Development of Novel Interspecific Fertile Cytotype (4X) Of Pennisetum glaucum X Pennisetum purpureum Utilizing Modified Ploidy Coupled With Embryo Rescue Technique

Interspecific hybrids of genus Pennisetum (P. glaucum x P. purpureum) is the one of the most popular manmade hybrid. It combines the unique features of both P. glaucum (Pearl millet; Bajra) and P. purpureum (Napier; Elephant grass) species, which makes it more resilient to harsh environments with superior fodder quality. Due to ploidy level variation among the parents, these hybrids are sterile and propagated vegetatively only. To overcome this, attempts were made in the present study by exploring the feasibility of novel tetraploid pearl millet (2n=4x=28; Tetra 1; INGR 09047) developed at IGFRI, as a female parent in crossing program involving different Napier genotypes as male parent. Due to limited crossability and hybrid necrosis issues among countless crosses (> 1000), only 1% seed set was initially recorded that too in shriveled state and the developing embryos were aborted after 10-14 days of pollination and fertilization. To save these, embryo rescue technique was standardized and the developing embryos were dissected out aseptically and rescued after 8-10 days of pollination. Continuous crossing programme along with screening of large tissue culture raised nurseries resulted in development of a novel tetraploid seed producing BN hybrid (TBN-20-15) along with 14 novel sterile tetraploid BN hybrids. Presence of univalent chromosomes leads to sterility while proper pairing between parents of TBN-20-15 hybrid have significant effect on fertility. The fertile hybrid is able to produce >15,000-20,000 seeds throughout the year with 80-90% seed germination ability. Their hybridity was confirmed by morphology, molecular and cytogenetic studies. This fertile tetraploid BN hybrid (TBN-20-15) reported for the first time globally will be very helpful in easy and cost-effective dissemination of this highly potential forage crop to the farmer’s field. It has the potential to be the game changer in biofuel production, grassland rejuvenation programs besides bridging the fodder demand supply deficit.