Genetic differentiation of watermelon landraces in Mozambique using microsatellite markers

Landraces of seed and dessert type watermelons from three provinces of Mozambique with distinct agro-ecological conditions, including humid and semi-dry areas from the north to the south of the country, were analysed to assess their genetic differentiation. Ninety-six accessions (269 plants) were tested with 24 microsatellite markers resulting in 110 alleles. Analysis of molecular variance showed that 63% of the total variation in the plant material could be explained among the accessions, while 37% of the variation was within accessions. Molecular variance between material used for seed extraction and dessert consumption explained 34% of the total variation whereas villages explained 27% of the molecular variation among the sampled locations. Structure analysis revealed that the material could be differentiated into three genetic groups. The seed types clustered in one genetic group, irrespective of provincial origin. Dessert type accessions from the semi-arid south and the central part were assigned to a second genetic group, while accessions from the northern more humid region of the country were assigned to a third genetic group. The observed genetic diversity may reflect farmer selection under different agro-ecological conditions or an introduction of material from different sources into the growing areas.Keywords: Citrullus lanatus, DNA fingerprinting, landraces, Mozambique, microsatellites, simple sequence repeats (SSR).African Journal of Biotechnology Vol. 12(36), pp. 5513-552

Association mapping in Scandinavian winter wheat for yield, plant height and traits important for second-generation bioethanol production

A collection of 100 wheat varieties representing more than 100 years of wheat-breeding history in Scandinavia was established in order to identify marker-trait associations for plant height, grain yield and biomass potential for bioethanol production. The field-grown material showed variations in plant height from 54 to 122 cm and in grain yield from 2 to 6.61 t ha-1. The release of monomeric sugars was determined by high-throughput enzymatic treatment of ligno-cellulosic material and varied between 0.169 and 0.312 g/g dm for glucose and 0.146 and 0.283 g/g dm for xylose. As expected, plant height and grain yield showed to be highly influenced by genetic factors with repeatability (R) equal to 0.75 and 0.53 respectively, while this was reduced for glucose and xylose (R=0.09 for both) . The study of trait correlations showed how old, low-yielding, tall varieties released higher amounts of monomeric sugars after straw enzymatic hydrolysis, showing reduced recalcitrance to bioconversion compared to modern varieties. 93 lines from the collection were genotyped with the DArTseq® genotypic platform and 5525 markers were used for genome-wide association mapping. Six QTLs for grain yield, plant height and glucose released from straw were mapped. One QTL for plant height was previously reported, while the remaining QTLs constituted new genomic regions linked to trait variation. This paper is one of the first studies in wheat to identify QTLs that are important for bioethanol production based on a genome-wide association approach