P. du Jardin

Use of chloroplast DNA polymorphisms for the phylogenetic study of seven Phaseolus taxa including P. vulgaris and P. coccineus.

The genetic variability of seven Phaseolus taxa has been evaluated on the basis of molecular data and the results have used to clarify the phyletic relationships between several taxa of the P. coccineus L. complex. Chloroplast DNA (cpDNA) from 33 populations was digested with six restriction endonucleases, revealing some polymorphisms that made it possible to divide most of the taxa into two main groups: the subspecies of P. coccineus on the one hand, and P. vulgaris L., P. polyanthus Greenman and P. costaricensis (Freytag and Debouck) on the other hand. P. polyanthus is closer to P. vulgaris than the other taxa of the second group and should be considered as a separate species. The position of the wild species P. costaricensis is intermediate between P. coccineus and P. polyanthus. P. glabellus shows sufficient polymorphisms at the cpDNA level to be recognized as a separate species, as previously suggested from total seed-protein electrophoretic studies. These results favour the hypothesis of a common phylogeny for P. vulgaris, P. polyanthus, P. costaricensis and P. coccineus from a single wild ancestor. Although cpDNA is generally known to be uniform at the intraspecific level, some additional polymorphisms were also detected within P. vulgaris, P. polyanthus and P. coccineus. Further studies are required to understand the significance of the latter.

Molecular evidence for an Andean origin and a secondary gene pool for the Lima bean ( Phaseolus lunatus L.) using chloroplast DNA

Abstract Chloroplast DNA (cpDNA) diversity has been examined using PCR-RFLP and RFLP strategies for phylogenetic studies in the genus Phaseolus. Twenty-two species, including 4 of the 5 cultivated species (P. lunatus L., the Lima bean; P. vulgaris L., the common bean; P. coccineus L., the runner bean and P. polyanthus Greenman, the year-bean), represented by 86 accessions were included in the study. Six PCR primers designed from cpDNA and a total cpDNA probe were used for generating markers. Phylogenetic reconstruction using both Wagner parsimony and the neighbor-joining method was applied to the restriction fragment data obtained from each of the molecular approaches. P. vulgaris L. was shown to separate with several species of largely Mesoamerican distribution, including P. coccineus L. and P. polyanthus Greenman, whereas P. lunatus L. forms a complex with 3 Andean species (P. pachyrrhizoides Harms, P. augusti Harms and P. bolivianus Piper) co-evolving with a set of companion species with a Mesoamerican distribution. Andean forms of the Lima bean are found to be more closely related to the 3 Andean wild species than its Mesoamerican forms. An Andean origin of the Lima bean and a double derivative process during the evolution of P. lunatus are suggested. The 3 Andean species are proposed to constitute the secondary gene pool of P. lunatus, while its companion allies of Mesoamerican distribution can be considered as members of its tertiary gene pool. On the basis of these data, an overview on the evolution of the genus Phaseolus is also discussed.

Breeding for "low-gossypol seed and high-gossypol plants" in upland cotton. Analysis of tri-species hybrids and backcross progenies using AFLPs and mapped RFLPs.

Abstract This work aims at breeding upland cotton [Gossypium hirsutum L., 2(AD)1 genome] with a reduced level of gossypol in the seeds for optimal food and feed uses, and a high gossypol level in the remaining organs for resistance to pests. Two tri-species Gossypium hybrids, (G. thurberi–G. sturtianum–G. hirsutum and G. hirsutum–G. raimondii–G. sturtianum) including G. sturtianum (2C1) as a donor, G. thurberi (2D1) and G. raimondii (2D5) as a bridge species, were created. Recurrent selection initiated with these tri-species hybrids produced backcross (BC) progenies expressing the ”low-gossypol seed and high-gossypol plant” trait at different levels. We used AFLP markers to assess the genetic similarity among the germplasm and RFLP probes to tag the introgression of specific chomosome segments from the parental species. Five pairs of AFLP primers generated 477 fragments, among which 417 (87.4%) were polymorphic. The genetic similarity between the upland cotton and the wild species ranged from 29.5 to 43.2%, while similarity reached 80% between upland cotton and BC3 plants. Introgression of species-specific AFLPs was evident from all the parental species and confirmed the hybrid origin of the analyzed progenies. Southern-blot analysis based on 49 RFLP probes allowed us to trace the introgression of parental DNA segments in the tri-species hybrids and in three generations of backcross. Introgression was evident from 11, 8 and 7 linkage groups of G. sturtianum, G. raimondii and G. thurberi respectively. The types of introgression revealed by RFLP probes are discussed, and breeding schemes to enhance recombination are proposed. The ability to trace DNA segments of known chromosomal locations from the donor G. sturtianum through segregating generations is a starting point to map the ”low-gossypol seed and high-gossypol plant” traits.

Distinction between cultivated and wild chicory gene pools using AFLP markers

Abstract. The cultivation area of industrial chicory, Cichorium intybus L. cv Sativum, coincides with the natural distribution area of its wild relative, C. intybus L., which could lead to gene flow between wild and cultivated types. The genetic diversity within and between the two types has therefore been studied using AFLP genotyping of samples from 12 wild populations collected in Belgium and ten commercial varieties. The genotyping of 233 individuals allowed the identification of 254 AFLP markers. Similar levels of genetic diversity were observed within wild populations and cultivated varieties, suggesting the absence of any strong bottleneck in the history of the cultivated types. The phylogenetic analysis pointed to a monophyletic origin of cultivated varieties as compared to the local wild populations studied, hence the two types of chicory form two separate gene pools. The genotyping of some individuals sampled in ruderal sites clearly showed that they belong to the cultivated gene pool, which suggests the existence of feral or weedy types. The low differentiation observed among wild populations indicates that gene flow might be important in this species.

Use Of Random Cdna Probes To Detect Restriction-Fragment-Length-Polymorphisms Among Apple Clones

Abstract The existence and usefulness of restriction fragment length polymorphisms (RFLPs) among apple clones were investigated. A cDNA library of micropropagated McIntosh cultivar ‘Wijcik’ plantlets was constructed in the vector λ gt 11 and used as a source of random probes to identify RFLPs. One probe, pCW-1, which revealed a high level of intercultivar polymorphisms, was selected. This probe, in combination with three restriction enzymes, was used to distinguish by Southern blotting 10 cultivars and rootstocks from each other. Moreover, inheritance of the RFLPs detected by this probe was observed.

Homologies to plastid DNA in the nuclear and mitochondrial genomes of potato

SummaryPotato plastid DNA clones, representing onefourth of the potato plastome complexity and containing sequences of the 16SrRNA, rps16, atpA, atpE, psaA, psaB, trnK, trnV, and trnG genes, were used as hybridization probes on nuclear- and mitochondrial-enriched DNAs. Each probe hybridized to multiple nuclear restriction fragments distinct from the plastid cleavage products generated by the same endonucleases. The nuclear hybridizable fragments are highly methylated at their Hpall target sequences (C/CGG). In some instances, the transfer seemed to involve plastid regions of several kilobase pairs, as reflected by the co-integration in the nucleus of restriction sites that are distant in the plastome. Three clones hybridized additionally to distinct mitochondrial fragments. These results indicate that extensive DNA transfers did occur between plastids and other organelles in potato.

Identification Of Mitochondrial Plasmid Like Dnas In Picea Abies (L.) Karst.

Abstract The Norway spruce (Picea abies (L.) Karst.) mitochondrial DNA has been extracted from embryonal suspensor masses. In addition to a master chromosome, a family of plasmid-like DNAs were identified. These latter shared cross homologies but had no evident sequence homology with the master chromosome. The occurrence of mitochondrial plasmid-like DNAs was investigated in trees from different provenances. A vast majority of trees displayed extrachromosomal DNA elements of variable stoechiometry. For some trees, the sequences homologous to the extrachromosomal DNA elements were found associated with high molecular weight DNA.

Potato tubers exhibit both homolytic and heterolytic hydroperoxide fatty acid-cleaving activities.

The action of a crude potato-tuber extract on 9- and 13-hydroperoxides of linoleic and linolenic acids was investigated. HPLC analysis revealed that 50% of the 9-hydroperoxide isomers and almost all the 13-hydroperoxide isomers were rapidly enzymically metabolized. No degradation of fatty acid hydroperoxides was observed with a thermally denatured enzymic extract. GC-MS identification of the volatiles formed by the reaction revealed that no volatiles were detected from the 9-hydroperoxide isomers, whereas 13-hydroperoxide of linolenic acid was cleaved into (Z)-3-hexenal, pentenols or dimers of pentene.