Molecular functions of nitric oxide and its potential applications in horticultural crops

Nitric oxide(NO)regulates plant growth,enhances nutrient uptake,and activates disease and stress tolerance mechanisms in most plants,making NO a potential tool for use in improving the yield and quality of horticultural crop species.Although the use of NO in horticulture is still in its infancy,research on NO in model plant species has provided an abundance of valuable information on horticultural crop species.Emerging evidence implies that the bioactivity of NO can occur through many potential mechanisms but occurs mainly through S-nitrosation,the covalent and reversible attachment of NO to cysteine thiol.In this context,NO signaling specifically affects crop development,immunity,and environmental interactions.Moreover,NO can act as a fumigant against a wide range of postharvest diseases and pests.However,for effective use of NO in horticulture,both understanding and exploring the biological significance and potential mechanisms of NO in horticultural crop species are critical.This review provides a picture of our current understanding of how NO is synthesized and transduced in plants,and particular attention is given to the significance of NO in breaking seed dormancy,balancing root growth and development,enhancing nutrient acquisition,mediating stress responses,and guaranteeing food safety for horticultural production.

Comparative Experiment on Different Pepper Varieties in Solar Greenhouse in Lhasa Area

In order to screen the pepper varieties suitable for planting in the solar greenhouse in Lhasa, variety comparison test was conducted to the continuous cropping of pepper in solar greenhouse. The results showed that Qianlv Tianshi F_1, Oriental Changlong F_1 and Qujiao 1 F_1 had higher yields than the control, and significantly lower root incidence rates than the control. Therefore, the 3 varieties were suitable fro planting in Lhasa.

Melatonin: A master regulator of plant development and stress responses

Melatonin is a pleiotropic molecule with multiple functions in plants. Since the discovery of melatonin in plants, numerous studies have provided insight into the biosynthesis, catabolism, and physiological and biochemical functions of this important molecule. Here, we describe the biosynthesis of melatonin from tryptophan, as well as its various degradation pathways in plants. The identification of a putative melatonin receptor in plants has led to the hypothesis that melatonin is a hormone involved in regulating plant growth,aerial organ development, root morphology, and the floral transition. The universal antioxidant activity of melatonin and its role in preserving chlorophyll might explain its anti-senescence capacity in aging leaves. An impressive amount of research has focused on the role of melatonin in modulating postharvest fruit ripening by regulating the expression of ethylene-related genes.Recent evidence also indicated that melatonin functions in the plant's response to biotic stress,cooperating with other phytohormones and wellknown molecules such as reactive oxygen species and nitric oxide. Finally, great progress has been made towards understanding how melatonin alleviates the effects of various abiotic stresses, including salt, drought, extreme temperature, and heavy metal stress. Given its diverse roles, we propose that melatonin is a master regulator in plants.