Dihaploid induction in tetraploid durum wheat (Triticum durum L.) using pollen of Imperata cylindrica

Abstract

Doubled haploidy breeding protocols have revolutionized the varietal development programmes in bread wheat, however, the protocols have not proved much efficient in durum wheat. Presently, the durum wheat × maize system is being widely followed for haploid induction but the frequency of haploid development is very poor which has limited its application in durum wheat improvement programmes. In order to formulate an efficient wide hybridization-mediated approach for haploid induction in durum wheat, different genotypes of durum wheat were subjected to hybridization with Imperata cylindrica, a wild perennial grass for the first time in this laboratory. The investigation was carried out for two seasons. During the 1st year, the investigation was carried out on one genotype only, Langdon, in order to notice the development of haploid embryos and the factors that influence the haploid induction frequency. The most important factor influencing the embryo formation frequency was found to be the concentration of 2,4-dichlorophenoxyacetic acid (2,4-D). Upon pollinating the emasculated spikes of durum wheat genotypes, various concentrations of 2,4-D were injected into the uppermost internode of wheat culm for three consecutive days after pollination to find out the most responding concentration for haploid induction. During the next year, the protocol was applied to eight durum wheat genotypes. The frequency of haploid induction parameters varied with the durum wheat genotypes as well as 2,4-D concentration used. The mean pseudoseed and embryo formation frequency over all the genotypes ranged from 30.2 to 56.3% and 1.2 to 18.4%, respectively. The average embryo formation frequency over all the genotypes was found to be highest (18.4%) at 250 mg/l 2,4-D whereas it was superior for the genotypes WH 896 and Langdon over all the 2,4-D concentrations. At the most responding 2,4-D concentration (250 mg/l), the genotype A-9-30-1 exhibited the highest embryo formation frequency (32.1%). The ploidy status of the developed embryos was identified using cytological analysis carried out on the rootlets of the tissue culture generated plantlets.