RAPD

About: RAPD is a research topic. Over the lifetime, 15960 publications have been published within this topic receiving 360391 citations.

Genetic diversity and antifungal activity of species of Pestalotiopsis isolated as endophytes from medicinal plants

Abstract: The genetic diversity of fungal endophytes in root, bark and twigs of four medicinally important plants, Azadirachta indica, Holarrhena antidysenterica, Terminalia arjuna and T. chebula were examined. Thirty isolates of Pestalotiopsis and two isolates of Bartalinia rohillardoides were genotypically compared by RAPD techniques and 241 reproducible polymorphic bands were obtained using 23 random primers. The data was subjected to unweighted pair-group (UPGMA) cluster analysis. The isolates grouped into four main clusters and subgroups, group I contained 12 isolates, group II contained 3 isolates of P. virgatula, group III contained 10 isolates including P. microspora, B. robillardoides, P. theae and Pestalotiopsis spp., group IV contained five isolates of P. microspora and finally one Pestalotiopsis spp. did not fall into any group. The ethyl acetate extracts of isolates from Terminalia arjuna showed greater antifungal activity than those from other medicinal trees against six test organisms viz., Alternaria carthami, Fusarium oxysporum, Fusarium verticilloides Macrophomina phaseolina, Phoma sorghina and Sclerotinia sclerotiorum, with the zone of inhibition ranging from 4 to 25 mm. in diameter. The results indicate that RAPD can be employed for detecting genetic diversity of Pestalotiopsis species from medicinal plants and for pre-selection of these isolates for bioactive screening programme.

Close linkage between the Cf-2/Cf-5 and Mi resistance loci in tomato

Abstract: Analysis of restriction fragment length polymorphism (RFLP) and random amplified polymorphic DNA (RAPD) markers in tomato plants segregating for resistance to the fungus Cladosporium fulvum was used to localize the resistance genes Cf-2 and Cf-5 to the same region of chromosome 6. This region, between GP79 and Aps-1, is the same as that reported for the Mi gene, which confers resistance to root-knot nematodes (meloidogyne spp.). Recombination values based on F2 populations from crosses between near-isogenic lines of L. esculentum 'Moneymaker' carrying Cf-2 or Cf-5 and Lycopersicon pennellii, indicate that this region occupies 4-5 centiMorgans (cM). However, in F2 populations from crosses between the L. esculentum stock LA1190 carrying yv and these lines, this value is 1-2 cM. The Cf-2 gene, introduced into L. esculentum from L. pimpinellifolium, is on an introgressed segment that extends from a point distal to GP79 to a point between TG232 and H2D1. The origin of Cf-5 was found to be L. esculentum var. cerasiforme rather than L. pimpinellifolium as previously reported. No RFLP markers and only one RAPD marker showed a polymorphism between Moneymaker and the near-isogenic line carrying Cf-5.

Genetic and phenetic analyses of Bradyrhizobium strains nodulating peanut (Arachis hypogaea L.) roots

Abstract: Seventeen Bradyrhizobium sp. strains and one Azorhizobium strain were compared on the basis of five genetic and phenetic features: (i) partial sequence analyses of the 16S rRNA gene (rDNA), (ii) randomly amplified DNA polymorphisms (RAPD) using three oligonucleotide primers, (iii) total cellular protein profiles, (iv) utilization of 21 aliphatic and 22 aromatic substrates, and (v) intrinsic resistances to seven antibiotics. Partial 16S rDNA analysis revealed the presence of only two rDNA homology (i.e., identity) groups among the 17 Bradyrhizobium strains. The partial 16S rDNA sequences of Bradyrhizobium sp. strains form a tight similarity (> 95%) cluster with Rhodopseudomonas palustris, Nitrobacter species, Afipia species, and Blastobacter denitrificans but were less similar to other members of the alpha-Proteobacteria, including other members of the Rhizobiaceae family. Clustering the Bradyrhizobium sp. strains for their RAPD profiles, protein profiles, and substrate utilization data revealed more diversity than rDNA analysis. Intrinsic antibiotic resistance yielded strain-specific patterns that could not be clustered. High rDNA similarity appeared to be a prerequisite, but it did not necessarily lead to high similarity values between RAPD profiles, protein profiles, and substrate utilization. The various relationship structures, coming forth from each of the studied features, had low compatibilities, casting doubt on the usefulness of a polyphasic approach in rhizobial taxonomy.

In vitro propagation of the endangered plant Centaurea ultreiae: assessment of genetic stability by cytological studies, flow cytometry and RAPD analysis

Abstract: The effect of different cytokinins on multiple shoot regeneration from shoots of Centaurea ultreiae was studied. The culture system consisted of solid basal half-strength Murashige and Skoog medium supplemented with one of four cytokinins [6-benzyladenine (BA), zeatin, kinetin, or N6-(2-isopentyl) adenine (2-iP)] at each of five different concentrations. The highest multiplication rate (5.52 shoots per explant) was obtained in the medium supplemented with 4.44 μM BA. Shoots were successfully rooted (91% success) by dipping the basal end into a solution containing 10 M 1-naphthaleneacetic acid for 30 s. Genetic stability of the regenerated plants was assessed by random amplified polymorphic DNA (RAPD) analysis and flow cytometry. In the initial randomly selected plant material (control) and 20 of its regenerants, 2,688 bands were generated by RAPD with 12 different primers, and the same banding profiles were exhibited. Molecular and cytological analyses did not reveal genomic alterations in any of the regenerated plants obtained on medium containing 4.44 μM BA. The success of acclimatization to environmental conditions—100% of plants were successfully acclimatized—suggests that the micropropagation system described is a reliable method for propagation of C. ultreiae.

Genet Dynamics of the Clonal Plant Rubus Saxatilis

Abstract: Populations of Rubus saxatilis were investigated between 1988 and 1991 in a study area (c. 2.5 km 2 ) in central Sweden. Different phases in the life cycle were studied: flowering, pollination, fruit-set, fruit-removal and seedling recruitment. Identification of genets was made by use of RAPD (random amplified polymorphic DNA). Information concerning these life-cycle phases were then used to infer processes in the population dynamics of R. saxatilis. A path analysis suggested a strong effect of fruit-set on total patch fruit production. Fruit-set varied between 6.6% and 8.3% (yearly averages) and was influenced by distance to nearest flowering conspecific patch (...)