Genetic characterization and QTL mapping for grain fructan in wheat (Triticum aestivum L.).

Fructans are polysaccharides that are made up mainly of fructose. They are non-digestible carbohydrates and act as prebiotics to selectively promote the growth of colonic bifidobacteria, thereby improving human gut health. Fructans are present in the grain of wheat (Triticum aestivum L.), a staple food crop. Until now, there has been no research on genetic improvement of the concentration of fructans in wheat grain, partly because it has been difficult to accurately measure. One aim of this research project was to develop a simple and effective method to measure the fructan concentration in wheat grain. This was achieved by modifying a method that involves extraction of fructans from wheat grain followed by enzymatic hydrolysis to break down fructans into monosaccharides and quantification by anion-exchange liquid chromatography coupled with pulsed amperometric detection. The modified procedure is reliable and allows the handling of large numbers of flour samples at a relatively low cost, and can therefore be useful for assessing large numbers of wheat breeding lines. Using this method, grain samples taken from a diverse set of 117 wheat cultivars and breeding lines, including parents of mapping populations, were analysed for grain fructan concentration. There was significant genotypic variation among these materials, with grain fructan concentration ranging from 0.3 to 2.3% of grain dry weight. There was no evidence of strong genotype-byenvironment interaction; the fructan concentrations of the same genotypes were positively correlated over different environments in Australia. Genetic mapping was carried out to detect and map loci affecting grain fructan concentration in wheat using a doubled haploid population derived from a cross between Berkut (high fructan) and Krichauff (low fructan). Grain samples were obtained from two field sites in South Australia and one in Kazakhstan. Fructan concentration varied widely within the population (0.6-2.6% of grain dry weight), with heritability estimated as h² = 0.71. A linkage map of 528 molecular markers covering 21 wheat chromosomes was used for locating quantitative trait loci (QTL). Genetic mapping identified two major QTLs on chromosomes 6D and 7A, with the (high fructan concentration) alleles contributed from Berkut, contributing to a 30-40% increase in wheat grain fructan compared to the Krichauff alleles. Effects of these chromosome regions were validated in additional environments and in another mapping population, Sokoll/Krichauff, with the favourable alleles contributed from Sokoll. The major QTL on chromosome 7A was in the same region with a reported fructosyltransferase orthologue (AB029888), while the major QTL on chromosome 6D seemed to be co-located with a reported gene encoding for a fructan-degrading enzyme 1-exohydrolase (1-FEHw2). It is concluded that grain fructan concentration of wheat can be improved by breeding and that molecular markers could be used to select effectively for favourable alleles in two regions of the wheat genome.Thesis (Ph.D.) - University of Adelaide, School of Agriculture, Food and Wine, 200

Genetic mapping and legume synteny of aphid resistance in African cowpea (Vigna unguiculata L. Walp.) grown in California.

The cowpea aphid Aphis craccivora Koch (CPA) is a destructive insect pest of cowpea, a staple legume crop in Sub-Saharan Africa and other semiarid warm tropics and subtropics. In California, CPA causes damage on all local cultivars from early vegetative to pod development growth stages. Sources of CPA resistance are available in African cowpea germplasm. However, their utilization in breeding is limited by the lack of information on inheritance, genomic location and marker linkage associations of the resistance determinants. In the research reported here, a recombinant inbred line (RIL) population derived from a cross between a susceptible California blackeye cultivar (CB27) and a resistant African breeding line (IT97K-556-6) was genotyped with 1,536 SNP markers. The RILs and parents were phenotyped for CPA resistance using field-based screenings during two main crop seasons in a 'hotspot' location for this pest within the primary growing region of the Central Valley of California. One minor and one major quantitative trait locus (QTL) were consistently mapped on linkage groups 1 and 7, respectively, both with favorable alleles contributed from IT97K-556-6. The major QTL appeared dominant based on a validation test in a related F2 population. SNP markers flanking each QTL were positioned in physical contigs carrying genes involved in plant defense based on synteny with related legumes. These markers could be used to introgress resistance alleles from IT97K-556-6 into susceptible local blackeye varieties by backcrossing

A major QTL corresponding to the Rk locus for resistance to root-knot nematodes in cowpea (Vigna unguiculata L. Walp.).

Key messageGenome resolution of a major QTL associated with the Rk locus in cowpea for resistance to root-knot nematodes has significance for plant breeding programs and R gene characterization. Cowpea (Vigna unguiculata L. Walp.) is a susceptible host of root-knot nematodes (Meloidogyne spp.) (RKN), major plant-parasitic pests in global agriculture. To date, breeding for host resistance in cowpea has relied on phenotypic selection which requires time-consuming and expensive controlled infection assays. To facilitate marker-based selection, we aimed to identify and map quantitative trait loci (QTL) conferring the resistance trait. One recombinant inbred line (RIL) and two F2:3 populations, each derived from a cross between a susceptible and a resistant parent, were genotyped with genome-wide single nucleotide polymorphism (SNP) markers. The populations were screened in the field for root-galling symptoms and/or under growth-chamber conditions for nematode reproduction levels using M. incognita and M. javanica biotypes. One major QTL was mapped consistently on linkage group VuLG11 of each population. By genotyping additional cowpea lines and near-isogenic lines derived from conventional backcrossing, we confirmed that the detected QTL co-localized with the genome region associated with the Rk locus for RKN resistance that has been used in conventional breeding for many decades. This chromosomal location defined with flanking markers will be a valuable target in marker-assisted breeding and for positional cloning of genes controlling RKN resistance

Association Studies and Legume Synteny Reveal Haplotypes Determining Seed Size in Vigna unguiculata.

Highly specific seed market classes for cowpea and other grain legumes exist because grain is most commonly cooked and consumed whole. Size, shape, color, and texture are critical features of these market classes and breeders target development of cultivars for market acceptance. Resistance to biotic and abiotic stresses that are absent from elite breeding material are often introgressed through crosses to landraces or wild relatives. When crosses are made between parents with different grain quality characteristics, recovery of progeny with acceptable or enhanced grain quality is problematic. Thus genetic markers for grain quality traits can help in pyramiding genes needed for specific market classes. Allelic variation dictating the inheritance of seed size can be tagged and used to assist the selection of large seeded lines. In this work we applied 1,536-plex SNP genotyping and knowledge of legume synteny to characterize regions of the cowpea genome associated with seed size. These marker-trait associations will enable breeders to use marker-based selection approaches to increase the frequency of progeny with large seed. For 804 individuals derived from eight bi-parental populations, QTL analysis was used to identify markers linked to 10 trait determinants. In addition, the population structure of 171 samples from the USDA core collection was identified and incorporated into a genome-wide association study which supported more than half of the trait-associated regions important in the bi-parental populations. Seven of the total 10 QTLs were supported based on synteny to seed size associated regions identified in the related legume soybean. In addition to delivering markers linked to major trait determinants in the context of modern breeding, we provide an analysis of the diversity of the USDA core collection of cowpea to identify genepools, migrants, admixture, and duplicates

Two-Phase Defect Detection Using Clustering and Classification Methods

Autonomous fault management of network and distributed systems is a challenging research problem and attracts many research activities. Solving this problem heavily depends on expertise knowledge and supporting tools for monitoring and detecting defects automatically. Recent research activities have focused on machine learning techniques that scrutinize system output data for mining abnormal events and detecting defects. This paper proposes a two-phase defect detection for network and distributed systems using log messages clustering and classification. The approach takes advantage of K-means clustering method to obtain abnormal messages and random forest method to detect the relationship of the abnormal messages and the existing defects. Several experiments have evaluated the performance of this approach using the log message data of Hadoop Distributed File System (HDFS) and the bug report data of Bug Tracking System (BTS). Evaluation results have disclosed some remarks with lessons learned

Genomic regions, cellular components and gene regulatory basis underlying pod length variations in cowpea (V. unguiculata L. Walp).

Cowpea (V. unguiculata L. Walp) is a climate resilient legume crop important for food security. Cultivated cowpea (V. unguiculata L) generally comprises the bushy, short-podded grain cowpea dominant in Africa and the climbing, long-podded vegetable cowpea popular in Asia. How selection has contributed to the diversification of the two types of cowpea remains largely unknown. In the current study, a novel genotyping assay for over 50 000 SNPs was employed to delineate genomic regions governing pod length. Major, minor and epistatic QTLs were identified through QTL mapping. Seventy-two SNPs associated with pod length were detected by genome-wide association studies (GWAS). Population stratification analysis revealed subdivision among a cowpea germplasm collection consisting of 299 accessions, which is consistent with pod length groups. Genomic scan for selective signals suggested that domestication of vegetable cowpea was accompanied by selection of multiple traits including pod length, while the further improvement process was featured by selection of pod length primarily. Pod growth kinetics assay demonstrated that more durable cell proliferation rather than cell elongation or enlargement was the main reason for longer pods. Transcriptomic analysis suggested the involvement of sugar, gibberellin and nutritional signalling in regulation of pod length. This study establishes the basis for map-based cloning of pod length genes in cowpea and for marker-assisted selection of this trait in breeding programmes

SURVEY ON VOCABULARY LEARNING STRATEGIES OF HIGH–QUALITY ENGLISH STUDIES PROGRAM STUDENTS, SCHOOL OF FOREIGN LANGUAGES, CAN THO UNIVERSITY, VIETNAM

This research study aimed to investigate the usage of vocabulary learning strategies among English Studies students at Can Tho University (CTU), specifically those under the high-quality program at the School of Foreign Languages (SFL). The primary objective of the study was to identify the most commonly used strategies for learning English vocabulary and to compare the similarities and differences in how these strategies were applied among students by academic year. A total of 200 survey responses from SFL, CTU got involved in the study, and 12 of whom joined a semi-structured interview. The data gathered were analyzed using both descriptive and inferential statistical techniques. The results of this study provided insights into effective vocabulary learning strategies and would facilitate the improvement of English language teaching and learning practices at the university level.  Article visualizations