Molecular regulation by HS of antioxidant and glucose metabolism in cold-sensitive Capsicum.

BACKGROUND

Cold is an important environmental limiting factor affecting plant yield and quality. Capsicum (chili pepper), a tropical and subtropical vegetable crop, is extremely sensitive to cold. Although HS is an important signaling regulator in the responses of plant growth and development to abiotic stress, few studies have examined its effects on cold-sensitive capsicum varieties. Through biotechnology methods to enhance the cold resistance of peppers, to provide some reference for pepper breeding, investigated molecular regulation by HS of responses to cold stress in cold-sensitive capsicum plants, via physiological and transcriptomic analyses.

RESULTS

In capsicum seedlings, exogenous HS enhanced relative electrical conductivity (REC) and levels of malondialdehyde (MDA) under cold stress, maintained membrane integrity, increased the activity of enzymatic and non-enzymatic antioxidants, balanced reactive oxygen species levels (O and HO), and improved photosynthesis, mitigating the damage caused by cold. In addition, 416 differentially expressed genes (DEGs) were involved in the response to cold stress after HS treatment. These DEGs were mainly enriched in the ascorbate-glutathione and starch-sucrose metabolic pathways and plant hormone signal-transduction pathways. Exogenous HS altered the expression of key enzyme-encoding genes such as GST, APX, and MDHAR in the ascorbate-glutathione metabolism pathway, as well as that of regulatory genes for stimulatory hormones (auxin, cytokinins, and gibberellins) and inhibitory hormones (including jasmonate and salicylic acid) in the plant hormone signal-transduction pathway, helping to maintain the energy supply and intracellular metabolic stability under cold stress.

CONCLUSIONS

These findings reveal that exogenous HS improves cold tolerance in cold-sensitive capsicum plants, elucidating the molecular mechanisms underlying its responses to cold stress. This study provides a theoretical basis for exploring and improving cold tolerance in capsicum plants.