作物根际解磷真菌YTY的离子束诱变及其解磷机理探讨

为筛选并构建高效的作物根际解磷真菌,探讨解磷真菌的解磷机理,本研究从小麦和棉花根际土壤中分离筛选了一株高解磷能力的真菌YTY,对其离子束诱变的最佳条件进行探讨,进一步构建YTY的高效解磷突变菌,并从有机酸角度研究YTY的解磷机理。结果表明,从作物根际土壤分离的解磷真菌YTY具有较高的解磷能力,形态学和ITS鉴定表明该菌为草酸青霉;YTY的最佳诱变条件为30 keV和1×10¹⁵ ions·cm^-2,利用该诱变条件获得了3株高效解磷突变株,即p-1-1、p-1-2、p-1-3,解磷能力分别较出发菌株YTY提高了56.88%、42.26%和32.15%;YTY培养液(5 d)的pH值为2.5,离子色谱法测得其中含有3种有机酸,即乳酸、乙酸和草酸,同时测得3株突变菌培养液的pH值为2.0,显著低于出发菌株YTY,且乳酸、乙酸、草酸和总酸含量均显著高于YTY,表明有机酸是YTY解磷的重要物质,且乳酸、乙酸、草酸是YTY解磷的主要有机酸。本研究结果为解磷真菌的离子束诱变选育提供了参考,并为真菌YTY解磷机理的探明及开发应用提供了理论依据和生物材料。

Ion Beam Mutagenesis and Phosphate Solubilizing Mechanism on PSF YTY Isolated From Rhizospheric Soil

To screen efficient Phosphate Solubilizing (PS) fungi and mutants as well as exploring their PS mechanism, in this article, the fungus YTY with PS ability was isolated from rhizosphere of wheat and cotton. Followed by low energy ion irradiation basing on optimum irradiational condition, the mutants of YTY with highly efficient PS ability were acquired. In addition, the PS mechanism of YTY was explored based on organic acids as products. Our results showed that YTY strain isolated from rhizosphere had a PS capacity of 186.4 mg·L^-1, and was identified as Penicillium oxalicum according to its morphology and ITS amplicon sequencing. Three efficient PS mutants p-1-1, p-1-2 and p-1-3 were obtained at the best mutagenic dose of 30 keV and 1×10¹⁵ ions·cm^-2. The PS ability of three mutants were 291.8, 264.6 and 245.8 mg·L^-1 for p-1-1, p-1-2 and p-1-3, respectively, which were 56.88%, 42.26% and 32.15% higher than that of YTY strain. The concentration of lactic, acetic, and oxalic determined by ion chromatography were 0.0401, 0.0384, and 0.0643 mmol·L^-1, respectively in YTY medium cultured for five days (pH 2.5). For three mutants of p-1-1, p-1-2 and p-1-3, the lactic, acetic, oxalic, and total acid contents were 0.0643, 0.0484, 0.0945, 0.2072; 0.0927, 0.0623, 0.0634, 0.2184 and 0.0523, 0.0438, 0.0637, 0.1598 mmol·L^-1, respectively, which were significantly higher than that of YTY (P<0.05). The media pH of mutants (pH 2) were also significantly lower than that of YTY (P<0.05). It is suggested that YTY solubilized phosphate mainly by producing organic acids, such as lactic, acetic and oxalic. This study could guide us the breeding of efficient PS mutants by ion beam, build up a theoretical basis on the detection of the PS mechanism, and provide biological materials for development and application for PS fungi.