Genome-wide identification of GH9 gene family and the assessment of its role during fruit abscission zone formation in Vaccinium ashei

Abstract

Glycosyl hydrolase family 9 (GH9) cellulases play a crucial role in both cellulose synthesis and hydrolysis during plant growth and development. Despite this importance, there is currently no study on the involvement of GH9-encoding genes, speci cally VaGH9s, in abscission zone formation of rabbiteye blueberries (Vaccinium ashei). In this study, we identi ed a total of 61 VaGH9s in the genome, which can be classi ed into three subclasses based on conserved motifs and domains, gene structures, and phylogenetic analyses. Our synteny analysis revealed that VaGH9s are more closely related to the GH9s of Populus L. than to those of Arabidopsis, Vitis vinifera, and Citrus sinensis. In-silico structural analysis predicted that most of VaGH9s are hydrophilic, and localized in cell membrane and/or cell wall, and the variable sets of cis-acting regulatory elements and functional diversity with four categories of stress response, hormone regulation, growth and development, and transcription factor-related elements are present in the promoter sequence of VaGH9s genes. Transcriptomic analysis showed that there were 22 differentially expressed VaGH9s in fruit abscission zone tissue at the veraison stage, and the expression of VaGH9B2 and VaGH9C10 was continuously increased during fruit maturation, which were in parallel with the increasing levels of cellulase activity and oxidative stress indicators, suggesting that they are involved in the separation stage of fruit abscission in Vaccinium ashei. Our work identi ed 22 VaGH9s potentially involved in different stages of fruit abscission and would aid further investigation into the molecular regulation of abscission in rabbiteye blueberries fruit. Key messageThe genomic location and stage-speci c expression pattern of GH9 genes reveal their critical roles during fruit abscission zone formation in Vaccinium ashei.

Transcriptome differential expression analysis of defoliation of two different lemon varieties

“…The development and functional exercise of the abscission layer is a complex and precise process in which multiple enzymes ( Tong et al, 2020 ; Wang et al, 2023 ), hormones ( Kućko, Wilmowicz & Ostrowski, 2019 ; Li et al, 2023 ), and genes ( Wang et al, 2021 ; Ma et al, 2022 ) are involved in regulation. Abscission is a physiological process associated with stress response and plant organ senescence.…”

“…The direct cause of plant organ abscission is the degradation of the cell wall, which in turn is due to several associated cellulases ( Wang et al, 2023 ; Li et al, 2019 ), pectinases ( Bai et al, 2023 ), peroxidases ( Djanaguiraman et al, 2010 ), polygalacturonases ( Hu et al, 2023 ; He et al, 2023 ; Bonghi et al, 1992 ), xyloglucan endoglucan transglucosylase/hydrolyzing enzymes ( Wang et al, 2022 ; Niederhuth, Patharkar & Walker, 2013 ), and extender proteins that lead to the disruption of cell-to-cell adhesion ( Patharkar & Walker, 2018 ; Botton & Ruperti, 2019 ).…”