Wheatley, Andrew O.; Ahmad, Mohammed H.; Asemota, Helen N.
Author Affiliation, Ana.
Department of Basic Medical Sciences
Development of salt adaptation in vitro greater yam (Dioscorea alata) plantlets
In Vitro Cellular & Developmental Biology : Journal of the Tissue Culture Association
Date of Publication
The development of plants capable of growing under saline conditions is one approach at utilizing saline soils that are otherwise arable. This study was designed to develop salt-tolerant yam (Dioscorea alata) plantlets, using tissue culture techniques. Salt-tolerant yam (Dioscorea alata cv. Sweet yam) plantlets were produced in vitro through repeated culturing and selection on saline media. Two hundred plantlets were subcultured on normal multiplication media (Murashige and Skoog basal media with 30 g l-1 sucrose and 0.44 ÁM benzylaminopurine). A further 400 plantlets were equally subcultured on multiplication media supplemented with 100 or 200 mM NaCl. Plantlets that proliferated on medium with 100 mM saline conditions were repeatedly subcultured on saline media. Growth of plantlets and root formation were assessed along with some biochemical parameters such as invertase (EC 220.127.116.11), peroxidase (EC 18.104.22.168), and polyphenol oxidase (EC 22.214.171.124) activities. No growth was observed for plantlets transferred to the highly saline media of 200 mM NaCl and the explants did not survive beyond 6 wk. Control plantlets exhibited 100% rooting within 3 wk compared to 5 wk for plantlets on 100 mM NaCl. Development of new nodes and leaves were observed for plantlets on 100 mM NaCl, although at an initially slower rate than the control plantlets. The enzyme activity profiles obtained for plantlets on 100 mM NaCl reflected the biochemical adjustments of the plantlets to cope with the saline conditions. This was further substantiated by the detection of two reproducible bands of sizes 1 and 0.35 kb from reverse transcription polymerase chain reaction (RT-PCR) studies of salt-tolerant yam plantlets. These results can be translated into efforts aimed at maximizing the use of saline soils.....