Cytoplasmic Homology between <i>Aegilops squarrosa</i> L. and A. <i>cylindrica</i> Host.¹

Abstract

Fully fertile plants of normal vigor, normal chromosome number, and normal meiotic pairing resulted from substitution backcrosses involving autotetraploid Aegilops squarrosa L. (4x=28;DDDD) or A cylindrica Host. (2n=28;CCDD) as the females, and Triticum aestivum L. em Thell. as the recurrent male parent. However, the addition of a D‐genome chromosome to the T. durum Desf. nucleus was necessary to obtain alloplasmic T. durum with A. squarrosa or A. cylindrica cytoplasm. These 29‐chromosome plants had complete female fertility, but they produced a large proportion of shriveled, inviable seeds (or semilethal seedlings), and a few plump, viable seeds from crosses with euplasmic T. durum . They had sporadic partial seed set on selfed heads. Most of the plump seeds again produced 29‐chromosome plants. Apparently, shriveled, inviable seeds had 28‐chromosome zygotes. These nucleo‐cytoplasmic interactions indicate cytoplasmic homology between A. squarrosa and A. cylindrica .