Plant drought tolerance was enhanced by positively regulating endogenous protective enzymes activities and phytohormones levels in a clonal plant of A. trewioides

• trewioides performed clonal integration between mother and daughter plants by regulating antioxidant enzyme activities and phytohormone levels. • Clonal ramets up-regulated SOD, CAT and POD activities as well as ABA, BR and ZT levels to enhance their resistance to heterogeneous drought stress in mother or daughter plant. • These results were expected to provide a theoretical basis for understanding clonal integration characteristic to adapt to drought environmental surroundings in clonal plants. Clonal integration enables ramets to share resources by stolon, enhancing their adaptability to patches of heterogeneous resource supply in clonal plants. However, how clonal plants regulate photosynthetic capacity, endogenous protective enzymes and phytohormones to survive from heterogeneous drought were poorly understood. A pot experiment was conducted under heterogeneous drought conditions in mother and daughter plants in A. trewioides. Experiment treatments included (ⅰ) both well-watered mother and daughter plants (CK), (ⅱ) mother plant exposed to drought (SRWC of 45±5% for 9 days) + daughter plant well-watered (T 1 ), and (ⅲ) mother plant well-watered + daughter plant exposed to drought (T 2 ). Results showed that chlorophyll content and photosynthetic parameters were significantly reduced in drought plants whatever mother or daughter plants. However, daughter plants performed more vulnerable than mother plants when they were suffering from drought stress. Besides, hydrogen peroxide (H 2 O 2 ) and malondialdehyde (MDA) in mother plants were significantly increased for treatment T 1 compared with CK. In comparison, H 2 O 2, superoxide dismutase (SOD) and peroxidase (POD) were significantly increased by 41.87%, 15.68% and 11.70% in daughter plants for treatment T 1 compared with CK. Moreover, abscisic acid (ABA) level was remarkedly increased in mother plants for treatment T 1 relative to CK. Simultaneously, brassinosteroid (BR) and zeaxanthin (ZT) levels in daughter plants exhibited a significant increasing trend during rewatering stage for treatment T 1 relative to CK. Furthermore, SOD and catalase (CAT) in daughter plants were notably increased by 142.28% and 21.8% for treatment T 2 compared with CK. Interestingly, CAT and ABA were also increased by 33.54% and 19.6% in mother plants for treatment T 2 compared with CK. Therefore, we concluded that clonal plants could up-regulated SOD, CAT and POD activities as well as phytohormones such as ABA, BR and ZT levels both in mother and daughter plants whoever suffering from drought stress, more interestingly, mother plants would enhanced activities of some endogenous protective enzyme and phytohormone, eg. CAT and ABA, in despite of mother plant well-watered, when connected daughter plant was exposed to drought stress, thereby promoting their adaptive capacity. These results were expected to provide a theoretical basis for understanding physiological integration characteristic to promote their adaptions to drought environmental surroundings in clonal plants.