Genome-wide identification and functional annotation of the ascorbate peroxidase (APX) gene family in cotton: putative roles in reactive oxygen species (ROS) homeostasis within pigment glands
摘要
Expression of the APX gene and ROS levels in four Gossypium species are interrelated, functioning in cotton pigment gland development and abiotic stress responses.
AbstractAscorbate peroxidases (APXs) represent a crucial family of antioxidant enzymes that play essential roles in plant responses to environmental stresses and the regulation of developmental processes. Pigment glands in cotton are specialized structures formed through programmed cell death (PCD), a process inherently linked to the accumulation of reactive oxygen species (ROS). Despite the well-established functions of APXs in maintaining ROS homeostasis and the recognized involvement of ROS in pigment gland development, the specific interactions between APXs and ROS within these glands remain largely uncharacterized. In this study, bioinformatics approaches were employed to systematically analyze APX genes across multiple cotton varieties. Expression profiling revealed that APX genes exhibited both upregulated and downregulated responses to environmental stresses as well as hydrogen peroxide (H2O2) treatment, suggesting a potential dual-function mechanism for APXs in regulating ROS levels. Significant accumulation of ROS was observed in glands, while negligible levels were detected in glandless cotton. Comparative analysis indicated that most APX genes displayed higher expression levels in glanded cotton plants. Functional validation experiments demonstrated that overexpression and knockdown of GhMYC2-like—a key regulator involved in pigment gland formation—respectively induced and repressed the expression of six APX genes. These findings suggest that members of the APX family are integral components within the regulatory network governing cotton pigment gland formation. This study not only provides novel insights into the role of APXs within cotton biology but also establishes a solid foundation for future investigations into their functions related to ROS-mediated processes.