Abstract:

Abscisic acid（ABA）is an essential plant phytohormone for plant growth and development. It is involved in important processes such as the regulation of seed germination and dormancy, root growth, stomatal closure, leaf senescence, and abscission. Its function is mainly achieved through a series of signal transductions, and the first step of its signal transduction depends on the binding of its receptor. PYR1-like protein 9（PYL9）serves as a key receptor in the ABA signaling pathway, positioned upstream. Upon the detection of ABA signals, it suppresses the activity of protein phosphatase 2C（PP2C）, thereby activating SNF2-related protein kinase（SnRK2）and facilitating downstream gene's expression to initiate the ABA signaling cascade. This pivotal role contributes significantly to the regulation of plant stress resistance, as well as growth and development, by modulating abscisic acid signal transduction, cellular metabolism, and physiological and biochemical responses within plants. This paper provides a comprehensive review of the regulatory role of the ABA in plant growth, interactions with different hormone signals, synthesis and metabolic pathways, signal transduction composition and function, as well as the structure, functional characteristics, and important role and existing issues of ABA receptor PYL9 in stress response. The paper also prospects its application in future. It is also anticipated to offer a theoretical basis for systematic research on the function of ABA receptor gene PYL9 and mechanisms of plant antiviral defense reactions.

Key words: abscisic acid, PYL9, gene function, adverse stress, regulation mechanism