| Summary: | 碩士 === 國立彰化師範大學 === 生物學系 === 106 === Phosphorus (P) is an important macronutrient required for plant growth. The dominant form of phosphorous and the form most readily taken up by roots is the monovalent orthophosphate anion H2PO4− and HPO42−. However, the inorganic phosphate is easily combined with the elements of calcium, iron and aluminum in the soil solution. About 70% to 99% of the phosphate fertilizer will be precipitated in the form of minerals, and can not be absorbed by plants. Fortunately, phosphate solubilizing microbes (PSM) possess the ability to solubilize sparingly soluble phosphates in vitro by secreting low molecular weight organic acids, then increasing phosphorus amount in soil. However, there is not much research on the phosphate solubilizing fungi (PSF) in Taiwan. In previous study by us, phosphate-solubilizing yeasts were isolated on Drosera spatulata plant leaves in New Taipei City. Therefore, we aim to study the phosphate solubilization and plant growth promotion of these yeasts by inoculation the plants with yeasts. The plants we used includ Arabidopsis thaliana and Solanum Lycopersicum cv. Saint-Tom. Here, our study show: JYC100 promotes plant growth on specific conditions (Pi deficiency but with insoluble phosphate) medium and soil pots. From the appearance, fresh weight and cellular Pi content, it can be observed that plants cocultured with JYC100 are larger, heavier and with more phosphorus content. The results indicate the ability of JYC100 to promote P uptaking by solubilizing P compounds. In addition to the role of phosphorus solubilization, auxin secreted from yeast brings other benefits. GUS histochemical staining of root specimens revealed that both yeasts (JYC100 and JYC104) can promote plant lateral root growth, but summing of the previous experiments can prove again that JYC100 helps plants grow mainly because of the ability to dissolve phosphorate. In addition, analysis of the histochemical GUS assays of phosphate starvation-induced (PSI) genes showed that the expression of the PSI genes (PT2 and PLDZ2) is decreased in the plants cocultured with JYC100. These results thus reflect the role of JYC100 in solubilizing P and increasing the nutrient supply of plants to help plants avoid phosphorus deficiency. Our study results highlight the potential use of yeasts as plant biofertilizers under field condition.
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