Progeny test of tetraploid Betula platyphylla and preliminary selection of hybrid parents
Estimating genetic parameters of parental lines through progeny testing and choosing good hybrid parents are important for genetically improving seed orchard trees. In this study, 24 tetraploid progeny seedlings were used as experimental materials, which came from test cross design: six tetraploid Betula platyphylla lines (Q33, Q13, Q103, Q19, Q83 and Q14) as female parents and four individual B. platyphylla diploid lines (F3, F4, F9 and F11) as male parents were crossed. Variance analysis of height, diameter, height-to-diameter ratio, and internodal distance showed that the differences between hybrid combinations reached highly significant levels. Using multi-objective decisionmaking, we performed a comprehensive assessment of the various hybrid combinations. Using a selection rate of 20 % of the standard, five hybrids were selected; their genetic gains in average height, diameter, height-to-diameter ratio, and internodal distance were 20.95, 6.07, 13.07 and 8.96 %, respectively. We also analyzed the combining ability and genetic parameter effect values of parents and hybrid combinations. The combined analysis revealed that Q13, Q103, Q33 and Q83 were superior females; F3, F4, and F9 were superior males; and F3 × Q13, F4 × Q83 and F9 × Q33 were superior hybrid combinations. The heights and diameters of these progenies were 22.49 and 11.48 % greater than average, respectively.
Variation and growth adaptability analysis of transgenic Populus simonii×P. nigra lines carrying TaLEA gene
A totlal of 12 Populus simonii×P. nigra lines (11 transgenic Populus lines and one control line) in 2 years old were used to study the phenotypic variation of tree height(H) and basic diameter(BD) in 6 different sites. The analysis of variance showed that there was a remarkable difference in H and BD among sites (P0.01), lines (P0.01), and sites×lines (P0.05). The average H and BD of transgenic poplar lines ranged in 128- - 235 cm and 13- - 24 mm in different sites respectively. The coefficients of H and BD of transgenic poplar lines changed in 19.84%- - 33.38% and 24.21%- - 49.16% and repeatabilities ranged in 0.497- - 0.952,indicating that the variation of poplar transgenic lines was strongly controlled by genetic factors,which were in favor of line selection. Tai model was introduced to analyse the genetic adaptability of poplar lines in different sites. The results showed that except line XL11, other lines grew steady in different sites. Based on the genetic adaptability parameter and the domino effect values of interaction between H and environment, the most adapted site of each line was predicted. Lines XL9, XL1 and XL14 are high biomass and strong stability, which are suitable generalized in 6 different sites.
Optimal Combination and Concentration of Antibiotics in Media for Isolation of Pathogenic Fungi and Nocardia asteroides
Strains of Blastomyces dermatitidis, Sporothrix schenckii, Histoplasma capsulatum, Cryptococcus neoformans, Nocardia asteroides, and Coccidioides immitis were tested for in vitro susceptibility to polymyxin, gentamicin, kanamycin, chloramphenicol, and neomycin at concentrations of 1, 2, 4, 8, and 16 μg/ml. Polymyxin was the most inhibitory and gentamicin was the least inhibitory of the five antibiotics. Two Histoplasma mycelial strains were partially inhibited by 2 and 8 μg of gentamicin per ml and showed at least a 2+ growth at the higher antibiotic concentration. Kanamycin and neomycin produced significant inhibition of N. asteroides but otherwise were noninhibitory. A combination of chloramphenicol and kanamycin, each at 16 μg/ml, and gentamicin, at 4 μg/ml, was noninhibitory to the strains tested except for N. asteroides. Chloramphenicol at 16 μg/ml was not inhibitory for N. asteroides. The results suggest that the optimal antibiotic combination to use in the isolation of fungi and higher bacteria is chloramphenicol, 16 μg/ml, and gentamicin, 4 μg/ml. Addition of sheep blood (5%) had no effect on antibiotic susceptibility of the organisms studied.