The SpAHA1 gene, encoding a plasma membrane (PM) H-ATPase (AHA) in Sesuvium portulacastrum, was transformed into Arabidopsis plants, and its expression increased salinity tolerance of transgenic Arabidopsis plants: seed germination ratio, root growth, and biomass of transgenic plants were greater compared to wild-type plants under NaCl treatment condition. Upon salinity stress, both Na and H effluxes in the roots of SpAHA1 expressing plants were faster than those of untransformed plants. Transformed plants with SpAHA1 had lower Na and higher K contents relative to wild-type plants when treated with NaCl, resulting in greater K/Na ratio in transgenic plants than in wild-type plants under salt stress. Extent of oxidative stress increased in both transgenic and wild-type plants exposed to salinity stress, but overexpression of SpAHA1 could alleviate the accumulation of hydrogen peroxide (HO) induced by NaCl treatment in transgenic plants relative to wild-type plants; the content of malondialdehyde (MDA) was lower in transgenic plants than that in wild-type plants under salinity stress. These results suggest that the higher H-pumping activity generated by SpAHA1 improved the growth of transgenic plants via regulating ion and reactive oxygen species (ROS) homeostasis in plant cells under salinity stress.

Anthracnose is a destructive disease that affects a wide range of crop plants especially in tropical and subtropical regions. Colletotrichum spp. are the major pathogens causing anthracnose. In this study, we collected and identified the pathogen from diseased samples of Stylosanthes, a major tropical forage crop. The ability of the pathogen to naturally infect Arabidopsis thaliana was examined. Sequence analysis of ITS, ACT, CHS, and GAPDH genes showed the pathogen to be Colletotrichum gloeosporioides sensu lato (s.l.), and this was supported further by morphological characterization of representative isolates. The disease symptoms and cellular infection process of aggressive isolates (DZ‐19 and HK‐04) and a weak isolate (CJ‐04) were compared. DZ‐19 and HK‐04 caused more severe disease symptoms on both young seedlings and adult plants of Col‐0 and Ws‐2 ecotypes compared to CJ‐04. Furthermore, the more aggressive isolates showed faster and earlier germination of conidia, formation of appressoria, and growth and development of hyphae during the infection. Genetic analysis of the defence response and expression profiling of defence marker genes demonstrated the involvement of MAP kinase, Ca2+‐dependent protein kinase, salicylic acid, ethylene, and jasmonic acid pathways in the resistance against anthracnose. These results suggest that the Arabidopsis–Colletotrichum gloeosporioides pathosystem should provide a valuable tool for exploring the resistance mechanisms against this pathogen.