IN VITRO SELECTION OF CALLI FOR SALT TOLERANCE IN TOMATO (Solanum lycopersicurn L.)

Abstract

Soil salinity is one of the most important abiotic stresses that limit crop production. Responses of six breeding lines (J3D-7755. BD-7757, RD-9008, BD-901 I, BD-10122, )3D-10123 which were named as GI, 62.03,04. 05 and 66 respectively) of tomato (Solanurn lycopersicun: I.) to NaCl stress were studied in callus induction. Hypocotyl and cotyledon segments were chosen as explants for callus induction in vitro. The six investigated tomato genotypes differed in their callus growth. Tomato seeds were cultured for callus formation and that callus were treated with 0 mM (control), 50 mM, 100 mM, 150 mM and 200 mM NaCl in nutrient solutions. The effect of the stress applied on the callus was evaluated in 10 DAT (Days After Treatment) and 17 DAT. Different concentrations of NaCl in the medium significantly affected the hiomass callus size and callus weight of tomato. 02 and 06 showed excellent performance of tolerance up to 50 mM of NaCl. 06 showed better performance under high salt concentrations i.e., at 100 mM and 200 mM but not at low salt stress. It indicates the expression of functional gene occurs at high salt stress. However it is possible to select callus line tolerant to elevated levels of NaCI stress by sudden exposure to high of NaCl. accordingly a NaCl tolerant cell line was selected from hypocotyls and cotyledon derived callus of tomato which proved to he a true cell line variant. The interaction effect of variety and treatment revealed that genotype 06 and GI were the highcst and lowest performer respectively. These findings indicated some salt tolerant tomato genotypes which will be promising for regeneration and for future breeding program. It is quiet necessary to asses accumulation of proline and the anti-oxidant enzymes like Super Oxide Dismutase, Ascorhatc Pcroxidase and Catalase from the control and stressed callus as they are the indicator of salt tolerance. It is evident that tissue culture technique was able to evaluate several genotypes for salt tolerance into cell level under controlled environment with relatively littLe space and less time required comparing with such process studies at the whole plant level.