Inheritance of disarticulation derived from some hexaploid brittle rachis wheat

Inheritance of disarticulation in progenies of hybrids among Tibetan weedra ce (9053 and AS907 of Triticum aestivum var. tibetanum), Yunnan hulled whea t (AS338 of T. aestivum concv. yunnanense) and spelt wheat (AS326 of T. aes tivum concv. spelta) was studied. Disarticulation type is governed by some disarticulation modifying genes. These modifying genes can be divided into two groups, that is, wedge modifying genes (Wm) and barrel modifying genes (Bm). The two kinds of genes are codominant. Wedge type disarticulation is governed by the complement of at least two dominant wedge modifying genes ( Wm(1) and Wm(2), Wm(3) and Wm(4), or Wm(5) and Wm). Barrel type disarticula tion is controlled by at least one dominant barrel modifying gene (Bm(1), B m(2) or Bm(3)) and its expression can be inhibited in certain genetic backg rounds. As to the background inhibition that dominant barrel modifying gene s cannot express in some homozygous brittle rachis wheat, the hypothesis of epistasy of many homozygous alleles was suggested.