Effects of Exogenous Glycine Betaine and Cycloleucine on Photosynthetic Capacity, Amino Acid Composition, and Hormone Metabolism in Solanum melongena L

Abstract

Although exogenous glycine betaine and cycloleucine have been reported to affect animal cell metabolism, their effects on plant growth and development have not been studied extensively. Different concentrations of exogenous glycine betaine (20, 40, and 60 mmol L− 1) and cycloleucine (10, 20, and 40 mmol L− 1), with 0 mmol L− 1 as control, were used to investigate the effects of foliar spraying of betaine and cycloleucine on growth, photosynthesis, chlorophyll fluorescence, Calvin cycle pathway, abaxial leaf burr morphology, endogenous hormones, and amino acid content in eggplant. We found that 40 mmol L− 1 glycine betaine had the best effect on plant growth and development; it increased the fresh and dry weight of plants, increased the density of abaxial leaf hairs, increased the net photosynthetic rate and Calvin cycle key enzyme activity of leaves, had an elevating effect on chlorophyll fluorescence parameters, increased endogenous IAA content and decreased ABA content, and increased glutamate, serine, aspartate, and phenylalanine contents. However, cycloleucine significantly inhibited plant growth; plant apical dominance disappeared, plant height and dry and fresh weights decreased significantly, the development of abaxial leaf hairs was hindered, the net photosynthetic rate and Calvin cycle key enzyme activities were inhibited, the endogenous hormones IAA and ABA content decreased, and the conversion and utilization of glutamate, arginine, threonine, and glycine were affected. Combined with the experimental results and plant growth phenotypes, 20 mmol L− 1 cycloleucine significantly inhibited plant growth. In conclusion, 40 mmol L− 1 glycine betaine and 20 mmol L− 1 cycloleucine had different regulatory effects on plant growth and development.

Preventive-Glycine Betaine Treatment Mitigate Spring and Summer Chilling Damage on Young Chestnut Trees under Climate Variability in Southern Chile

“…It should be noted that on our studied chestnut plants +GB stimulated the vegetative growth of trees even after they have been suffered frost damage in summer. Glycine-Betaine is one of the most effective compatible solutes and it protects cellular structures from stresses by maintaining an osmotic balance and stabilizing the quaternary structures of complex proteins [18]. Concomitant with our findings, an increase in growth and development was observed in eggplant (Solanum melongena) [19] and in Strawberry (Fragaria x annanasa) cultivars Fortune and Albion treated with GB compared to control [8].…”

“…Chlorophyll is an important photosynthetic pigment, largely determining photosynthetic capacity and hence plant growth. Indeed, foliar application of GB in tomato, considerably enhanced chlorophyll content under stress condition [18,23,27]. The AN measured in the month of January was significantly higher for +GB (16.48 µ mol CO2 m -2 s -1 ) treatment compared to the control 11.93 µ mol CO2 m -2 s -1 ), respectively.…”