Contribution of Glycine Betaine and Proline to Water Deficit Tolerance in Pepper Plants

Abstract

43 #130, Col. Chuburn a de Hidalgo, 97200 M erida, Yucat an, M exico Additional index words. Water potential, relative water content, osmolytes, electrolyte leakage, drought stress, pepperAbstract. Water stress is the main factor responsible for decreased productivity, which affects the growth and development of crops. Plants respond to stress by accumulating compatible solutes, which have a key role in osmotic adjustment, thereby resulting in osmoprotection of the plants. The loss of water can increase the concentration of compatible osmolytes and molecules that regulate the plant metabolism. These solutes can be metabolized as sugars (sucrose, fructose, trehalosa), amino acids (proline), an amphoteric quaternary amine (glycine betaine), and other low-molecular-weight metabolites. However, among all these compatible solutes, proline and glycine betaine occur the most. Proline is an amino acid that can accumulate in low concentrations under optimal conditions; however, stress conditions contribute to its increased content. Few data are available regarding the levels of endogenous glycine betaine on Solanaceae, which is considered a nonaccumulator under water deficit conditions. The objective of this research was to evaluate the role of compatible osmolytes, glycine betaine and proline, in Capsicum sp. plants under different water deficit conditions. In this study, the presence of endogenous levels of proline and glycine betaine in two species of pepper (Capsicum chinense var. Genesis and Rex and Capsicum annuum var. Padron) were found. The concentration levels of proline were 362, 292, and 246 mmol · g L1 DW for Genesis, Rex and Padron respectively, and irrigation conditions (rehydration) of proline levels increased to 381, 395, and 383 mmol · g L1 DW at 21 days. However, glycine betaine levels were 30-70 mmol · g L1 DW. The relative water content, electrolyte leakage, and soil water potential were also analyzed; therefore, the information suggests that proline contributes better to tolerance to water deficit in the genus Capsicum after 14 days of water deficit treatment. It seems that the contribution of glycine betaine is less effective than that of proline; therefore, it does not have an important role in osmotic adjustment.

Response and Defence Mechanisms of Vegetable Crops against Drought, Heat and Salinity Stress

“…It is generally coinciding with high air temperatures which increase plant evapotranspiration, thus resulting in stomatal closure and reduced photosynthetic activity and yield [28][29][30]. The severe effects of drought stress on crops accounts to billions of dollars globally, especially in the arid and semi-arid regions of [31][32][33]. The incidents of drought are becoming more and more frequent [30], due not only to temperature rise, but also to excessive and irrational use of natural resources and soil desertification [34].…”

Responses of woody plant Dalbergia odorifera treated with glycine betaine to drought and cold stresses: involvement of the alternative oxidase

“…Also, Chen and Murata (2008) suggested that one of the roles of GB might be to protect cell membranes. Furthermore, the accumulation of GB in the pepper plant contributed to the protection of membrane damages caused by water deficit (Escalante-Magaña et al 2019). Drought and cold as abiotic stresses can trigger oxidative stress in plants that is due to overproduction and accumulation of ROS.…”

Thiamin stimulates growth, yield quality and key biochemical processes of cauliflower (Brassica oleracea L. var. Botrytis) under arid conditions

“…We observed that compatible osmolytes (GB and proline) significantly increased in both leaf and head of cauliflower cultivars under water-deficit stress. In general, high accumulation of GB and proline has already been reported to be associated with drought stress tolerance [ 50 , 57 ]. For example, better growth of drought stressed maize plants has already been associated with higher levels of GB and proline accumulation, one of the important aspects of osmotic adjustment under stress conditions [ 5 ].…”