Lipow S R, Wyatt R
Department of Botany, University of Georgia, Athens, Georgia 30602, USA.
Genetics. 2000 Feb;154(2):893-907. doi: 10.1093/genetics/154.2.893.
Most individuals of Asclepias exaltata are self-sterile, but all plants lack prezygotic barriers to self-fertilization. To determine whether postzygotic rejection of self-fertilized ovules is due to late-acting self-incompatibility or to extreme, early acting inbreeding depression, we performed three diallel crosses among self-sterile plants related as full-sibs. The full-sibs segregated into four compatibility classes, suggesting that late acting self-incompatibility is controlled by a single gene (S-locus). Crosses between plants sharing one or both alleles at the S-locus are incompatible. An additional diallel cross was done among full-sib progeny from a cross of a self-sterile and a self-fertile plant. These progeny grouped into two compatibility classes, and plants within classes displayed varying levels of self-fertility. This suggests that the occasional self-fertility documented in natural pollinations is caused by pseudo-self-fertility alleles that alter the functioning of the S-locus.
大多数高根马利筋个体是自交不育的，但所有植株都缺乏阻止自花受精的合子前障碍。为了确定自花受精胚珠的合子后排斥是由于迟效自交不亲和性还是由于极端的、早效的近交衰退，我们在作为全同胞相关的自交不育植株间进行了三次双列杂交。全同胞分为四个亲和性类别，这表明迟效自交不亲和性由单个基因（S位点）控制。在S位点共享一个或两个等位基因的植株间杂交是不亲和的。在一株自交不育植株和一株自交可育植株杂交产生的全同胞后代间进行了另外一次双列杂交。这些后代分为两个亲和性类别，类内植株表现出不同程度的自交可育性。这表明在自然授粉中记录到的偶尔的自交可育性是由改变S位点功能的假自交可育等位基因引起的。
