Influence of Salt Stress on Proline and Glycine Betaine Accumulation in Tomato (Solanum lycopersicum L.)

Abstract

Many plants accumulate high levels of free proline content (pro) and glycine betaine (GB) in response to abiotic stress, Pro and GB act as an osmoprotectant. Generally, these levels are high than those required to be used in protein synthesis. Salinity inhibition of plant growth is the result of osmotic and ionic effect and different plant species have developed different mechanisms to cope with those effects. In this study, accumulation of osmolytes of twenty tomato genotypes was evaluated in response to salinity stress. The seedlings of each genotype were divided into three groups, Sodium chloride (NaCl) dissolved in irrigation water to make variant concentration of 30 and 60 mg/L of salt concentration using electrical conductivity meter which were used to water the plants. Level of free proline and glycine betaine were measured. Data obtained were subjected to one way analysis of variance using SPSS (20) Statistical Software. Dry mass accumulation decreased with increased salt concentration in all the genotypes. However, the result differ significantly (P< 0.05). The highest dry mass accumulations at control were recorded on Tropimech and Giofranco F. with 6.00 and 5.97. The lowest dry mass accumulations were recorded on plant treated with 60mg/L of salt. Dangainakawa recorded the least accumulation of dry mass on plants treated with 60mg/l of salt with 0.90g followed by Dan Gombe with 1.47g respectively. The highest free proline content of 1.46 µmolg-1was recorded on Dan gainakawa at plant treated with 60 mg/L of NaCl. The lowest proline content was recorded at control on Giofranco F. with 0.17 µmolg-1The highest GB content in all the plants were recorded at plants treated with 60 mg/L. However, the highest GB content (1.67) among the 20 (P<0.05) were recorded at 60 mg/L in Rio Grande followed by Bahaushe with 1.50 µmolg-1. In conclusion, GB and Pro are osmoregulators produced by tomato in response to stress so as to alleviate the consequence effects of salt stress.