Phenylalanine Ammonia Lyase GmPAL1.1 Promotes Seed Vigor under High-Temperature and -Humidity Stress and Enhances Seed Germination under Salt and Drought Stress in Transgenic Arabidopsis

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, GmPAL1.1 was cloned from soybean, and its protein was located in the cytoplasm and cell membrane. GmPAL1.1 was significantly induced by HTH stress in developing seeds. The overexpression of GmPAL1.1 in Arabidopsis (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 of GmPAL1.1 in Arabidopsis enhanced the tolerance to salt and drought stresses during germination. Our results suggested the overexpression of GmPAL1.1 in Arabidopsis promoted seed vigor at the physiological maturation period under HTH stress and increased the seeds' tolerance to salt and drought during germination.

Huang Qin Hua Shi decoction for high-temperature- and high-humidity-induced cognitive-behavioral disorder in rats is associated with deactivation of the hypothalamic-pituitary-adrenal axis

Objective

To investigate the effects of Huang Qin Hua Shi (HQ) decoction on the hypothalamic–pituitary–adrenal (HPA) axis in rats under high-temperature (hT)- and high-humidity (hH)-induced stress.

Methods

Male rats were randomized into four groups: rats without stress; rats induced with hT (35 ± 1°C) and hH (85 ± 5% humidity); rats induced with hT and hH and treated with HQ decoction; and rats induced with hT and hH and treated with mifepristone. After 3 weeks, rats underwent the Morris water maze and open-field test. Rat hypothalami were analyzed pathologically using hematoxylin and eosin staining and glucocorticoid receptor (GR) mRNA expression was evaluated by in situ hybridization. Serum levels of corticotropin-releasing hormone (CRH), adrenocorticotropic hormone (ACTH), and corticosteroid (CORT) were assessed by enzyme-linked immunosorbent assay.

Results

The administration of mifepristone or HQ in stressed rats significantly improved their performance in the Morris water maze test and increased the central-to-peripheral ratio and incidence of deep rearing in the open-field test. Mifepristone and HQ also reversed histological changes in the hypothalami of stressed rats. Compared with control rats, GR mRNA expression in the hypothalamus and serum CRH, ACTH, and CORT were significantly elevated in rats stressed with hT and hH, and these changes were attenuated by mifepristone and HQ.

Conclusion

HQ decoction protects against hT- and hH-induced cognitive-behavioral disorder and its therapeutic effect is associated with decreased HPA axis activity.