Pistillody, homeotic transformation of stamens into pistil-like structures, in alloplasmic wheat is associated with alterations to expression pattern of floral organ identity genes

Abstract

Pistillody has been reported in the cytoplasmic substitution (alloplasmic) lines of common wheat (Triticum aestivum) with Aegilops crassa cytoplasm. The induction of pistillody is suppressed by the Rfd1 gene located on the long arm of chromosome 7B (7BL) in wheat cultivar Chinese Spring (CS). Because of the absence of Rfd1, the alloplasmic line of CS ditelosomic 7BS ((cr)-CSdt7BS) without 7BL exhibits pistillody, whereas the euplasmic CS ditelosomic 7BS (CSdt7BS) having normal cytoplasm forms normal stamens. The class B MADS box genes, WPI (Wheat PISTILLATA) and WAP3 (Wheat APETALA3), were expressed in the normal stamen primordia of CSdt7BS, but not in the pistil-like stamen primordia of (cr)-CSdt7BS. On the other hand, a YABBY gene, TaDL, was expressed in the pistil-like stamen primordia of (cr)-CSdt7BS. The results indicate that the pistillody in the alloplasmi wheat is associated with alterations to expression pattern of floral organ identity genes.