Mapping of QTLs controlling epicotyl length in adzuki bean (Vigna angularis)

Epicotyl length (ECL) of adzuki bean (Vigna angularis) affects the efficiency of mechanized weeding and harvest. The present study investigated the genetic factors controlling ECL. An F₂ population derived from a cross between the breeding line ‘Tokei1121’ (T1121, long epicotyls) and the cultivar ‘Erimo167’ (common epicotyls) was phenotyped for ECL and genotyped using simple sequence repeats (SSRs) and single-nucleotide polymorphism (SNP) markers. A molecular linkage map was generated and fifty-two segregating markers, including 27 SSRs and 25 SNPs, were located on seven linkage groups (LGs) at a LOD threshold value of 3.0. Four quantitative trait loci (QTLs) for ECL, with LOD scores of 4.0, 3.4, 4.8 and 6.4, were identified on LGs 2, 4, 7 and 10, respectively; together, these four QTLs accounted for 49.3% of the phenotypic variance. The segregation patterns observed in F₅ residual heterozygous lines at qECL10 revealed that a single recessive gene derived from T1121 contributed to the longer ECL phenotype. Using five insertion and deletion markers, this gene was fine mapped to a ~255 kb region near the end of LG10. These findings will facilitate marker-assisted selection for breeding in the adzuki bean and contribute to an understanding of the mechanisms associated with epicotyl elongation.     

Mutation analysis of barley malt protein Z4 and protein Z7 on beer foam stability

Beer foam stability is an important characteristic. It has been suggested that isoforms of protein Z, that is, protein Z4 and protein Z7, contribute to beer foam stability. We investigated the relationship between beer foam stability and protein Z4 and protein Z7 using their deficient mutants. As a protein Z4-deficient mutant, cv. Pirkka was used. Protein Z7 deficiency was screened in 1564 barley accessions in the world collection of Okayama University, Japan. The barley samples from normal, protein Z4-deficient, protein Z7-deficient, and double-deficient were genotyped in F(2) populations and then pooled based on the DNA marker genotypes of protein Z4 and protein Z7. For a brewing trial, F(5) pooled subpopulations were used. After malting and brewing, the foam stability was determined, and the results showed that the levels of foam stability in the four samples were comparable. Two-dimensional gel electrophoresis was used to investigate the proteome in these beer samples. The results showed that low molecular weight proteins, including lipid transfer protein (LTP2), in the deficient mutants were higher than those in the normal sample. Our results suggest that the contribution of protein Z4 and protein Z7 to beer foam stability was not greater than that of other beer proteins.     

The non-recoverable phosphorus following sorption onto a Brazilian Ultisol

Phosphorus (P) immobilization in soil involves geochemical (e.g., sorption, precipitation, and diffusion) and microbiological (microbial uptake) processes. Using a Brazilian Ultisol, relative contributions of both processes to the total immobilization of applied P over 14 days were investigated. The P immobilized by microbes as interpreted by microbial suppression (achieved by mercury sterilization) was 17, 50, 54, and 56% (of the total immobilized P) on days 3, 7, 10, and 14 after fertilization, respectively. In the short-term (1 to 3 days), microbes played less of a role than did the physical effect of shaking the soil, but became the major factor by days 7 to 14. Geochemical process that might be considered short-term ageing caused only 13–16% of the total immobilization in the same time period above. Calculations supported the interpretation that measurable diffusion occurred across water films on the soil particles.     

Computer-Simulated Evaluation of the Hybrid Weakness Gene System as a Means of Preventing Genetic Contamination of Rice Cultivars

Effectivness of the hybrid-weakness caused by a complementary interaction of two dominant genes Hwc₁ and Hwc₂ to suppress the spread of the red-grain gene into ordinary white-grained rice cultivars was investigated using the Monte Carlo computer simulation method. It was shown that the weakness genes, as far as being capable of reducing the fitness of the carrier by 80 percent or more, work quite effectively to suppress the genetic contamination of white-grained cultivars due to inflow of pollen from red-grained cultivars due to inflow of pollen from red-grain gene once the gene has been incorporated in to the population in the form of red-grained progeny produced as a result of the imperfect lethality of the initial hybrid between red-and white-grained cultivars. The weakness genes have little or no effect cultivars. The weakness genes have little or no effect either, when the contamination is initiated by an inflow of seeds or seedlings from ed-grained cultivars in these situations, removal (selection)of red grained plants Is the only countermeasure to exterminate the red-grain gene. The removal of red grained plants need not be intensive if carried out continuously. The spread of the red-grain gene after initial contamination is suppressed if the red-grain gene and weakness genes are linked. The suppressing effect of the linkage, however, is not substantial when the outcrossing rate is around or smaller than 0.01 as can be assumed in most rice cultivars.     

Herbivore-induced volatiles from tea (Camellia sinensis) plants and their involvement in intraplant communication and changes in endogenous nonvolatile metabolites

As a defense response to attacks by herbivores such as the smaller tea tortrix ( Adoxophyes honmai Yasuda), tea ( Camellia sinensis ) leaves emit numerous volatiles such as (Z)-3-hexen-1-ol, linalool, α-farnesene, benzyl nitrile, indole, nerolidol, and ocimenes in higher concentration. Attack of Kanzawa spider mites ( Tetranychus kanzawai Kishida), another major pest insect of tea crops, induced the emission of α-farnesene and ocimenes from tea leaves. The exogenous application of jasmonic acid to tea leaves induced a volatile blend that was similar, although not identical, to that induced by the smaller tea tortrix. Most of these herbivore-induced plant volatiles (HIPV) were not stored in the tea leaves but emitted after the herbivore attack. Both the adaxial and abaxial epidermal layers of tea leaves emitted blends of similar composition. Furthermore, HIPV such as α-farnesene were emitted mostly from damaged but not from undamaged leaf regions. A principal component analysis of metabolites (m/z 70-1000) in undamaged tea leaves exposed or not to HIPV suggests that external signaling via HIPV may lead to more drastic changes in the metabolite spectrum of tea leaves than internal signaling via vascular connections, although total catechin contents were slightly but not significantly increased in the external signaling via HIPV.     

Genotypic variation in Fe concentration of barley grain

Abstract

Iron deficiency in humans is the most prevalent micronutrient deficiency worldwide. To screen for high Fe cultivar, genotypic variation in Fe concentration of barley grain was investigated in two collections of barley: 274 standard varieties selected at the Barley Germplasm Center of the Research Institute for Bioresources, Okayama University (SV) and 135 varieties from the Barley Core Collection of Americas (BCCAM). The Fe concentration of barley grain showed large variation, ranging from 24.6 to 63.3 mg kg^?1 in SV, from 21.0 to 83.0 mg kg^?1 in BCCAM barleys. The Fe concentration was not affected by the key characters of barley varieties, kernel row types, and hulled or hull-less. The Fe concentration was also not related to the place of origin of the barley variety. About 90% of total Fe was localized in the grain without hull. These results provide fundamental data for breeding Fe-rich cultivars and for studying the mechanisms involved in genotypic variation in Fe concentration.     

Indica-japonica differentiation in Chinese rice landraces

Summary Ninety Chinese rice landraces were examined with special reference to the indica-japonica differentiation in terms of traditional criteria, isozyme analysis and PCR analysis of the chloroplast DNA (cpDNA). Cultivars were separated into indica and japonica defined by a discriminant function (Z) based on key characters, as well as by isozyme genotypes. Most indica landraces had chloroplast DNAs with a deletion at the Pst-12 fragment, while most japonica landraces had cpDNAs without the deletion. Two traditionally recognized varietal groups in China, keng and hsien, corresponded largely to the respective japonica and indica revealed in our study. The results obtained in this study showed good agreement for classification of indica and japonica types by the three methods: discriminant analysis by Z value, isozyme analysis, and PCR analysis for cpDNA.     

Mapping genes for deep-seeding tolerance in barley

Deep-seeding tolerance, the emergence of seedlings from deep seeded conditions, is involved in stand establishment in semi-arid regions, where the soil surface is too dry for seed germination. Genes determining deep-seeding tolerance in barley were mapped using two doubled haploid populations derived from the following crosses: Harrington × TR306 (H/T)and Step toe × Morex (S/M). Significant quantitative trait loci (QTLs) for deep-seeding tolerance were found in each population. Two QTL sex plained 40% of the phenotypic variation in the H/T population and one QTL (S/M) 8% of the total phenotypic variance. Multiple QTLs accounting for coleoptile length and first internode length were detected in both populations. In the H/T population, there were coincident QTLs for deep-seeding tolerance, coleoptile length and first internode length on the long arm of chromosome 5H. These QTLs correspond with previously reported QTLs for abscisic acid and gibberellic acid response. QTL coincidence may be due to the pleiotropic effects of alleles at a single locus. This information may be useful for breeding programs manipulating morphological and physiological traits in order to develop varieties for semi-arid regions. This revised version was published online in August 2006 with corrections to the Cover Date.