Regeneration and somaclonal variation in apomictic Paspalum dilatatum Poir

Summary In an attempt to incorporate variation into a uniform obligate apomict, plants of apomictic common dallisgrass, Paspalum dilatatum Poir., were regenerated from callus derived from immature inflorescences. Plants developed through both organogenesis and embryogenesis. A total of 682 regenerants were produced and more than 400 were transplanted into a field nursery and screened for somaclonal variation. Eventually 20 regenerants were selected, increased, and planted into a replicated nursery along with normal common dallisgrass. The characteristics examined were maturity date, plant height, number of racemes per inflorescence, number of spikelets per raceme, pubescence, stigma and anther color, ergot resistance, seed germination, seed set, pollen stainability, method of reproduction, and chromosome number. There were differences among the regenerants and between them and common dallisgrass for all traits except chromosome number, stigma and anther color, and ergot resistance. One of the more important regenerants had significantly higher seed set than common dallisgrass. All regenerants reproduced by aposporous apomixis but some exhibited a high degree of abortion while others had more aposporous embryo sacs per ovule than common dallisgrass. These findings demonstrate that common dallisgrass can be regenerated through tissue culture and that somaclonal variation is expressed in some of the regenerants, even though some of the altered traits are deleterious.