Hardy kiwifruit (Actinidia arguta) is a promising fruit species in the family Actinidiaceae with increasing commercial production worldwide (Latocha et al. 2014). During April and May of 2015, with high humidity and cool temperature conditions, typical symptoms of Sclerotinia rot with about 10% incidence were observed on 2-year-old seedlings in Zuojia Town, Jilin Province, China. Symptoms started as black-brown watery soft rot, quickly expanded and girdled on the basal stems, at the same time the leaves became yellow and wilted. Finally, the plants wilted and died. White mycelium and occasionally irregular black sclerotia (1.2 to 4.5 mm in diameter) were also observed on the rotted basal stem and roots of plants. Sclerotia were collected from symptomatic tissue, surface-disinfested with 70% ethanol for 30 sec and 0.1% HgCl2 for 1 min, triple rinsed with sterile water, and plated on potato dextrose agar (PDA), and incubated 4 to 5 days at 20 °C. Within 2 to 4 days, white mycelia were pulled from the sclero...

Vitis amurensis is a cold-hardy wild grape species and represents valuable germplasm for breeding cold-tolerant grapevines. In this study, we identified a highly expressed gene (VaTPS9) in one-year-old shoots of V. amurensis ‘Shuangfeng’ during overwintering, but its biological function remained unclear. Temporal and spatial expression analyses revealed distinct expression patterns of VaTPS9 among different tissues from June to November, with the highest transcript abundance detected in one-year-old shoots in November. Gene cloning and sequence alignment showed that VaTPS9 encoded a type II trehalose-6-phosphate synthase (TPS) and was designated as VaTPS9. Functional analyses demonstrated that overexpression of VaTPS9 enhanced cold tolerance in yeast, Arabidopsis thaliana, and V. amurensis callus tissues. Conversely, virus-induced gene silencing (VIGS) of VaTPS9 in grapevine plantlets markedly increased cold sensitivity under low-temperature stress. These reciprocal gain- and loss-of-function phenotypes indicate that VaTPS9 positively regulates cold tolerance, likely by modulating trehalose metabolism and associated physiological responses, including reactive oxygen species (ROS) homeostasis. Collectively, our findings provide new insights into the molecular basis of cold adaptation in wild grape species and highlight VaTPS9 as a promising candidate gene for improving cold tolerance in cultivated grapevine.

Actinidia arguta is a dioecious plant, and the selection of superior male germplasm is crucial for ensuring effective pollination of female cultivars, maximizing their economic traits, and achieving high-quality yields. This study evaluated 30 male germplasms for pollen quantity, germination capacity, storage characteristics, and ultrastructural features. Results revealed significant variation in pollen germination rates (1.56–96.57%) among germplasms, with ‘Lvwang’, ‘TL20083’, and ‘TG06023’ performing best (all >90% germination). The storage characteristics study demonstrated that −80 °C is the optimal temperature for long-term pollen storage in A. arguta. Significant variations were observed in storage tolerance among different germplasms. Among them, Lvwang exhibited the best performance, maintaining a germination rate of 97.40% after 12 months of storage at −80 °C with no significant difference from the initial value, followed by TT07063. Pollen morphology was closely correlated with fertility. High-fertility pollen grains typically exhibited standard prolate or ultra-prolate shapes, featuring a tri-lobed polar view and an elliptical equatorial view, with neat germination furrows and clean surfaces. In contrast, low-fertility pollen grains frequently appeared shrunken and deformed, with widened germination furrows and visible exudates. Based on these findings, the following recommendations are proposed: ① Prioritize the use of germplasms with pollen germination rates >80% as pollinizers; ② Establish a rapid screening system based on pollen morphological characteristics. This study provides important scientific basis for both male germplasm selection and efficient cultivation practices in A. arguta (kiwiberry).