NON-TRANSMISSIBILITY OF THE Y-CHROMOSOME THROUGH THE FEMALE LINE IN ANDROHERMAPHRODITE PLANTS OF MELANDRIUM-ALBUM

Androhermaphrodite plants of dioecious Melandrium album (syn. Silene l atifolia), 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 androher maphrodite trait was inherited when these plants were self-pollinated or used as pollen donors. To determine whether or not their Y chromoso me can be transmitted through the female line, an androhermaphrodite w as crossed with an X-ray-induced hermaphrodite harbouring a large dele tion on the Y chromosome, which makes it unable to pass through male o r female meiosis. When this mutant hermaphrodite was pollinated with t he androhermaphrodite, the seed progeny consisted of male, androhermap hrodite 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) an alyses. The results show that the Y chromosome cannot pass through the female line, probably because of the absence of an X chromosome durin g embryo sac formation or an imbalance of X/Y chromosomes in developin g endosperm.