1. To enhance genetic variability in eggplant, the eggplant was treated by EMS previous. In this study, the M2 generation of the mutants was investigated. A total 325 independent M2 families comprising 1142 M2 plants were investigated for phenotypic variation (Fig 1), and all visible phenotypes were divided into 15 major categories and 38 second categories and 437 phenotypic categories were investigated. 280 mutants were identified from the 1142 M2 plants according to the visible phenotype variation. Among 280 mutants, 189 mutants showed only one phenotypic category and 91 mutants showed more than one phenotypic category. Besides the visible phenotypes variation, the content of chlorogenic acid also was analyzed in the 26 mutants’ fruits by HLPC. 17 of 26 M2 plant chlorogenic acids were significantly higher than that in wild type eggplant fruit. Additionally, compared with the wt eggplant, the content of anthocyanin of purple black mutant increased while the content of anthocyanin of green and white mutant decreased. The RT-PCR result showed that except SmPAL, other anthocyanin biosynthetic gene and the regulator SmMYB1 expression level increased in the purple black mutant and decreased in the green and white mutant. Above all, the M2 generation presented abundant phenotypic variation and was potential for eggplant breeding and molecular research.
Fig 1
2. Screening, identification and optimization of fermentation conditions of an antagonistic actinomycete strain XL-6 to Ralstoniasolanacearum
To isolate and screen antagonistic actinomycetes strains with inhibitory activity on Ralstoniasolanacearum from the rhizosphere soil of healthy eggplants, Actinomycete was isolated by Pour Plate method. Antagonistic actinomycete was screened by double agar layer plaque technique, agar diffusion assay and confrontation culture in vitro. Strain XL-6 was identified by morphological, culture, physiological and biochemical characteristics and 16S rRNA sequence analysis. The fermentation condition was optimized by single factor and orthogonal experiment. Strain XL-6 showed antagonistic to Ralstoniasolanacearum and three other pathogens. StrainXL-6 belonged to Streptomyces rochei. The optimum culture conditions of strain XL-6 was with a medium of 3% cornmeal, 0.5% Yeast powder, 0.2% K2HPO4, 0.2% MgCl2, 0.1% NaCl at initial pH of 7.0, liquid volume 70 ml in 250 ml flask, 180 rpm at 28 ℃, inoculation size of 6% for 6 d. Strain XL-6 was identified as Streptomyces.
3.The research on stability of antibiotic activity of fermented broth of strain XL-6 and on bacterial wilt control in eggplant seedlings and plant growth
In order to develop nontoxic and efficient biological pesticides, a pot experiment was carried out to study the stability of antibiotic activity of fermented broth of a self-isolated strain XL-6 belonged to Streptomyces rochei and on bacterial wilt control in eggplant seedlings and plant growth. The result showed that the active substances inhibiting R. solanacearumin the fermentation broth had certain tolerance to UV，temperature and pH Proteinase K and trypin had little impact on antimicrobial substances; Meanwhile, the antibiotic activity of fermented broth stored at 4℃had a better stability. The 40-times dilution fermentation significant promoted the growth and significant increased the seed germination rates, plant height, number of roots more than the other fermentation with different dilution; meanwhile ,significant increased chlorophyll content and activity of root. The 40-times dilution stimulated the activities of enzymes related to disease resistance, such as PAL and PPO, and raised the ability of disease resistance, Furthermore, the incidence and disease index significant reduced by 45.6% and 32.8, respectively, which led to a relative control efficacy of 64.78%, and better effect were obtained than spore germination of XL-6. The results indicated that the suitable dilution fermentation of XL-6 could control bacterial wilt occurrence in eggplant and promote plant growth.
4. The Effect of Silicon and Ralstoniasolanacearum Interaction to the activity of antioxidant enzymes of Eggplant Seeding
The objective of this study was to investigate the activity of antioxidant enzymes of silicon induced resistance of eggplant seeding to bacterial wilt, two different resistance eggplant materials were used throughout the hydroponic cultivation. The results showed that exogenous silicon significantly reduced the disease index of bacterial wilt, meanwhile, significantly increased root activity; For the susceptible to R. solanacearum of eggplant , Before R. solanacearum inoculation, Si amendments had no effect on activity of PAL and PPO as well as non-Si-treatment, After R. solanacearum inoculation, compared with the non-Si-treatment, Si supply significantly increased the activity of PAL and PPO; But for the resistance to R. solanacearum of eggplant, the activity of PAL and PPO treated with Si amendment were significantly higher than non-Si-treatment respectively. The results suggested that Si amendment could increase the activity of antioxidant enzymes of eggplant leaves, thereby increased the resistance to R. solanacearum.
