Effects of genotype and plant growth regulator on callus induction and plant regeneration in four important turfgrass genera: A comparative study

Turfgrass, like other major crop species, is recalcitrant to manipulation in vitro. To perform efficient genetic transformation of turfgrass, it is necessary to optimize tissue culture conditions. In most reports, plant tissue culture techniques have been applied to propagate a single cultivar or several cultivars in one species of turfgrass. In this experiment, four turfgrass genera were used, namely common bermudagrass, Cynodon dactylon [L.] Pers. (California origin); red fescue, Festuca rubra L. var. rubra 'Shadow'; perennial ryegrass, Lolium perenne L. 'Barbal'; and Kentucky bluegrass, Poa pratensis L. 'Merion.' Mature seeds were surface-sterilized and cultured on basal Murashige and Skoog (MS) media supplemented with 30-250 mu M 2,4-dichlorophenoxyacetic acid (2,4-D) for callus induction. Regeneration media consisted of MS supplemented with 5-10 mu M 6-benzyladenine (BA). Among the genera, Poa had the highest callus induction percentage (CIP) regardless of 2,4-D concentration, followed by Cynodon, Lolium, and Festuca, respectively. Cynodon and Lolium had the highest callus regeneration percentage (CRP) and overall regeneration rate (ORR). Festuca had a poor CIP, CRP, and ORR compared to other studied genera. Cynodon produced the highest shoot number per explant. Based on the results of the present study, MS medium supplemented with 60 mu M 2,4-D (for callus induction) and 7.5 mu M BA (for regeneration) can be used in multi-generic transformation studies with the genera used.