Plant Breeding Institute, Maris Lane, CB2 2LQ, Trumpington, Cambridge, England.
Theor Appl Genet. 1987 Jan;73(3):403-9. doi: 10.1007/BF00262508.
Dominant alleles of the Kr1 and Kr2 genes reduce the crossability of hexaploid wheat with many alien species, including rye and Hordeum bulbosum, with Kr1 having the greater effect. However, a cytological study of wheat ovaries fixed 48 h after pollination showed that the wheat genotypes 'Highbury' (kr1, Kr2) and 'Chinese Spring (Hope 5B)' (kr1, kr2) were crossable with 'Seneca 60' maize, fertilization occurring in 14.4 and 30.7% of embryo sacs respectively. The latter figure was similar to the 29.7% fertilization found in 'Chinese Spring' (kr1, kr2). Most embryo sacs in which fertilization occurred contained an embryo but lacked an endosperm and where an endosperm was formed it was usually highly aberrant. All three wheat x maize combinations were karyotypically unstable and rapidly eliminated maize chromosomes to produce haploid wheat embryos.
Kr1 和 Kr2 基因的显性等位基因降低了六倍体小麦与许多异源物种（包括黑麦和珠芽大麦）的可杂交性，其中 Kr1 的影响更大。然而，对授粉后 48 小时固定的小麦卵巢的细胞学研究表明，小麦基因型“Highbury”（kr1、Kr2）和“Chinese Spring（Hope 5B）”（kr1、kr2）可与“Seneca 60”玉米杂交，分别有 14.4%和 30.7%的胚囊受精。后一个数字与“Chinese Spring”（kr1、kr2）中发现的 29.7%受精率相似。在发生受精的大多数胚囊中都含有一个胚胎，但缺乏胚乳，并且形成的胚乳通常高度异常。三种小麦 x 玉米组合均表现出染色体不稳定，迅速消除玉米染色体，产生单倍体小麦胚胎。
