Photoperiod-sensitive cytoplasmic male sterility in alloplasmic wheat with Ae. crassa cytoplasm. Genetic characteristics of nuclear and cytoplasmic types and floral organ morphology without the lemma in the alloplasmic lines are schematically represented. (A) (cr)-CS has normal stamens because of the fertility restorer gene Rfd1 against the Ae. crassa cytoplasm on the long arm of chromosome 7B. (B) (cr)-CS monotelodisomic 7BS, which has Rfd1 in a hemizygous state, shows partial pistillody (arrow) and reduced female fertility. (C) (cr)-CS ditelosomic 7BS, which lacks both of the long arms pair of chromosome 7B and therefore lacks Rfd1, shows complete pistillody and female sterility, independent of day length. Floral organ morphology of CS ditelosomic 7BS was indistinguishable from that of CS. (D) Euplasmic CS. (E) (cr)-N26 shows homeotic transformation of stamens into pistils (pistillody) only under long-day conditions. (F) (cr)-N26 occasionally shows partial pistillody (arrow) and reduced female fertility under short-day conditions. (G) An EMS-induced mutant of (cr)-N26 shows normal floral phenotype . This mutant fails to measure day length. (H) (cr)-N61, which contains multiple loci for Rfd genes, shows normal floral phenotype. Pa, palea; P, pistil; S, stamen; L, lodicule; pTs, partially transformed stamen; Ts, transformed stamen.