In vitro plant regeneration, screening for salt and drought tolerance in sugarcane (Saccharum Spp.)

Abstract

Soil salinity and drought are some of the major sugarcane production factors in Ethiopia. This investigation was conducted to develop, screen and select salt and drought tolerant genotypes under in vitro condition. Both direct and indirect pathways were employed in the development and selection of salt and drought tolerant lines from the commercial varieties. In all cultures, explants were inoculated to Murashige and Skoog (MS) medium supplemented with inhibitory levels of NaCl (0, 30, 100, 170 & 240 mM) and polyethylene glycol (0, 2.5, 5, 7.5 & 10%) concentrations. During callus induction, data for percent of explants induced callus and its morphological status were collected to evaluate varieties, and select healthy, salt and polyethylene glycol (PEG) tolerant calli. Moreover, shoot regeneration percentage, shoot Vigrousity and color were taken as major criteria to select stress (salt and PEG) tolerant shoot while data for plantlet root attributes were collected to screen stress tolerant plantlets. Results of the study indicated that health and salt tolerant calli and shoots were identified at MS medium supplemented with 170 Mm while 10% PEG was the best selection medium to select healthy and PEG tolerant calli and shoots. Our screening results suggested that the in vitro developed regenerants were more discriminated at 240 mM NaCl where S4SP-70-1284, S4 C0-501 and S2B-78-505 were selected as salt tolerant regenerants. Moreover, more variability was observed at MS medium induced with 10% polyethylene glycol where regenerants D4C-132-81, D5C-132-81, D3B52-298, D2B52-298 and D4B52-298 showed better degree of tolerance to drought. The dendrogram separated those regenerants developed through direct regeneration from those regenerants developed through indirect regeneration. It suggested the existence of somaclonal variation. Moreover, both dendrograms were capable of separating those regenerants exhibiting tolerance to the stresses in question thereby suggesting the existence of variability in relation to stress tolerance. We recommend these regenerants be used as a source of variability for future stress breeding studies. Moreover, these regenerants can be used as alternative varieties at salt affected and soil moisture limited fields of sugarcane production areas. However, it should be further evaluated for yield and yield quality before using for commercial purposes.