Abscisic acid (ABA), one of the six major plant hormones, plays an essential and irreplaceable role in numerous physiological and biochemical processes during normal plant growth and in response to abiotic stresses. It is a key factor in balancing endogenous hormones and regulating growth metabolism in plants. The level of ABA is intricately regulated through complex mechanisms involving biosynthesis, catabolism, and transport. The functionality of ABA is mediated through a series of signal transduction pathways, primarily involving core components such as the ABA receptors PYR/PYL/RCAR, PP2C, and SnRK2. Over the past 50 years since its discovery, most of the genes involved in ABA biosynthesis, catabolism, and transport have been characterized, and the network of signaling pathways has gradually become clearer. Extensive research indicates that externally increasing ABA levels and activating the ABA signaling pathway through molecular biology techniques significantly enhance plant tolerance to abiotic stresses and improve plant productivity under adverse environmental conditions. Therefore, elucidating the roles of ABA in various physiological processes of plants and deciphering the signaling regulatory network of ABA can provide a theoretical basis and guidance for addressing key issues such as improving crop quality, yield, and stress resistance.

In Changbai Mountains, Panax ginseng (ginseng) was cultivated in a mixture of the humus and albic horizons of albic luvisol in a raised garden with plastic shade. This study aimed to evaluate the impact of ginseng planting on soil characteristics. The mixed-bed soils were seasonally collected at intervals of 0-5 cm, 5-10 cm, and 10-15 cm for different-aged ginsengs. Soil physico-chemical characteristics were studied using general methods. Aluminum was extracted from the soil solids with NH4Cl (exchangeable Al) and Na-pyrophosphate (organic Al) and was measured with an atomic absorption spectrophotometer. A remarkable decrease in the pH, concentrations of exchangeable calcium, NH4 (+), total organic carbon (TOC), and organic Al, as well as a pronounced increase in the bulk density were observed in the different-aged ginseng soils from one spring to the next. The decrease in pH in the ginseng soils was positively correlated with the [Formula: see text] (r = 0.463, p < 0.01), exchangeable calcium (r = 0.325, p < 0.01) and TOC (r = 0.292, p < 0.05) concentrations. The [Formula: see text] showed remarkable surface accumulation (0-5 cm) in the summer and even more in the autumn but declined considerably the next spring. The exchangeable Al fluctuated from 0.10 mg g(-1) to 0.50 mg g(-1) for dry soils, which was positively correlated with the [Formula: see text] (r = 0.401, p < 0.01) and negatively correlated with the TOC (r = -0.329, p < 0.05). The Al saturation varied from 10% to 41% and was higher in the summer and autumn, especially in the 0-5 cm and 5-10 cm layers. Taken together, our study revealed a seasonal shift in soil characteristics in ginseng beds with plastic shade.

Significance: The Trp triad-dependent photoreduction of the flavin chromophore has been widely accepted as the photoexcitation mechanism of cryptochrome photoreceptors. However, the experimental evidence supporting this hypothesis derived primarily from the biophysical studies in vitro, except for one genetics study of Arabidopsis cryptochrome 1 (CRY1). In contrast to the previous report, we found that all Trp-triad mutations of Arabidopsis CRY1 remained physiologically active in plants, and this result cannot be readily explained by the ATP-dependent enhancement of Trp triad-dependent photoreduction. Our results challenge the widely accepted Trp-triad hypothesis and call for further investigation of alternative electron transport mechanisms to explain cryptochrome photoexcitation.

As an important signal molecule, salicylic acid (SA) improves plant tolerance to aluminum (Al) stress. The objective of this study was to investigate the effects of exogenous SA application on the dynamics of endogenous SA and reactive oxygen species in soybean (Glycine max L.) exposed to Al stress. The roots of soybean seedlings were exposed to a combination of AlCl3 (30 μM) and SA (10 μM)/PAC (100 μM, paclobutrazol, SA biosynthesis inhibitor) for 3, 6, 9 and 12 h. Al stress induced an increase in endogenous SA concentration in a time-dependent manner, also verified by the up-regulated expression of GmNPR1, an SA-responsive gene. Al stress increased the activities of phenylalanine ammonia-lyase (PAL) and benzoic acid 2-hydroxylase (BA2H), and the contents of SA, O2- and malondialdehyde (MDA) in the root apex. The application of exogenous SA increased PAL and BA2H, and reduced O2- and MDA contents in soybean roots under Al stress. PAC inhibited the SA induced increase in BA2H activity. In addition, the SA application resulted in a rapid increase in hydrogen peroxide (H2O2) concentration under Al stress, followed by a sharp decrease. Compared with the plants exposed to Al alone, Al+SA plants possessed higher activities of superoxide dismutase, peroxidase and ascorbate peroxidase, and lower catalase activity, indicating that SA alleviated Al-induced oxidative damage. These results suggested that PAL and BA2H were involved in Al-induced SA production and showed that SA alleviated the adverse effects of Al toxicity by modulating the cellular H2O2 level and the antioxidant enzyme activities in the soybean root apex.