Stimulatory Effect of Thidiazuron Manipulation on Regeneration of Mature Caryopsis Culture in Bread Wheat (Triticum aestivum L.) and Pasta Wheat (Triticum durum L.)

Abstract: A comparative study was aimed to evaluate the morphogenic response of thidiazuron (TDZ) a novel morphogen, in the Murashige and Skoog (MS) nutrient medium on mature caryopsis culture of hexaploid bread wheat (Triticum aestivum L. cv. HD2329) and tetraploid pasta wheat (Triticum durum L. cv. PDW215). To begin with, mature caryopsis exhibits slow and inhibited germination followed by semi-compact callus formation from the basal region of growing coleoptiles on nutrient medium supplemented with 2, 4-dichlorophenoxyacetic acid (2, 4-D) alone or in combination with either 6-benzylaminopurine (BAP) or TDZ. In contrary, caryopses cultured on either BAP or TDZ alone supplemented medium, show direct multiple-shoot regeneration instead of callusing from the base of developing coleoptiles. Furthermore, results indicate that mature caryopses of both wheat varieties show significant improvements in frequency of multiple-shoot regeneration (53%) and (39%) respectively on manipulation of TDZ concentration in combination with BAP. Thus, TDZ proves to be stimulatory in terms of multiple-shoot regeneration from caryopsis culture. However, other treatments such as 2, 4-D either with TDZ or BAP reflected very weak combinations and failed to contribute any effective roles in regeneration of both wheat varieties. Hence, the results involving the stimulatory response of TDZ for mature caryopsis regeneration in wheat suggest that further investigations are required to understand the molecular involvement of TDZ during cellular metabolic pathways and its interaction with BAP during in vitro cell regeneration.