oriental V. vinifera has two additional gene fragments (44 bp and 111 bp) in the promoter region of the MybA1 gene in the red allele and another 33 bp fragment in the second intron of the MybA1 gene in the red allele. The short insertion in the intron decreased the transcription activity in the model system and retained MybA1 transcripts with unspliced intron in the total RNA. From the experiments using deletion mutants of the 33 bp short insertion, 16 bp of the 3′ end in the insertion is a key structure for a defect in splicing of MybA1 transcripts. Thus, a weakly colored grape berry might be a result of the short insertion in the intron of a color regulatory gene. This is new evidence concerning the molecular mechanism of the fate of grape berry color. These findings are expected to contribute to the further understanding of the color variation in grape berries, which is correlated with the evolutional events occurring in the MybA1 gene of grapes.