Molecular breeding (Plant Biology)

Aim: This study aimed to uncover the diversity and population structure of 128 sesame genotypes using ISSR markers and identify highly diverse genotypes for the purposes of broadening the genetic base of sesame landraces grown in Ethiopia. Place and Duration of Study: The study was conducted in Botany research laboratory of Kasetsart University, Thailand, from April to July, 2013. Methodology: Genomic DNA of 128 sesame genotypes were subjected to PCR amplification and electrophoresis using seven ISSR markers and a binary data matrix prepared for each primer by scoring clear bands. The data generated were used to calculate the number of total bands (TB), Original Research Article Abate et al.; BBJ, 8(4): 1-13, 2015; Article no.BBJ.18481 2 polymorphic bands (PB), polymorphism percentage (P %) and polymorphic information content (PIC) for each locus. The number of different (Na) and effective (Ne) alleles, polymorphic loci (%), Shannon's information index (I) and Nei's gene diversity (He) for each population were calculated using GenAlEx 6.5 software. The data were also subjected to analysis of molecular variance (AMOVA) and principal coordinate analysis (PCoA) via distance matrix. Fixation index (Fst) was computed to measure genetic differentiation among populations. Genetic associations among individual genotypes were determined based on dissimilarity matrix using Darwin version 5.0 and a Neighbour-Joining hierarchal tree was constructed based on UPGMA. Results: The 7 ISSR primers in 128 sesame genotypes yielded 96 reproducible amplified bands. The number of amplified bands varied from 7 to 19. Out of 96 bands, 89 (92.2%) were polymorphic. Average number of bands and polymorphic bands per primer were 14 and 12.6 respectively. The polymorphic information content (PIC) value ranged between 0.26 and 0.76, showing the high informativeness of the selected primers. The overall gene diversity and Shannon's information index were 0.37 and 0.54 respectively. Average dissimilarity value among the genotypes was 0.39. Maximum dissimilarity (0.88) was observed between genotypes Amr-NW6 and Amr-NG9 and less dissimilarity (0.014) was recorded between Amr-NW1 and Amr-NG1. SNNP-7 was the most diverse of all genotypes with highest average dissimilarity value of 0.77. AMOVA showed lower genetic divergence between populations (6%) than within population (94%) with average Fst of 0.061 across populations. The high intra-population variation could be because of large number of genotypes included and due to high out-crossing nature of sesame. Clustering and PCoA analyses clustered the genotypes into individual groups where most of the landraces were grouped in separate clusters irrespective of their geographic origins, while the cultivars were grouped in one cluster, suggesting less variability within the released varieties than the landraces. Accessions no. 56, 73, and 105 were out grouped from the rest. Conclusion: There exist considerable variations among sesame genotypes collected from different geographical regions of Ethiopia. Genotypes Amr-NSh-6, Benishangul-6 and SNNP-7 exhibited a good amount of genetic divergence and hence can be used in crossing program for genetic improvement of sesame in Ethiopia.

Smallholder sugarcane production sector is under researched and underdeveloped with limited industrial link and support. The objectives of this study were to assess the current state of sugarcane production, farmers' perceived production constraints and preferred traits, and to collect germplasm grown by smallholder farmers in southern Ethiopia for strategic breeding and conservation. The study was conducted across 16 administrative zones, 28 districts and 56 peasant associations involving 560 smallholder sugarcane growers in southern Ethiopia using a participatory rural appraisal approach. Sugarcane genetic resources were collected through structured sampling. Findings from this study indicated that monocropping was identified as the predominant sugarcane farming system. Respondent farmers prioritized drought tolerance (21%), increased cane yield (20%), early maturity (18%), marketability (17%), and high biomass (14%) as the top preferred traits of sugarcane. Ninety diverse sugarcane landraces were collected from homesteads of smallholder farmers. Findings from this study would serve as baseline information towards sugarcane research and development emphasizing the constraints and preferences of smallholder sugarcane growers in Ethiopia or similar agro-ecologies.

The linkage map for the recombinant inbred line (RIL) mapping population derived from late leaf spot (LLS) and rust disease susceptible (TAG 24) and resistant (GPBD 4) varieties of peanut was improved by adding 139 new SSR and transposable element (TE) markers. The improved map now has 289 mapped loci with a total map distance of 1730.8 cM and average inter-marker distance of 6.0 cM across 20 linkage groups. Quantitative trait loci (QTL) analysis using improved genetic map with 289 markers and comprehensive phenotypic data for LLS and rust from 11 seasons could identify a region on linkage group AhXV (B03 linkage group of B genome) which contributed significantly towards LLS and rust resistance. Of the five QTL mapped in this region, three showed high phenotypic variance explained (PVE) for both LLS and rust, and two QTL showed high PVE for only rust. The QTL flanked by GM2009-IPAHM103 had very high PVE of 44.5 % and 53.7 %, respectively for LLS and rust response. Another genomic region on AhXII (B10 linkage group of B genome) contained a

Traditional basmati rice varieties are very low yielding due to their poor harvest index, tendency to lodging and increasing susceptibility to foliar diseases; hence there is a need to develop new varieties combining the grain quality attributes of basmati with high yield potential to fill the demand gap. Genetic control of basmati grain and cooking quality traits is quite complex, but breeding work can be greatly facilitated by use of molecular markers tightly linked to these traits. A set of 209 recombinant inbred lines (RILs) developed from a cross between basmati quality variety Pusa 1121 and a contrasting quality breeding line Pusa 1342, were used to map the quantitative trait loci (QTLs) for seven important quality traits namely grain length (GL), grain breadth (GB), grain length to breadth ratio (LBR), cooked kernel elongation ratio (ELR), amylose content (AC), alkali spreading value (ASV) and aroma. A framework molecular linkage map was constructed using 110 polymorphic simple sequence repeat (SSR) markers distributed over the 12 rice chromosomes. A number of QTLs, including three for GL, two for GB, two for LBR, three for aroma and one each for ELR, AC and ASV were mapped on seven different chromosomes. While location of majority of these QTLs was consistent with the previous reports, one QTL for GL on chromosomes 1, and one QTL each for ELR and aroma on chromosomes 11 and 3, respectively, are being reported here for the first time. Contrary to the earlier reports of monogenic recessive inheritance, the aroma in Pusa 1121 is controlled by at least three genes located on chromosomes 3, 4 and 8, and similar to the reported association of badh2 gene with aroma QTL on chromosome 8, we identified location of badh1 gene in the aroma QTL interval on chromosome 4. A discontinuous 5 + 3 bp deletion in the seventh exon of badh2 gene, though present in all the RILs with high aroma, was not sufficient to impart this trait to the rice grains as many of the RILs possessing this deletion showed only mild or no aroma expression.

Seeds of Capsicum annuum L. var. G4 were subjected to different concentrations of
methyl methane sulphonate (MMS) and diethyl sulphate (DES). The effects of different mutagenic
treatments on meiosis, chiasma frequency, and pollen fertility have been studied in M1 generation.
Various types of meiotic aberrations such as univalent, multivalent, stickiness, bridge, laggards,
cytomixis etc. were observed in all the treatments. However, the MMS treatments proved to be
more effective in inducing meiotic aberrations as compared to DES. Moreover, the frequency of
meiotic aberrations was at its maximum at metaphase followed by anaphase and telophase stages.
As the concentrations increase, reduction in chiasma frequency and pollen fertility was observed in
all the treatments and, MMS again was found to be more effective than DES treatments.
ª 2012 King Saud University. Production and hosting by Elsevier B.V. All rights reserved