Abstract

Seed vigor is an important agronomic attribute, essentially associated with crop yield. High-temperature and humidity (HTH) stress directly affects seed development of plants, resulting in the decrease of seed vigor. Therefore, it is particularly important to discover HTH-tolerant genes related to seed vigor. Phenylalanine ammonia lyase (PAL, EC 4.3.1.24) is the first rate-limiting enzyme in the phenylpropanoid biosynthesis pathway and a key enzyme involved in plant growth and development and environmental adaptation. However, the biological function of PAL in seed vigor remains unknown. Here,GmPAL1.1was cloned from soybean, and its protein was located in the cytoplasm and cell membrane.GmPAL1.1was significantly induced by HTH stress in developing seeds. The overexpression ofGmPAL1.1inArabidopsis(OE) accumulated lower level of ROS in the developing seeds and in the leaves than the WT at the physiological maturity stage under HTH stress, and the activities of SOD, POD, and CAT and flavonoid contents were significantly increased, while MDA production was markedly reduced in the leaves of the OE lines than in those of the WT. The germination rate and viability of mature seeds of the OE lines harvested after HTH stress were higher than those of the WT. Compared to the control, the overexpression ofGmPAL1.1inArabidopsisenhanced the tolerance to salt and drought stresses during germination. Our results suggested the overexpression ofGmPAL1.1inArabidopsispromoted seed vigor at the physiological maturation period under HTH stress and increased the seeds’ tolerance to salt and drought during germination.Keywords:GmPAL1.1;seed vigor;high-temperature and high-humidity stress;salt stress;drought stress;ROS