The xanthine dehydrogenase (XDH), a molybdenum-containing oxidoreductase belonging to the molybdenum hydroxylase flavoprotein family, has been identified in a variety of eukaryotes, bacteria, and archaea. XDH catalyzes the conversion of xanthine and hypoxanthine to uric acid, which then undergoes further reactions to form allantoin and allantoic acid. Studies have shown that XDH plays a role in various metabolic processes, including purine metabolism, nitrogen metabolism, hormone metabolism, reactive oxygen species metabolism, and responses to biotic and abiotic stresses. Here, we introduced the structural features, metabolic pathways, and biological functions of XDH. In addition, we summarized the research progress in XDH to give insights into the molecular mechanism of purine metabolism in plants and prospected the application of XDH, with the aim to facilitate future research on the growth, development, and stress resistance of crops.

Calcium-dependent protein kinases (CDPKs/CPKs) are members of the Ca²⁺-sensitive Ser/Thr protein kinase family and play a crucial role in plant growth and development and responses to abiotic stress. CDPKs are capable of rapidly sensing changes in intracellular Ca²⁺ signals and recognizing and phosphorylating specific substrates, thereby transmitting and amplifying Ca²⁺ signal cascades downstream. They are involved in plant responses to stress conditions such as drought, saline-alkali stress, and injuries and regulate plant growth and development, gene expression, ion channel activity, and stomatal movement. The autophosphorylation of CDPKs can affect their activities and substrate specificity. CDPKs have the ability to bind to and phosphorylate multiple substrates. In addition to participating in respiratory burst oxidase homolog (RBOH), mitogen-activated protein kinase (MAPK), and plant hormone signaling pathways, CDPKs can also bind to 14-3-3 proteins, which enables the regulation of plant responses to stress and promotes plant growth and development. This paper summarized the research findings on the discovery, structure, classification, and roles of CDPKs in plant responses to stress and proposed the future research directions, aiming to provide the genetic resources and a theoretical basis for improving the stress tolerance of crops.

Camellia oleifera is an important woody oil crop in China, and its seed oil has a high economic value. Anthracnose, one of the main diseases in C. oleifera, occurs in a wide range in the production areas, limiting the growth and development of plants and causing serious losses of oil production. With the rapid development of the C. oleifera industry in recent years, great progress has been achieved in the research on anthracnose in C. oleifera. This paper summarized the resistance mechanisms, the mining of resistance genes, and the evaluation of resistant germplasm resources, aiming to provide a theoretical basis for the prevention and control of anthracnose and the breeding of C. oleifera germplasm with resistance to anthracnose.