Endosperm responses to irradiated pollen in apples

Abstract

The cytological effects of pollen γ-irradiation at 50 and 100 krad on both embryo and endosperm development were studied in Malus × domestica. Fruit and seed set were reduced by increasing doses of pollen irradiation, while embryo sacs resulting from the treatments differed in number and morphology of endosperm nuclei and in the presence or absence of an embryo. Nuclear abnormalities, distinguished from normal nuclear behaviour in embryo sacs derived from unirradiated pollen, included enhanced numbers of polyploid restitution nuclei, bridges between nuclei, excluded metaphase chromosome fragments and disrupted mitotic synchrony. Generally, a high dose of pollen irradiation (100 krad) generated an all-or-nothing response in the embryo sac, either creating highly abnormal embryos and/or endosperms which aborted, or showing relatively normal development. Callus produced from excised cellular endosperm differed in average genome size, that derived from 100 krad pollen being smaller than that from unirradiated pollen.

Pollination with gamma-irradiated pollen and development of fruits, seeds and parthenogenetic plants in apple

“…This finding, reported also by James et al . (1985) and studied later (Nicoll et al ., 1987), gives rise to an important question :…”

“…These results are obviously more favourable to the first hypothesis than the second one, at least for the endosperms derived from pollen irradiated by higher doses . If the maternal origin of these endosperms is confirmed, these homozygous diploid materials may have a potential utility in apple genetic study as well as breeding programmes (Nicoll et al ., 1987) .…”

“…Two experiments were carried out the study of overcoming self-incompatibility (Marin 1988and 1989respectively . Four genotypes were cucci et al ., 1984 and development of postfertilchosen as female parents : Erovan, Golden Deliization ovule (James et al ., 1985 ;Nicoll et al ., cious, X6677 (only for the 1988 experiment) and 1987) . In our preliminary experiment (Zhang et R1-49 (only for the 1989 experiment) .…”

Induced parthenogenesis in kiwifruit (Actinidia deliciosa) through the use of lethally irradiated pollen

“…At 0.5--0.1 kGy the embryo and endosperm degenerated after a few days. In a recent publication (Nicoll et al, 1987), 0.5 and 0.1 kGy irradiated pollen was used in crosses in apples. A high percentage of normal seeds were obtained at both doses, though germination ability and ploidy level were not determined.…”

Induced parthenogenesis by gamma-irradiated pollen in loquat for haploid production

“…Induction of maternal haploids embryos by pollination with irradiated pollen has been a effective method in different fruit species as apple (Nicoll et al 1987, Zhang and Lespinasse 1991), pear (Bouvier et al 1993, Inoue et al 2004), kiwifruit (Chalak and Legave 1997) and citrus (Aleza et al 2009, Froelicher et al 2007). In the case of loquat, haploidy induction via gynogenesis has not been described.…”