Expression and function identification of senescence-associated genes under continuous drought treatment in grapevine (Vitis vinifera L.) leaves.

Natural leaf senescence is critical for plant fitness. Drought-induced premature leaf senescence affects grape yield and quality. However, reports on the regulatory mechanisms underlying premature leaf senescence under drought stress are limited. In this study, two-year-old potted 'Muscat Hamburg' grape plants were subjected to continuous natural drought treatment until mature leaves exhibited senescence symptoms. Physiological and biochemical indices related to drought stress and senescence were monitored. Transcriptome and transgenic Arabidopsis were used to perform expression analyses and functional identification of drought-induced senescence-associated genes. Twelve days of continuous drought stress was sufficient to cause various physiological disruptions and visible senescence symptoms in mature 'Muscat Hamburg' leaves. These disruptions included malondialdehyde and H2O2 accumulation, and decreased catalase activity and chlorophyll (Chl) levels. Transcriptome analysis revealed that most genes involved in photosynthesis and Chl synthesis were downregulated after 12 d of drought treatment. Three key Chl catabolic genes (SGR, NYC1, and PAO) were significantly upregulated. Overexpression of VvSGR in wild Arabidopsis further confirmed that SGR directly promoted early yellowing of cotyledons and leaves. In addition, drought treatment decreased expression of gibberellic acid signaling repressors (GAI and GAI1) and cytokinin signal components (AHK4, AHK2, RR22, RR9-1, RR9-2, RR6, and RR4) but significantly increased the expression of abscisic acid, jasmonic acid, and salicylic acid signaling components and responsive transcription factors (bZIP40/ABF2, WRKY54/75/70, ANAC019, and MYC2). Moreover, some NAC members (NAC0002, NAC019, and NAC048) may also be drought-induced senescence-associated genes. These results provide extensive information on candidate genes involved in drought-induced senescence in grape leaves. Supplementary Information: The online version contains supplementary material available at 10.1007/s12298-024-01465-2.

Abscisic Acid Induces DNA Methylation Alteration in Genes Related to Berry Ripening and Stress Response in Grape (Vitis vinifera L).

Abscisic acid (ABA) is a major regulator of nonclimacteric fruit ripening, with its processes involving epigenetic mechanisms. It remains unclear whether DNA methylation is associated with ABA-regulated ripening. In this study, we investigated the patterns of DNA methylation and gene expression following ABA treatment in grape berries by using whole-genome bisulfite sequencing and RNA-sequencing. ABA application changed global DNA methylation in grapes. The hyper-/hypo-differently methylated regions were enriched in defense-related metabolism, degreening processes, or ripening-related metabolic pathways. Many differentially expressed genes showed an alteration in DNA methylation after ABA treatment. Specifically, ten downregulated genes with hypermethylation in promoters were involved in the ripening process, ABA homeostasis/signaling, and stress response. Nine upregulated genes exhibiting hypo-methylation in promoters were related to the ripening process and stress response. These findings demonstrated ABA-induced DNA alteration of ripening related and stress-responsive genes during grape ripening, which provides new insights of the epigenetic regulation of ABA on fruit ripening.

Predictors of Very Poor Outcome After Mechanical Thrombectomy in Older Patients with Acute Ischemic Stroke.

BACKGROUND: Mechanical thrombectomy (MT) is an effective treatment for patients with acute ischemic stroke due to large vessel occlusion. However, some elderly patients with recanalization have a very poor outcome, including vegetative state and mortality. This study evaluated predictors of very poor outcome at 3 months in older patients with stroke undergoing MT treatment. METHODS: We retrospectively collected data from consecutive stroke patients ≥80 years old undergoing MT between April 2018 and January 2021. A very poor outcome was defined as a modified Rankin Scale (mRS) score of 5 or 6 at 3-month follow-up. Multiple logistic regression analysis was performed to identify the predictors of very poor outcome at 3 months. RESULTS: The study enrolled 62 patients with a median age of 85.5 years (interquartile range: 82.0-89.0). Of patients, 35 (56.5%) had a very poor outcome at 3-month follow-up. Multiple logistic regression analysis identified female sex (odds ratio = 3.592, 95% confidence interval 1.047-12.319, P = 0.042) and stroke-associated pneumonia (odds ratio = 6.103, 95% CI 1.541-24.174, P = 0.010) as independent predictors of very poor outcome. CONCLUSIONS: In elderly stroke patients undergoing MT treatment, female sex and stroke-associated pneumonia were independent predictors of very poor outcome at 3 months.