Non-transmissibility of the Y chromosome through the female line in androhermaphrodite plants of Melandrium album

Abstract

Androhermaphrodite plants of dioecious Melandrium album (syn. Silene latifolia), forming both bisexual and male flowers, were isolated from seeds treated with a hypomethylating drug, 5-azacytidine. These plants possessed the standard male karyotype (2n=24, XY), and the androhermaphrodite trait was inherited when these plants were self-pollinated or used as pollen donors. To determine whether or not their Y chromosome can be transmitted through the female line, an androhermaphrodite was crossed with an X-ray-induced hermaphrodite harbouring a large deletion on the Y chromosome, which makes it unable to pass through male or female meiosis. When this mutant hermaphrodite was pollinated with the androhermaphrodite, the seed progeny consisted of male, androhermaphrodite and female plants, whereas the reciprocal cross yielded female plants only. The genotypes of both parents and progeny were verified by karyological and restriction fragment length polymorphism (RFLP) analyses. The results show that the Y chromosome cannot pass through the female line, probably because of the absence of an X chromosome during embryo sac formation or an imbalance of X/Y chromosomes in developing endosperm.