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Morphological structure and physiological research of heterophylly in Potamogeton octandrus

Li, Xiaoxia, He, Dingxuan, Guo, Youhao
Plant systematics and evolution 2019 v.305 no.3 pp. 223-232
Potamogeton, abscisic acid, aquatic plants, chlorophyll, gibberellic acid, hormones, indole acetic acid, leaves, stomata
Heterophylly is regarded as a manifestation of aquatic plants adapting to environment in evolutionary process. We studied the morphological and anatomical structure of submerged and floating leaves of Potamogeton octandrus. The changes of four endogenous hormones levels during the development of heterophylly were measured. The results showed that the epidermis thickness of floating leaves increased significantly compared with submerged leaves. The stomata only distribute on floating leaves, and the upper epidermis had obvious wax. While the submerged leaf epidermis was smooth and had no waxy ornamentation, chlorophyll content of floating leaves was significantly higher than that of submerged leaves. The four endogenous hormones showed a different change pattern in the development process of submerged and floating leaves. ABA content showed a trend of increased first and then decreased in the development of submerged leaves, while it gradually increased in floating leaves. GA₃ content decreased significantly in the development of floating leaves, but showed an upward trend in submerged leaves. ZT content generally increased during the development of submerged and the floating leaves, while IAA content was the highest in the shoot and then declined rapidly. The difference characteristics in submerged and floating leaves can be considered as adaptation mechanism in plants development, and the four endogenous hormones may play different roles in development stages of heterophylly.