Jung-Gon Kim

Inheritance of (1–3)(1–4)-beta-D-glucan content in barley ( Hordeum vulgare L.)

Abstractβ-glucan is the soluble dietary fiber component and occurs at its highest in barley. This study aims to evaluate the inheritance of β-glucan content in barley grains and to map quantitative trait loci (QTL) associated with this trait. F5-derived 107 lines from the cross of the six-rowed waxy hulless barley, ‘Yonezawa Mochi’ and the six rowed non-waxy hulless barley,’ Neulssalbori’ were measured for their agronomic traits and β-glucan level at four different environments. These recombinant lines showed significant genotypic variation (P < 0.01) and normal distribution for β-glucan content with a range of 43.6–62.1 g kg−1 across environments. A significant genotype-by-environment interaction was also found. The broad-sense heritability estimates for β-glucan content ranged from 0.42 to 0.82 across environments. Using one-factor analysis and composite interval mapping, a main effect of QTL associated with β-glucan content was identified in the genomic region near waxy gene (wx) and HVM4 on chromosome 7H. The major QTL at this region explained on average 44.4% of the variation for the mean of β-glucan content across environments with LOD values that ranged from 5.7 in Suwon in 2001 to 13.9 in Suwon in 2003. Two minor QTLs were identified but their significance of association with β-glucan content was inconsistent across environments.

Estimation of genetic distance and its predictability of F1 hybrid performance in barley

Heterotic performance of hybrids is dependent upon the amount of genetic variability among parents and combining ability of alleles at the loci associated with target traits. This study was carried out to determine if (1) pedigree-based genetic distance could explain molecular levels of genetic diversity, and (2) molecular marker-based genetic distance could predict the degree of hybrid performance in barley. The average value of Random Amplified Polymorphic DNA (RAPD)-based genetic similarity for all 58 genotypes was 0.641. Twenty-two hulless barley and eight malt barley varieties showed low levels of genetic diversity with higher similarity values than the average of all or of the hulled barley variety pool. Coefficients of parentage (COPs) computed for 1,653 pairs of 58 Korean barley varieties ranged from 0 to 0.984 with a mean of 0.048. Correlation between the genealogical and RAPD-based genetic similarity matrices was 0.256 (P < 0.01). Correlation values for the related and for all (related + unrelated) genotype pairs were almost similar to each other, indicating that the unrelated genotypes share a large portion of genomes alike in state, not identical by descent. RAPD-based genetic similarity estimates among parents were poorly correlated with their hybrid performance such as 1,000-grain weight (r = 0.34), biomass yield (r = −0.12), and grain yield (r = −0.04) for 11 genotype pairs of hulled barley. However, correlations between heterozygosity at marker loci and hybrid performance for biomass and grain yield slightly increased when two F1 hybrids were excluded in the analysis due to their low yield.

Isolation and Biological Characterization of Barley mild mosaic virus(BaMMV) Mild and Severe Strains in Korea

Two distinct and stable isolates of Barley mild mosaic virus(BaMMV) designated as Naju82-S(severe) and Naju82-M(mild) were obtained. These two isolates differed in their symptomatology, virus transmission characteristics and cultivar specificity at various temperature. Thus, these isolates were referred to as strains in this study. BaMMV Naju-S strain showed severe mosaic symptoms accompanied by necrosis on the infected leaves. Naju82-S strain is more virulent demonstrated by shorter incubation period and relatively high virus concentration than Naju82-M strain. Five Korean cultivars were tested for their pathogenicity to different strains based on the rate of infection. Results showed that infection rate of cultivars to both strains did not significantly differed from each other. However, under different temperatures, the pathogenicity on the two cultivars such as cultivars Hopumbori and Sessalbori were significantly affected. Hopumbori was moderately resistant to both strains at and susceptible at . Similarly, Sessalbori was moderately resistant at to both strains but distinctly differentiated at wherein it was resistant to mild strain and highly susceptible to severe strain. Other cultivars including Baegdong, Jinyangbori and Neahanssalbori consistently showed susceptible reaction to both strains at varying temperatures tested in this study.