Molecular mapping and characterization of traits controlling fiber quality in cotton

Cotton (Gossypium spp) is the world's leading natural fiber crop. Genetic manipulation continues to play a key role in the improvement of fiber quality properties. By use of DNA-based molecular markers and a polymorphic mapping population derived from an inter specific cross between TM-1 (G. hirsutum) and 3-79 (G. barbadense), thirteen quantitative trait loci (QTLs) controlling fiber quality properties were identified in 3-79, an extra long staple (ELS) cotton. Four QTLs influenced bundle fiber strength, three influenced fiber length, and six influenced fiber fineness. These QTLs were located on different chromosomes or linkage groups and collectively explained 30% to 60%of the total phenotypic variance for each fiber quality property in the F₂ population. The effects and modes of action for the individual QTLs were characterized with 3-79 alleles in TM-1 genetic background. The results indicated more recessive than dominant, with much less additive effect in the gene mode. Transgressive segregation was observed for fiber fineness that could be beneficial to improvement of this trait. Molecular markers linked to fiber quality QTLs would be most effective in marker-assisted selection (MAS) of these recessive alleles in cotton breeding programs. This revised version was published online in August 2006 with corrections to the Cover Date.     

Inheritance of seedling and adult plant resistance to leaf rust of selected Australian spring and English winter wheat varieties

Genetic studies were conducted to gain an understanding of the inheritance of adult plant resistance (APR) to leaf rust in six common wheat varieties. The Australian varieties ‘Cranbrook’ and ‘Harrier’ each carry two genes for APR to leaf rust. These genes are genetically independent of the seedling resistance genes Lr23 and Lrl7b, carried by the respective varieties. Adult plant resistance in ‘Suneca’ was conferred by at least two genes, in addition to the seedling genes Lr1 and Lrli. It is likely that the APRs in ‘Cranbrook’, ‘Harrier’ and ‘Suneca’ are conferred by uncharacterized gene(s). Tests of allelism confirmed that seedling resistances in the varieties ‘Avocet R’, ‘Hereward’, ‘Moulin’ and ‘Pastiche’ are conferred by Lrli. Adult plant resistance in the variety ‘Hereward’ was inherited monogenically, whereas varieties ‘Moulin’ and ‘Pastiche’ each carried two dominant genes. On the basis of rust specificity and pedigree analysis, it would seem likely that the APR genes in ‘Hereward’, ‘Moulin’ and ‘Pastiche’ are also currently uncharacterized.     

Allelic relationships at the pvr1 locus in Capsicum annuum

Diseases caused by members of the Potyviridae family currently threaten pepper crops (Capsicum annuum L.) worldwide. A series of monogenic recessive resistance genes that control potyvirus resistance at the pvr1 locus in Capsicum species are widely known and used in pepper breeding programs, each allele with a differential resistance spectrum affecting a distinct range of viral strains across three viruses, Tobacco etch virus (TEV), Pepper mottle virus and Potato virus Y. In this study, we systematically analyzed the resistant spectra, and the level of the resistance each allele confers using a set of pepper genotypes homozygous or heterozygous for the following alleles; Pvr1 ⁺, pvr1, pvr1 ¹ and pvr1 ². The resistance alleles at the pvr1 locus show recessive inheritance when combined with a susceptible allele in F1 progenies. However, our results show that resistance in this system is, in fact, not always fully recessive and establish a hierarchy of allelic interactions We identified the resistance phenotype in F₁ progenies generated by combining a complete resistant allele with an incomplete resistance allele against TEV strains implying that the resistance alleles at the pvr1 shows dominant inheritance when combined with an incomplete resistance allele. Resistance alleles against TEV-HAT, pvr1 and pvr1 ², show dominance inheritance when each is combined with pvr1 ¹. The resistance allele, pvr1, shows dominance inheritance when combined with pvr1 ² against TEV-N. These results clarify the allelic relationship between resistance alleles at the pvr1 locus displaying different resistance spectra, and will assist breeders to select the preferred combinations of the resistance alleles to obtain durable resistance against multiple potyviral strains.     

Three AFLP markers tightly linked to the genic male sterility <Emphasis Type="Italic">ms</Emphasis><Subscript><Emphasis Type="Italic">3</Emphasis></Subscript> gene in chili pepper (<Emphasis Type="Italic">Capsicum annuum</Emphasis> L.) and conversion to a CAPS marker

Genic male sterility (GMS) has long been used as a tool for hybrid seed production in chili pepper (Capsicum annuum L.). We developed DNA markers linked to the GMS ms ₃ gene in a segregating population using bulked segregant analysis (BSA) and amplified fragment length polymorphism (AFLP) techniques. The segregating population was subjected to BSA-AFLP with 512 primer combinations. Three AFLP markers (Eagg/Mccc₂₇₆, Eagc/Mctt₁₇₈, and Ecag/Mtgc₂₀₄) were identified as tightly linked to the ms ₃ locus. Among them, we converted the AFLP marker Ecag/Mtgc₂₀₄ to the cleavage amplified polymorphic sequence (CAPS) marker, named GMS3-CAPS, based on sequencing analysis of internal and flanking regions for the markers between male-fertile and sterile plants. This marker will be useful for pepper breeding using the GMS system.     

Origin of the acetylated structures present in white birch (Betula pendula Roth) milled wood lignin

The occurrence and nature of acetate groups in the milled wood lignin (MWL) isolated from birch (Betula pendula Roth) has been addressed by spectroscopic (2D-NMR) and chemical degradative (derivatization followed by reductive cleavage, DFRC) methods. Considerable amounts of acetate groups were present in the MWL preparation. However, 2D-NMR analysis indicated that the lignin polymer is not extensively acetylated and that the major part of the acetate groups is attached to the xylan moieties present in the MWL preparation. Nevertheless, evidence of the presence of minor acetylation of the γ-carbon of the lignin side chain (<3% of both syringyl and guaiacyl lignin units) was provided by DFRC analysis.     

Antibacterial and antifungal activity of pinosylvin, a constituent of pine

The antibacterial and antifungal activities of pinosylvin (3,5-dihydroxy-trans-stilbene), a constituent of pine, were studied and compared with those of resveratrol (3,5,4'-trihydroxy-trans-stilbene). Pinosylvin exhibited more potent growth inhibitory activity against Candida albicans and Saccharomyces cerevisiae.     

Effect of citral,eugenol, nerolidol and α-terpineol on the ultrastructural changes of Trichophyton mentagrophytes

The antifungal effects of citral, eugenol, nerolidol and α-terpineol on Trichophyton mentagrophytes were investigated. Citral over 0.1 mg/ml strongly inhibited the hyphal growth of T. mentagrophytes, and the antifungal activity of α-terpineol was less effective. The morphological changes of the fungus exposed to the terpenes were observed by electron microscopy. The hyphae were distorted and collapsed at 0.2, 0.4 and 1 mg/ml of eugenol, nerolidol and α-terpineol respectively, and cell membrane and organelles were irreversibly damaged at 0.2 mg/ml citral.     

Solubility of kraft lignin-<Emphasis Type="Italic">g</Emphasis>-polyacrylonitrile copolymer in various ionic liquids and characterization of its solution

Lignin is a potential precursor for low-cost carbon fiber production, but it is difficult to spin and spool lignin because of its complex and interconnected molecular structure. This disadvantage can be overcome by introducing g-polyacrylonitrile (PAN) to lignin. However, the resulting copolymer is insoluble in common organic solvents. In this study, kraft lignin (KL)-g-polyacrylonitrile copolymers with different KL/PAN proportions were prepared via atom transfer radical polymerization (ATRP) method and their solubility in ionic liquids (ILs) was investigated at different temperatures. 1-Ethyl-3-methylimidazolium acetate ([EMIM]Ac), 1,3-dimethylimidazolium methyl sulfate ([MMIM]MeSO4), 1-butyl-3-methylimidazolium chloride ([BMIM]Cl), and 1-butyl-3-methylimidazolium bromide ([BMIM]Br) were used as the ILs. At all investigated temperatures, the highest solubility of KL-g-PAN was observed in [EMIM]Ac, with the order of [MMIM]MeSO4 > BMIM]Br > [BMIM]Cl. The solubility in BMIM]Br and [BMIM]Cl was remarkably low, reaching values of less than 4 g/Kg. The viscosity and surface tension of the KL-g-PAN/[EMIM]Ac solution increased and decreased, respectively, with increasing amounts of PAN and further by the addition of dimethylformamide (DMF) to the solution. FTIR spectra of KL-g-PAN copolymers before and after dissolution suggested that PAN was partially depolymerized from the copolymer during the dissolution process.