Why aba can be used as a signal factor of adversity stress?

Because aba plays a key role in the regulation of plant growth and development. Aba, abscisic acid, is a trace organic substance produced in plants, but it plays a key role in the regulation of plant growth and development. It can not only inhibit the growth, but also make plants react quickly under adversity, thus enhancing the stress resistance of plants. Especially in drought resistance, aba can regulate the physiological process of plants, in which aba content increases rapidly, causing stomata to close, reducing transpiration and enhancing drought resistance. So aba can be used as a signal factor of adversity stress.