Critical Discussion on Abortive Interspecific Crosses in <i>Brassica</i>

Nishiyama, Ichizo; Sarashima, M.; Matsuzawa, Yasuo

doi:10.1111/j.1439-0523.1991.tb00552.x

Cited by 43 publications

(23 citation statements)

References 37 publications

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“…The lower number of seeds per pod on maternal plants and the lower proportional seed development from Br(female) Bn(male) crosses than from the reciprocal crosses are in accordance with results from several other studies (seed number: reviewed by Nishiyama et al, 1991 andScheffler &Dale, 1994;proportional seed development: Röbbelen, 1966). They also match the common observation that hybridization and seed-set are more successful when the parent of the higher ploidy level (here B. napus) serves as the seed parent, and when an allodiploid (B. napus) is pollinated by its diploid progenitor (Stebbins, 1958).…”

Section: Fitness Componentssupporting

confidence: 90%

Fitness of F1 hybrids between weedy Brassica rapa and oilseed rape (B. napus)

1998

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As part of an ongoing study of the hybridization biology of cultivated oilseed rape (Brassica napus) and weedy B. rapa, we studied the fitness of hybrids between three weedy B. rapa populations and three varieties of B. napus. Reciprocal pollinations were performed, and the resulting offspring were scored for seed development, survival in the field, pod-and seed-set. Seeds from heterospecific crosses developed within pods in lower proportions than seeds from conspecific crosses. Hybrid offspring survived in the field as frequently as conspecific offspring, and produced many more pods that contained fewer seeds. Combining the fitness components into a multiplicative estimate, we found the hybrids to be intermediate to their parents, and significantly more fit than B. rapa. Significant genotypic differences were detected between offspring produced by different parental plants, populations and varieties for some of the fitness components scored. Our results on hybrid fitness are discussed with respect to the possibility that transgenes in oilseed rape may introgress spontaneously into weedy B. rapa.

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Section: Fitness Componentssupporting

confidence: 90%

Fitness of F1 hybrids between weedy Brassica rapa and oilseed rape (B. napus)

1998

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“…If it is assumed that the EBN values for both S. alba 2x and 4x and B. napus are different, the observed reciprocal differences and the difference between the crossability of S. alba 2x and S. alba 4x may be explained by their EBN ratios. However, the contradictory results of our work and those of others (Ch~vre et al, 1991;Heyn, 1977) indicate that the outcome of these intergeneric crosses can only in part be explained by the EBN theory or the PNA (polar-nuclei activation) hypothesis (Nishiyama et al, 1991). Other mechanisms (e.g.…”

Section: Discussioncontrasting

confidence: 50%

Studies of pollen grain germination, pollen tube growth, micropylar penetration and seed set in intraspecific and intergeneric crosses within three Cruciferae species

Lelivelt¹

1993

Euphytica

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Pollen grain germination, pollen tube growth and micropylar penetration were investigated in intraspecific and intergeneric crosses involving Brassica napus L. ssp. oleifera (Metzg.) Sinsk. (oil-seed rape or fodder rape), xBrassicoraphanus Sageret (Raparadish) and diploid (2x) and tetraploid (4x) accessions of Sinapis alba L. (white mustard). For the reciprocal intergeneric crosses between B. napus and xBrassicoraphanus no effective barriers to pollen tube growth on stigmata or in styles were observed. The resulting low frequency of hybrid plants was mainly associated with a low rate of ovules with micropylar penetration per siliqua or with embryo abortion. Hybrid plants could be obtained without use of embryo rescue. In reciprocal crosses between B. napus and S. alba 2x or 4x incongruity barriers were observed on the stigma, in the style, and in the ovary resulting in a low frequency of ovules with micropylar penetration per siliqua. Open flower-pollination compared to bud-pollination generally was the more favourable procedure for pollen grain germination and pollen tube growth in crosses involving S. alba, but for micropylar penetration and seed set no differences were observed. Crosses between S. alba 2x ( 9 ) and B. napus (~) were found to result in a higher frequency of ovules with micropylar penetration as compared to reciprocal crosses or crosses with S. alba 4x. All reciprocal crosses between B. napus and S. alba 2x or 4x were unsuccessful when no embryo rescue was applied. Embryo rescue shortly after pollination, i.e. 2 to 5 days, however, resulted in hybrid seeds and plants, but only when applied to crosses between S. alba 2x ( 9 ) and B. napus ((;). The possible effects of the genome constitution, taxonomic distance and the parthenogenetic and parthenogenesis inducing ability of the parental genotypes on the observed malfunctions at the pre-and/or post-zygotic stage of the pollen grain-pistil interactions are discussed.

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“…When one of the parents was diploid, progeny were often obtained only when B. napus was used as the female parent in the backcross. Because of this unilateral incompatibility, which has been reported for both the initial interspecific hybridization and subsequent generations, flow of genes is most likely to be from related species into B. napus, and not the reverse (Nishiyama et al, 1991).…”

Section: Resultsmentioning

confidence: 95%

Opportunities for gene transfer from transgenic oilseed rape (Brassica napus) to related species

Scheffler

Dale

1994

Transgenic Research

169

114

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Before novel transgenic plant genotypes are grown outside containment facilities and evaluated under field conditions, it is necessary to complete a risk assessment to consider the possible consequences of that release. An important aspect of risk assessment is to consider the likelihood and consequences of the transgene being transferred by cross-pollination to related species, including other crops, weeds and ruderal populations. The purpose of this report is to review the literature to assess the ease with which Brassica napus can hybridize with related species. The evidence for hybridization is considered at three levels: a) by open pollination, b) by hand pollination and c) by the use of in vitro ovule and embryo rescue techniques; and also examines the fertility and vigour of the F 1, F 2 and backcross generations. Four species are reported to hybridize with B. napus by open pollination: B. rapa and B. juncea using fully fertile parents; and B. adpressa and R. raphanistrurn using a male-sterile B. napus parent. Seventeen species are reported to form hybrids (including the four species above) with B. napus when pollination is carried out manually. At least 12 of these species were unable to form F 2 progeny, and eight were unable to produce progeny when the Fa was backcrossed to one of the parental species. Many factors will influence the success of hybridization under field conditions, including: distance between the parents, synchrony of flowering, method of pollen spread, specific parental genotypes used, direction of the cross and the environmental conditions. Even where there is a possibility of hybridization between B. napus and a related species growing in the vicinity of a release, poor vigour and high sterility in the hybrids will generally mean that hybrids and their progeny will not survive in either an agricultural or natural habitat.

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Critical Discussion on Abortive Interspecific Crosses in Brassica

Cited by 43 publications

References 37 publications

Fitness of F1 hybrids between weedy Brassica rapa and oilseed rape (B. napus)

Fitness of F1 hybrids between weedy Brassica rapa and oilseed rape (B. napus)

Studies of pollen grain germination, pollen tube growth, micropylar penetration and seed set in intraspecific and intergeneric crosses within three Cruciferae species

Opportunities for gene transfer from transgenic oilseed rape (Brassica napus) to related species

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