GABA responds to low phosphorus stress by interfering with endogenous auxin levels in apple
Chen, Xiao, Yuchen Tian, Yuanmei Xie, Yu Liu, Qianwei Liu, Fengwang Ma, Wenting Zhang and Cuiying Li
Plant and Soil
Background and aims As the immobility of inorganic phosphorus (P) in soil, the acquisition of P by sessile plants is limited. ?-Aminobutyric acid (GABA) as a signal molecule and a metabolite can regulate plants to cope with various stresses. However, whether GABA could contribute to the adaption to low P stress in apple plants remains unclear.Methods This study combined different methods to detect the induction of auxin (IAA) synthesis by GABA to improve the tolerance of apple seedlings to low P stress (including growth and development analysis, reactive oxygen species (ROS) clearance effect, root structure analysis, multiple factorial analysis (MFA), gene expression analysis).Results Exogenous GABA improved the growth of apple seedlings under low P conditions, reduced the ROS accumulation, and promoted the photosynthetic capacity. GABA contributed to the root system architecture and the development of mature area of root tips. In addition, the intervention of exogenous GABA interfered with the homeostasis of endogenous IAA and activated the expression of P starvation induction (PSI) gene, leading to the significantly i0ncrease of the P uptake in apple plants. Meanwhile, transgenic roots with overexpressing MdGAD1 enhanced the tolerance of apple seedlings to low P stress, improved the root development through regulating IAA signaling pathway, and significantly improved the P uptake of apple seedlings under low P conditions.Conclusion All results suggested that GABA could contribute to the adaption of apple seedlings to low P conditions, by decreasing ROS accumulation, maintaining photosynthetic capacity, and increasing IAA level to improve the root development and the P absorption.