Wild Brassica Species Research Articles

Tiered tests to assess the environmental risk of fitness changes in hybrids between transgenic crops and wild relatives: the example of virus resistantBrassica napus

Over the last 20 years, there has been much research aimed at improving environmental risk assessment of transgenic crops. Despite large amounts of data, decisions to allow or prohibit the release of transgenic crops remain confused and controversial. We argue that part of the reason for confusion is the lack of clear definitions of components of the environment that should be protected, and, as a consequence, there is no way to judge the relevance of data collected under the auspices of 'environmental risk assessment'. Although this criticism applies to most aspects of environmental risk assessment of transgenic crops, it is most pertinent to effects that might result from an increase in plant fitness, often referred to as increased weediness. Environmental risk assessment of weediness is regarded as complicated: an increase in the fitness of a transgenic plant compared with non-transgenic counterparts will be the result of an interaction between the altered plant phenotype and an enormous number of environmental variables. This has led to the idea that risk assessment of weediness needs to "understand" these interactions, with the implication that exhaustive data are required. Here we argue that environmental risk assessment of the weediness of transgenic plants need not be complicated. Analysis of the conditions that must be met for increased weediness to occur suggests a series of studies that starts with simple tests in the laboratory under "worst case" assumptions, and becomes increasingly complex and realistic should the simpler studies not indicate negligible risk with sufficient certainty. We illustrate how the approach might work for assessing the risks of increased weediness using the example of possible introgression of a gene for Turnip mosaic virus (TuMV) resistance from oilseed rape to certain wild Brassica species.

Variation in resistance to the cabbage aphid ( Brevicoryne brassicae) between and within wild and cultivated Brassica species

Seven Brassica species were evaluated for their resistance to the cabbage aphid, Brevicoryne brassicae, in a series of field experiments. Four wild Brassica species, two 8 chromosome species with similarities to the B genome of Brassica nigra (Brassica fruticulosa and Brassica spinescens) and two 9 chromosome species containing the C genome (Brassica incana and Brassica villosa) were identified as possessing consistently high levels of antibiosis mediated resistance to B. brassicae. None of the species were shown to possess consistently high levels of antixenosis resistance. In more detailed glasshouse experiments one B-like genome species, B. fruticulosa, showed considerable variation between accessions collected from different sites for resistance to B. brassicae. In addition, individual accessions of one A genome species (Brassica rapa) and one C genome species (Brassica alboglabra) were shown to be highly variable in their resistance to B. brassicae, some plants of each accession being highly resistant and others very susceptible. The implications of the variability in resistance to B. brassicae within wild Brassica species for exploitation in Brassica breeding programmes are discussed.

SINE Insertions as Clade Markers for Wild Crucifer Species

Short interspersed nuclear elements (SINEs) are small noncoding transposable elements that are widespread in most eukaryotic genomes. Plant S1 SINEs are present in crucifers, especially in species of the Brassiceae tribe, and were generated by several waves of amplification of different evolutionary ages, suggesting that S1 insertional variability (presence/absence of an S1 at a given genomic site) could be used as a classification criterion to evaluate phylogenetic relationships. We applied this strategy on closely related species from the Brassica oleracea species complex using 21 independent S1 genomic sites. The microsatellite-like variation of S1 39 poly(A) tails was also used as a complementary classification criterion to obtain internal resolution in two different clades. The phylogenetic tree obtained by this approach is in general agreement with the classification made from chloroplast DNA restriction site polymorphisms and differs significantly from two other (nonequivalent) classifications made using nuclear restriction fragment length polymorphisms. Brassica incana, Brassica montana, and Brassica hilarionis are confirmed as the closest relatives of B. oleracea. From our data, we suggest that Brassica drepanensis emerged recently from a B. incana/Brassica villosa hybrid (with B. villosa as the maternal parent) following backcrosses to B. incana. We also detected several introgressions, confirming that these highly related species are capable of genetic exchange in their natural habitat. S1 markers are therefore very useful in understanding the detailed evolutionary history of wild Brassica species and could also be used to identify potential gene flow between cultivated (including transgenic) Brassica and their wild relatives.

Identification of high levels of resistance to cabbage root fly, Delia radicum, in wild Brassica species

Wild Brassica species and associated breeding lines were evaluated for their resistance to Delia radicum, the cabbage root fly, in the field in 1993 and in the field, glasshouse and laboratory in 1996. High levels of antibiosis resistance were discovered in the field in 1993 in Brassica fruticulosa, B. incana, B. villosa and B. spinescens and confirmed in the field in 1996 while two B. oleracea accessions and the susceptible control Brussels sprouts variety, ‘Oliver’, were highly susceptible. No D. radicum pupae were found in the soil around the roots of B. fruticulosa and B. spinescens at the end of the season. All the Brassica species were attractive to egg-laying by D. radicum in the field and in a laboratory experiment and therefore lacked antixenosis resistance. In a series of glasshouse experiments, Brassica species and breeding lines were inoculated with D. radicum eggs supplied from a laboratory culture and the effects of larval feeding on plants recorded. Brassica incana, B. fruticulosa and B. spinescens were highly resistant, most plants surviving, whilst B. macrocarpa and B. villosa were moderately resistant as were two F1 lines bred from a cross between B. macrocarpa and B. oleracea.

Relationships of wildBrassicaspecies with chromosome number 2n= 18, based on comparison of the DNA sequence of the chloroplast intergenic region betweentrnL(UAA) andtrnF(GAA)

A specific chloroplast DNA sequence was compared in 34 populations representing 10 wildBrassica species (2n = 18). Species studied were Brassica bourgeaui (Webb) O. Kuntze, Brassica cretica Lam., Brassica hilarionis G.E. Post, Brassica incana Ten., Brassica insularis Moris, Brassica macrocarpa Guss., Brassica montana Pourret, Brassica oleracea L., Brassica rupestris Raf., and Brassica villosa Biv. The sequence was located between the trnL and trnF genes in the large, single-copy region of the chloroplast genome. Site-specific primers were used to amplify the region via the polymerase chain reaction technique. Products of the same size were amplified from all populations. Sequence differences in the DNA fragments were detected by denaturing gradient gel electrophoresis. Ten different haplotypes defined by 20-base sequence differences were detected. Haplotype did not always reflect species classification. Haplotypes were shared by the species pairs B. rupestris - B. villosa, B. cretica - B. incana, and B. bourgeaui - B. oleracea. Populations carrying divergent haplotypes were discovered for B. cretica, B. montana, and B. insularis. Possible introgression of the B. macrocarpa cytoplasm into a B. insularis population was observed. DNA sequences for the 10 haplotypes were determined and subjected to phylogenetic analysis using maximum parsimony. In the phylogenetic tree, the B. rupestris - B. villosa haplotype formed a basal clade, the B. macrocarpa haplotype diverged next, while all other species fell into a third clade.Key words: wild Brassica species, B. oleracea cytodeme, haplotype, cpDNA, phylogeny.

The relative importance of glucosinolates and amino acids to the development of two aphid pests Brevicoryne brassicae and Myzus persicae on wild and cultivated brassica species

AbstractThis paper describes an experiment to investigate the relative importance of glucosinolates and the availability of free amino acids in the phloem to the feeding behaviour and development of the specialist brassica aphid, Brevicoryne brassicae (L) (cabbage aphid) and the generalist, Myzus persicae, (Sultzer) (peach potato aphid). Aphid development was determined on brassica species and cultivated brassica varieties. Analysis of individual glucosinolates in the wild brassica species identified significant differences in their profiles and in their concentrations present in freeze dried leaves. Multiple regression analysis showed a significant correlation (r = 0.83) between the intrinsic rate of increase of B. brassicae and glucosinolate concentrations; four glucosinolates, 2‐OH‐3‐butenyl, and 2‐propenylglucosinolate, 3‐methoxyindolyl and 4‐pentenylglucosinolates accounted for 79% of the variation. The intrinsic rate of increase of M. persicae was less correlated, though still significant (r = 0.5); 3‐indolyglucosinolate and 3‐butenylglucosinolate accounted for 47% of the variation. Regression analysis also showed a correlation between phloem amino acid concentrations and the intrinsic rate of increase of B. brassicae (r = 0.48) but not of M. persicae. The concentration of the important amino acids tyrosine, alanine, leucine and glutamic acid, accounted for 43% of the variation in intrinsic rate of increase. Leaf water potential of the Brassica species showed no relationship with the intrinsic rate of increase of either B. brassicae or M. persicae.

Relationships of wild Brassica species with chromosome number 2n = 18, based on RFLP studies

An array of 10 wild Brassica species with chromosome number 2n = 18 represented by 34 populations was analyzed for genome similarity using genomic and cDNA clones. Species studied included B. bourgeaui (Webb) O. Kuntze, B. cretica Lam., B. hilarionis G.E. Post, B. incana Ten., B. insularis Moris, B. macrocarpa (Guss.) Caruel, B. montana Pourret, B. oleracea L., B. rupestris Rafin., and B. villosa Biv. The RFLP data were used to calculate similarities between populations that were subsequently treated in a cluster analysis. Most populations of a species were grouped together and were separate from populations of other species. The previously identified B. incana - B. rupestris - B. villosa complex was verified, and genetic similarity between the species B. montana and B. oleracea was evident. An interesting association between B. insularis and B. macrocarpa was observed. The UPGMA analysis showed that the species tended to cluster according to geographic region: B. cretica and B. hilarionis comprise a cluster that could be called Eastern Mediterranean; B. oleracea, B. bourgeaui, and B. montana define an Atlantic - Western Mediterranean cluster; B. incana, B. rupestris, and B. villosa form an Italian group; and a B. insularis - B. macrocarpa association may be called Central Mediterranean.

The Ecology of Agricultural Pests: Biochemical Approaches.

Introduction. Biochemical systematics: principles and perspectives for pest management. Combined use of biochemical, immunological and molecular assays for infection, species identification and and resistance detection in field populations of Anopheles (Diptera: Culicidae). Studies of interactions between alfalfa weevil strains, Wolbachia endosymbionts and parasitoids. Biochemical approaches to the study of ecological genetics: the role of selection and gene flow in the evolution of insecticide resistance. A molecular and ecological investigation of the large arionid slugs of north west Europe: the potential for new pests. Systematics of brown planthopper and related species using nuclear and mitochondrial DNA. Application of novel molecular markers (DNA) in agricultural entomology. Location of resistance to Brevicoryne brassicae in wild brassica species. The use of DNA markers in population genetics and ecological studies of the desert locust Schistocerca gregaria (Orthoptera: Acrididae). The use of DNA analysis and the polymerase chain reaction in the study of introduced pests in New Zealand. Serological analysis of arthropod predation: past, present and future. Serological diagnosis of parasitism: a monoclonal antibody-based immunodot assay for Microplitis (Hymenoptera: Braconidae). Polyclonal, monoclonal and engineered antibodies to investigate the role of predation in slug population dynamics. The potential of combinatorial antibody libraries in pest/predator relationship studies. Serological analysis of predators of Helicoverpa armigera Hubner (Lepidoptera: Noctuidae) eggs if sorghum-pigeonpea intercropping at ICRISAT, India: a preliminary field study. Using gut content immunoassays to evaluate predaceous biological control agents: a case study. An environmental risk assessment for release of an exotic microsporidium for European corn borer control in North America. Progress in quantifying predation using antibody techniques. Electrophoretic approaches to predator-prey interactions. Genetics of esterases in laboratory and feral cotton boll weevils, Anthonomus grandis Bohemia. Practical applications for techniques to determine the nutritional state and age of field caught tsetse flies.

Effect of Brassica oxyrrhina Cytoplasm on Raphanus sativus.

Brassica属の野生種の一つであるBrassica oxyrrhina Coss.(2n=18)を種子親,ダイコン(Raphanus sativus L. 2n=18)を花粉親にした交雑後代より作出した複二倍体(2n=36)にダイコンを連続戻し交配した。その結果,B2世代においてB.oxyrrhina細胞質を持つ2n=18の個体を作出した。核置換が進行しても花粉稔性の回復はあまり見られず,B.oxyrrhina細胞質はダイコンの花粉の授精髭カを抑制させる効果があることが分かった。また,核置換の進行とともに種子稔性も上昇したが,その程度は良好ではなかった。B.oxyrrhina細胞質を持つダイコン9系統とそれぞれの反復親である9栽培種との間で正逆交雑を行い,得た両F1植物の種子稔性,花粉稔性,生育,形態などを調査した。その結果,B.oxyrrhina細胞質を持つダイコンにおけるクロロフィル欠乏はまったく見られなかった。根長,根径,根重,葉重について見ると,赤丸二十日,聖護院,四十日,宮重において,B.oxyrrhina細胞質がダイコンの生育に影響を及ぼしていたが,Raddike ostergruss,練馬においては影響は見られなかった。したがって,B.oxyrrhina細胞質と不調和を起こさない核遺伝子が存在する可能性があり,このような核遺伝子を導入することにより生育阻害の問題は解消できると考えられる。B.oxyrrhina細胞質を雄性不稔細胞質として利用することに関しては,50%以下の花粉稔性では種子ができないこと,また,充分な花粉稔性を持ったものでも授精髭カを持っていない個体もあり,実用的に利用できる可能性もあると考えられる。

Phylogenetic relationships between the wild taxa of the Brassica oleracea L. group (2 n = 18) using random amplified polymorphic DNA assay

The aim of this study was to help establish the phylogenetic relationships between the wild taxa of the Brassica oleracea complex using a random amplified polymorphic DNA (RAPD) assay and also to test the potential use of RAPDs in discriminating among closely related species. A total of 22 populations belonging to 15 taxa were analysed; 20 arbitrary primers were studied and six were selected for the detection of 129 reproducible polymorphic fragments, ranging from 200 to 2400 base pairs. These genetic markers, which allowed us to distinguish the different taxa, were used to study the phylogenetic and evolutive relationships of the wild Brassica ( n = 9) species. The dendrogram obtained reflects the already accepted genetic relationships among the 15 taxa. Three clearly separated branches are shown: the Western group, the Sicilian group and the Aegean group. The maximum diversity is detected in the Aegean group and the highest similarity coefficient is shown by the Sicilian group, results which are consistent with previous phytochemical analyses.

Genetic validity of RAPD markers at the intra- and inter-specific level in wild Brassica species with n=9

The sequence homology of co-migrating RAPD markers within a genus, across species, and among populations of a species was investigated. DNA was isolated from ten wild Brassica species with n=9 and the RAPD patterns were established using three random primers. Five RAPD markers which appeared to be characteristic for the n=9 species (genus level), four markers which appeared to be species specific, and one population-specific marker were isolated from agarose gels and hybridized to the RAPD profiles of the ten Brassica species. Two RAPD markers were cloned for comparison with gel-isolated RAPD fragment probes in hybridization experiments. Non-specific and background hybridization, occurring when gel-isolated fragments were used as probes, disappeared when cloned fragments were used. A total of 250 RAPD-marker hybridizations were scored according to visual presence or absence in a gel lane. All except three markers hybridized as expected, resulting in an error rate of 1.2%. The deviating results included a lack of hybridization although a band was visible in the gel, a length polymorphism for one marker, and a dual hybridization signal for two single-band markers.

Genetic validity of RAPD markers at the intra- and inter-specific level in wild Brassica species with n=9

Genetic validity of RAPD markers at the intra- and inter-specific level in wild Brassica species with n=9

Isolation of a chitin‐binding lectin, with insecticidal activity in chemically‐defined synthetic diets, from two wild brassica species with resistance to cabbage aphid Brevicoryne brassicae

AbstractA lectin, with a chitin‐binding domain and chitinase activity, is present in significant quantities in the wild brassica species B. fruticulosa and B. spinescens but at low levels in cultivated cabbage cv. Offenham Compacta. The lectin, purified > 1000 fold after binding to chitin, migrated on SDS ‐ PAGE gels as a single band with a Mr of 14.500. The amino acid composition of the lectin from B. spinescens indicated high concentrations of asparagine/aspartic acid, glycine, leucine and serine in common with other chitin‐binding lectins with insecticidal and antifungal activities. Brassica lectin and the closely related agglutinin from wheatgerm and nettle show significant insecticidal activity when presented to Brevicoryne brassicae in chemically‐defined synthetic diets.

A chemosystematic survey on wild relatives of Brassica oleracea L.

AGUINAGALDE, I., GOMEZ-CAMPO, C. & SANCHEZ-YELAMO, M. D., 1992. A chemosystematic survey on wild relatives of Brassica oleracea L. A study on 12 taxa of n= 9, wild Brassica species (including wild B. oleracea) has led to the detection of 21 different flavonol-glycosides. Differential patterns have been obtained for each taxon. Seed proteins and five isoenzyme systems have been analysed by polyacrylamide gel electrophoresis. The presence of many bands common to ail species was the rule for seed proteins, but differences in polypeptide contents were observed. There were also clear qualitative differences in isoenzyme patterns. Interspecific differences were examined by including those phytochemical characters in a numerical analysis. While the maximum morphological variability occurs in Sicily, phytochemical diversity seems to be maximum further east, in the B. cretica group.

Seed glucosinolates of fourteen wild Brassica species

Seed glucosinolates have been determined for 14 wild Brassica species, by micro-scale GC analysis of silylated derivatives. Of these, 12 were investigated for the first time. The majority of taxa exhibited high alkenylglucosinolate levels, although prop-2-enylglucosinolate appears to be generally absent. Other known methionine-derived glucosinolates predominate in B. tournefortii, B. elongata and B. deflexa. Phenylalanine-derived 4-hydroxybenzylglucosinolate is characteristic of section Brassicaria plants and represents the first finding of this glucosinolate in authenticated Brassica material.