University of Greenwich

About: University of Greenwich is a education organization based out in London, United Kingdom. It is known for research contribution in the topics: Population & Context (language use). The organization has 3749 authors who have published 9958 publications receiving 234340 citations.

Identification and mapping of AFLP markers linked to peanut (Arachis hypogaea L.) resistance to the aphid vector of groundnut rosette disease

Abstract: Groundnut rosette disease is the most destructive viral disease of peanut in Africa and can cause serious yield losses under favourable conditions. The development of disease-resistant cultivars is the most effective control strategy. Resistance to the aphid vector, Aphis craccivora, was identified in the breeding line ICG 12991 and is controlled by a single recessive gene. Bulked segregant analysis (BSA) and amplified fragment length polymorphism (AFLP) analysis were employed to identify DNA markers linked to aphid resistance and for the development of a partial genetic linkage map. A F2:3 population was developed from a cross using the aphid-resistant parent ICG 12991. Genotyping was carried out in the F2 generation and phenotyping in the F3 generation. Results were used to assign individual F2 lines as homozygous-resistant, homozygous-susceptible or segregating. A total of 308 AFLP (20 EcoRI+3/MseI+3, 144 MluI+3/MseI+3 and 144 PstI+3/MseI+3) primer combinations were used to identify markers associated with aphid resistance in the F2:3 population. Twenty putative markers were identified, of which 12 mapped to five linkage groups covering a map distance of 139.4 cM. A single recessive gene was mapped on linkage group 1, 3.9 cM from a marker originating from the susceptible parent, that explained 76.1% of the phenotypic variation for aphid resistance. This study represents the first report on the identification of molecular markers closely linked to aphid resistance to groundnut rosette disease and the construction of the first partial genetic linkage map for cultivated peanut.

Oblique to Orthogonal Convergence Across the Turan Block in the Post-Miocene

Abstract: The 2-17-km-thick, post-Triassic sediments of the Turan continental block accumulated in a south-dipping basin characterized by fault-controlled facies and thickness variations. Since the late Miocene, the thickest part of the basin fill, on the southern margin of the Turan block, has been folded and uplifted as the Kopet Dag range, in response to the Iran-Turan convergence. The Apsheron sill, which separates the northern continental from the southern oceanic Caspian Sea basins, links the Kopet Dag-Greater Balkan ranges (Turkmenistan) to the Caucasus (Azerbaijan). The large-scale east-west- to west-northwest-east-southeast-oriented arrays of periclinal folds of the Kopet Dag range, which indicate a north-south oriented compression, were generated by a fault propagation mechanism. The migration and accumulation of hydrocarbons has been controlled by the deformation pattern. The 75 km of north-south shortening in the western Kopet Dag-Greater Balkan area can be resolved into 70 km of pure compression, orthogonal to the N120°-oriented Ashgabat fault, and 35 km of dextral slip along this fault. The north-south Iran-Asia relative motion has produced the oblique convergent northwest-southeast structures along the dextral Ashgabat fault and the pure convergent east-west structures in the western Kopet Dag-Greater Balkan region. The orientation of the structures has been controlled by the angular relationship between the relative motion of two blocks and the orientation of their boundaries. The Ashgabat fault as a major crustal anisotropy has concentrated the deformation into a narrow fold and thrust belt, whereas in the west the deformation is distributed over a wider area. The pattern of deformation has been controlled by the Iran-Turan boundary conditions.