期刊
ANNALS OF BOTANY
卷 89, 期 2, 页码 165-170出版社
OXFORD UNIV PRESS
DOI: 10.1093/aob/mcf024
关键词
apomixis; Paspalum notatum; pollination timing; RAPID fingerprinting
Progeny tests employing molecular markers allow the identification of individuals originated by sexual means among the offspring of a facultative apomict. The objective of this work was to evaluate the effect of the pollination timing on the proportion of sexually formed individuals in progenies of a facultative apomictic Paspalum notation genotype. Progeny families of approx. 30 plants each were generated at five different pollination times: 1-3 d pre-anthesis; at anthesis; and 2, 4 and 6 d post-anthesis. Cytoembryological analyses indicated that approx. 17 % of the ovules carried a meiotic cytologically reduced embryo sac in florets formed simultaneously with those used for crosses. The parental plants and the five F-1 families were analysed using RAPD molecular markers. Ninety-five oligonucleotides were assayed on the progenitors in order to search for male-specific bands. Eight primers presenting clear polymorphic bands were selected for use in the progeny tests. The proportion of sexually produced progeny reached 3.4 % before anthesis and 20 % at anthesis, while pollination after anthesis generated only maternal plants. A second progeny of 97 plants obtained from pollination at anthesis produced 16 off-type plants (16.5 %), of which only one was a B-III hybrid (2n + n). Our results indicate that pollination at anthesis allows the greatest potential for sexuality to be expressed in this facultative apomictic genotype. When pollination is delayed as soon as 2 d after anthesis, only the aposporous sacs develop endosperm through pseudogamy to set seed. (C) 2002 Annals of Botany Company.
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