A GENE FOR EMBRYO-ENDOSPERM COMPATIBILITY AND SEED VIABILITY IN ALLOPLASMIC TRITICUM-TURGIDUM

Alien cytoplasms have more deleterious effect on Triticum turgidum L. var. durum (2n = 28; 14 II; AABB) than on T. aestivum L. (2n = 42; 21 II; AABBDD). The species cytoplasm specific (scs) nuclear genes from the cytoplasm donor species and scs homoeoalleles ameliorate cytoplasmic effects in alloplasmic wheats. The D-genome chromosome(s) of T. aestivum must have a scs gene(s) that is absent in T. turgidum. Also, the dosage of scs homoeoalleles must be more favorable for nucleocytoplasmic compatibility (NCC) in 6x than 4x wheats. This paper reports that two genes, scs on 1DL telosome from T. aestivum 'Selkirk' and a vitality (Vi) gene from (Aegilops cylindrica) T. aestivum 'Selkirk', restored nucleocytoplasmic and embryo-endosperm compatibility, fertility, seed viability, and plant vigor in Ae. squarrosa and Ae. cylindrica 29-chromosome durum plants. In the absence of Vi, 29-chromosome plants set a few sporadic plump seed in selfed spikes but a few plump (about same number as in selfed spikes) and a large number of shrivelled seed in spikes crossed with euplasmic durum. Seed with Vi embryos were viable and those without Vi were nonviable. Similarly, Vi restored fertility to spontaneous aneuploids in the progeny of Ae. squarrosa 29-chromosome plants. Euploid sibs with Vi, but without IDL telosome, had greatly reduced vigor. The control 'Selkirk' and durum wheats did not have Vi. Hence, Vi may have originated by mutation in Ae. cylindrica 'Selkirk' or Ae. cylindrica durum. Similar spontaneous changes may improve fertility in interspecific hybrid progeny and condition complex inheritance of fertility restoration in alloplasmic wheats.