Animals, materials and methods
All experiments were approved by the regional board (Kunming Institute of Botany, Chinese Academy of Sciences) in accordance with the Chinese animal welfare law, as well as in accordance with local regulations and the NRC Guide for the Care and Use of Laboratory Animals and approved by the local Institutional Animal Care and Use Committee (the Animal Ethics Committee of Kunming Institute of Botany, Chinese Academy of Sciences, No. KIB-SMP-019).