Effects Of Transgenic BADH Soybean On The Phosphorous Transformation In Saline-alkaline Soil

Betaine-aldehy dedehydrogenase (BADH) is a key gene during a synthesizing betaine processof higher plants. Transgenic BADH soybean which put base aldehyde dehydrogenase gene (BADH)into the cultivated soybean Heinong35could present a well growth on saline-alkali soil.However,the releasing matters of transgenic soybean with gene BADH probably effect a change of soilecological system. It is speculated that the metabolism of soybean could be influenced by BADH,which changes compositions and quantites of rhizospheric secretion, and effect the diversity offunctional bacteria resulting in the phosphorus converting and ecological process changed.In order to approve the hypothesis, western saline-alkali soil of Heilongjiang Province, and5kinds of soybean are utilized, including transgenic soybean with gene BADH, non-transgenicsoybean Heinong (HN-35), wild soybean (YS-21) and cultivated soybean Kangxianwang (K) andHefeng50(HF-50) as materials. The research applies both field experiment and pot experiment toanalyze the variation of rhizospheric secretion. Futhermore, molecular techniques polymerasechain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) technique is employed toinvestigate the variation of functional bacteria diversity, which having relationships with the Pconverting process. The relationships between functional bacteria structure and the variation ofecological function about phosphorus transformation are also discussed. The research wouldinvestigate mechanism of functional bacteria structure and ecological function are influnced bytransgenic soybean with gene BADH, which could provide theorical references for ecologicalsecurity assessment of saline-alkali soil in fulture. The paper drawed an inference followingconclusions from analysis above:1.Effects of transgenic BADH soybean on components and content in root exudatesThe H+secretion of SRTS (0.049μmol g-1dry root h-1) was highest, compared with K, HN-35,Y-21and HF-50, SRTS increased H+secretion by14.65%,48.20%,40.43%and63.16%respectively. Compared to other soybean varieties, SRTS had stronger ability to release H+, whichcan effectively acidified soil to adjust the pH of the rhizospheric soil and improve saline-alkalineenvironment.Compared with HN-35, SRTS changed compositions and quantites of rhizospheric secretion.Five kinds of oganic acids were detected in SRTS root exudates and six kinds of oganic acids weredetected in HN-35root exudates. Tartaric acid and malonic acid were not ingredients of root exudates, but D-(+)-malic acid was a specific organic acid component of SRTS. Citric acid andacetic acid content of SRTS in root exudates was higher than that of other varieties soybeans. Thecontent of oxalic acid and succinic acid of SRTS and HN-35in root exudates had difference but itwas too small to reach the significant level. We analysis the total content of organic acid,compared with HN-35, SRTS had less type of organic acid than HN-35, but the content wassignificantly higher than that of HN-35.Kinds of amino acid in SRTS root exudates were little changed, but the content of it werequite different. Thirteen kinds of amino acid were detected from eighteen kinds of amino, of whichthe aspatic acid secretion was the most. In addition, SRTS increased the content of glutamic acid,asparagine, tryptophan, glutamine, arginine, tryptophan, phenylalanine and lysine in SRTS rootexudates were increased by102.79%、55.43%、34.28%、33.79%、78.17%、63.29%、117.84%and147.62%compared to HN-35. The content of alanine, glycine, valine and leucine of amino acid ofSRTS root exudates were significantly higher than HN-35, Y-21and HF-50, increased by37.93%,17.63%and131.68%respectively, but that of SRTS and K were difference but if was too small toreach the significant level.There was not significant differences in total soluble sugar content of SRTS and othersoybean, only increased YS-21by78.52%. To a certain extent, there were differences in thecompounds and content of carbohydrate. Ten kinds of carbohydrate were detected in all soybeanroot exudates, and that included inositol, erythritol, glycerol, glucose, fructose, ribose alcohol,sucrose, maltose, glucose, Arabia sugar and galactose. As a whole, the trend is consisten. Thatsecretion of ribose were highest, secretion of sucrose were least. Compare with HN-35, SRTSincreased content of erythritol, glycerol, fructose, glucose, Arabia sugar by18.65%、17.26%、136.06%and13.14%. There were not significant differences between ribitol, fructose, glucose andgalactose content of SRTS and HN-35, but the content of nositol and maltose in SRTS rootexudates was significantly lower than that of HN-35.2. Effects of transgenic BADH soybean on phosphate abailability in rhizospheric soil.SRTS had effects on the available phosphorus in rhizospheric soil, but the effect is period,SRTS could promote the content of available phosphorus in the flowering and fruiting period, thatof SRTS and HN-35, HF-50had not difference in seed-filling stage significantly, but significantlyhigher than that of Y-21and K, increased by4.32%and11.15%respectively. Mature SRTSavailable P of rhizospheric soil is lower than that of HN-35, but significantly higher than that ofother varieties soybean.SRTS had a promoting effect on soil organic phosphorus. According to the average content oforganic phosphorus SRTS was significantly higher than that of other varieties soybean. SRTSpromote the maturity of organic phosphorus in rhizospheric soil certainly. Effect of SRTS oninorganic phosphorus was period. SRTS had strongest activation ability of inorganic phosphorus inrhizospheric soil during flowering period, and had no significant difference with other species soybean in other periods.Compare with HN-35, SRTS had a promoting effect on microbial biomass phosphorus in theseedling, podding and mature period. SRTS could promote the content of microbial biomasscarbon. In the seedling period, flowering period, fruiting period and mature period, SRTS hadhigher capacity of promoting microbial biomass carbon in rhizospheric soil than HN-35. SRTSreduced the microbial biomass C/P in the rhizospheric soil.3. Effects of transgenic BADH soybean on ecology function of phosphate transformation inrhizospheric soil.Effect of SRTS on the acid phosphatase activity showed that there is a promoting effect on theacid phosphatase activity in the flowering and fruiting period of soybean seedling. In the poddingperiod and mature period, SRTS reduced the activity of acid phosphatase. SRTS had a significantpromoting effect on the activity of neutral phosphatase. Compared with HN-35, Y-21, K and HF-50SRTS, SRTS increased neutral phosphatase activity in rhizospheric soil by26.42%,203.92%,14.15%and32.94%, SRTS had little effect on the activity of alkaline phosphatase in rhizosphericsoil, in addition to podding period, there was not significant difference between SRTS and parentalnon-transgenic soybean HN-35of alkaline phosphatase activity in rhizospheric soil. Thecorrelation analysis showed that, there was the most relation between neutral phosphatase activityand phosphorus availability.SRTS could reduce the pH of rhizospheric soil, which directly affect the soil microbialcommunity types, quantity and activity. SRTS increased the number of phosphate-mineralizationbacteria and phosphate-solubilizing bacteria, and promoting the transformation capacity of organicphosphorus and inorganic phosphorus transformation strength intensity, correlation analysisshowed that the quantity of phosphate-mineralization bacteria and organic phosphorustransformation strength, phosphate-solubilizing bacteria and inorganic phosphorus transformationwere significantly positive related.4. Effects of transgenic BADH soybean on the biodiversity of phosphate bacteria.The diversity analysis indicated that Shannon-Wiener diversity indexes (Dsh) and evennessindexes (Jsh)related to phosphate-mineralization bacteria of SRTS in rhizospheric soils were allhigher than those of near-isogenic counterparts (HN-35), but the number of bands were lower thanHN-35. Shannon-Wiener diversity indexes (Dsh) and evenness indexes (Jsh)related tophosphate-solubilizing bacteria of SRTS in rhizospheric soils were all lower than those ofnear-isogenic counterparts (HN-35), but the number of bands were higher than HN-35. Theprincipal component analysis demonstrated that the compositions of phosphate-mineralizationbacteria communities of in SRTS rhizospheric soil were similar to those of phosphate-solubilizingbacteria in SRTS and HN-35rhizospheric soil, but they were different from thephosphate-mineralization bacteria communities in HN-35rhizospheric soil. SRTS inhibited somegroups of phosphate-mineralization bacteria communities, such as groups represented by bands l, m, n, q, u, v and w, however, promoted the other groups, such as groups represented by band a, g,o, p, t. At the same time, SRTS inhibited some groups of phosphate-solubilizing bacteriacommunities, such as groups represented by bands C, K, L and w, however, promoted the othergroups, such as groups represented by band D, F, J, Q, R, S. In this research,phosphate-mineralization bacteria in rhizospheric soil had been recorded and classitied in theprevious literature, it mainly belong to Bacillus, Pseudomonas, Enterobacter, Flavobacterium andSalmonella, compared to HN-35, Flavobacterium and Salmonella were only belonging to SRTS.Phosphate-solubilizing bacteria mainly belong to Bacillus, Pseudomonas, Enterobacter, andCitrobacter, compared to HN-35, Citrobacter were only belonging to SRTS. Our results indicatedthat SRTS reduced the diversity of PMB, promting the diversity of PSB, changing phosphorusbacteria community structure and affecting the growth and distribution of some groups ofphosphorus bacteria in rhizospheric soil to some extent.