不同供磷量对玉米根系与土壤微生物互作及吐丝后地上部碳磷分配的影响

发布时间：2018-01-21 08:57

本文关键词： 土壤临界磷浓度磷再转移菌根真菌根系转录组微生物群落结构玉米　出处：《中国农业大学》2017年博士论文　论文类型：学位论文

【摘要】：确定合理的磷肥施用量及土壤有效磷浓度对生产中磷肥减施增效,发挥作物自身及土壤微生物的生物学潜力,保证农业生态系统可持续发展具有重要意义。本研究以玉米为材料,在中国农业大学上庄试验站通过多年田间定位试验,确定了保证玉米高产的磷肥临界施用量及相应的土壤临界磷浓度;研究了不同供磷量对玉米吐丝后地上部磷再转移、分配及叶/穗碳水化合物浓度的影响;应用分子生物学方法,比较研究了不同供磷量(0-300 kg/ha)及土层(0-20 cm,20-40 cm)间玉米根中菌根真菌群落结构和供磷潜力的差异;采用RNA-Seq、16S、ITS测序技术以及土壤辐照灭菌技术,比较了缺磷和充足供磷下,玉米轴根和侧根转录组、微生物群落结构以及微生物对玉米生长的作用。主要结果如下:1)保证玉米高产的当地磷肥(P205)临界施用量为75-100 kg/ha,对应的0-20 cm 土层Olsen-P浓度为6-10 mg/kg。超过临界值后,继续增加施磷量不会增加玉米产量,导致磷肥利用率下降。20-40 cm土层的Olsen-P浓度在充足甚至过量施磷条件下仍维持在3-6 mg/kg的亏缺水平。适宜施磷量的玉米地上部总磷浓度从八叶期(生物量为2 t/ha左右)的3 mg/g降低至吐丝期(生物量为8 t/ha)后的1.6mg/g,之后保持不变至成熟。2)缺磷显著提高玉米吐丝后早期下部叶片的磷再转移效率,对茎和上部叶片磷再转移效率以及成熟时的磷收获指数无显著影响。缺磷未显著影响玉米吐丝后穗位叶光合速率,但促进吐丝后早期叶/穗中淀粉合成。乳熟期玉米体内的磷再转移以及叶/穗碳水化合物浓度均不受供磷水平影响。3)玉米根系菌根真菌侵染率、丛枝丰度、菌根真菌酸性/碱性磷酸酶活性以及根系ZmPht1;6(菌根真菌侵染诱导表达的磷转运蛋白基因)和ZmCCD8a(独角金内酯合成基因)相对表达量随施磷量增加而显著降低。当施磷量超过75-100 kg/ha时均达到最低值,并且不再随施磷量增加而变化。20-40 cm 土层玉米根系中上述指标所反映的菌根真菌供磷潜力明显高于0-20 cm 土层的根系。与上述指标的变化不同,玉米根中菌根真菌OUT数目和香农指数在不同磷水平或土层间均无显著差异,但真菌群落组成和OUT相对丰度在供磷水平间有显著差异,群落组成在土层间没有显著差异。4)玉米轴根和侧根转录组以及真菌群落结构有明显差异,并且差异大于不同供磷水平造成的差异。在转录水平,充足供磷时,轴根细胞壁代谢、次生代谢及生物胁迫防御代谢显著弱于侧根。缺磷胁迫导致玉米轴根、侧根大量基因表达上调,轴根中差异表达基因数目显著多于侧根且主要富集于生物胁迫防御代谢。菌根真菌主要侵染侧根而不是轴根,缺磷胁迫主要改变侧根中的真菌群落结构。5)盆栽结合土壤辐照灭菌研究表明,缺磷土壤灭菌进一步抑制玉米生长并导致植株极度缺磷,而充足供磷土壤灭菌则促进玉米生长。根系转录组分析结果表明,土壤灭菌导致根系大量基因表达下调。充足供磷土壤灭菌后表达显著下调的基因富集于生物胁迫防御、蛋白水解、几丁质代谢、氧化还原等生物过程。缺磷土壤灭菌后表达显著下调的基因富集于DNA复制,脂肪酸代谢、细胞壁合成等过程。缺磷和充足供磷时根中细菌和真菌群落结构无显著差异。综上,合理的磷肥施用不仅能够获得高产,同时能够大幅度提高磷肥利用率。缺磷及过量施磷均不能提高磷收获指数。在充足甚至过量施磷条件下,20-40 cm 土层玉米根系中菌根真菌供磷潜力显著高于0-20 土层的根系。缺磷时土壤微生物帮助玉米获取磷的有益作用大于有害作用,而供磷充足时则相反。充足供磷时,侧根中真菌侵染及生物胁迫防御代谢均强于轴根,缺磷胁迫主要改变侧根中真菌群落结构,诱导轴根生物胁迫防御代谢。说明供磷既可以影响玉米轴根、侧根的功能分离,也能影响土壤微生物提高土壤磷利用的生物学潜力。侧根作为植物主要的吸收养分和水分的部位,被真菌侵染的程度和真菌的群落结构更容易受供磷水平的影响,而轴根生物胁迫防御代谢的显著上调可以尽可能减少有害微生物的危害。
[Abstract]:To determine the application efficiency of the production of phosphate fertilizer and phosphate fertilizer reduced soil available phosphorus concentration reasonably, crop and soil microorganisms play their biological potential, is an important guarantee of sustainable development of agro ecosystem. In this study, corn as the material, through years of field experiment station in China Agricultural University on the test, confirming the critical application amount of phosphate fertilizer high yield of maize and the corresponding critical soil phosphorus concentration; of different phosphorus content on Maize shoot p re transfer, distribution and effect of ear leaf / carbohydrate concentration; with molecular biology methods, comparative study of different phosphorus content (0-300 kg/ha) and soil layer (0-20 cm, 20-40 cm) difference among the mycorrhizal fungi community structure and potential for phosphorus in maize roots; using RNA-Seq, 16S, ITS sequencing technology and soil irradiation sterilization technology, compares the phosphorus deficiency and sufficient supply of phosphorus, Corn root and root transcriptome, microbial community structure and microbial effects on the growth of maize. The main results are as follows: 1) to ensure the local fertilizer high yield of Maize (P205) critical application amount was 75-100 kg/ha, the corresponding 0-20 cm soil Olsen-P concentration was 6-10 mg/kg. exceeds the critical value, continue to increase the amount of phosphorus does not increase maize the yield, resulting in Olsen-P phosphate fertilizer utilization rate of decline in.20-40 cm soil layer under the condition of adequate or excessive P remained at 3-6 mg/kg level. The suitable amount of phosphorus deficiency of maize aboveground total phosphorus concentration from eight leaf stage (biomass is about 2 t/ha) 3 mg/g reduced to silking (biomass for 8 t/ha) after 1.6mg/g, after unchanged to mature.2) P significantly increased maize early lower leaf phosphorus transfer efficiency, phosphorus harvest index of stem and leaf phosphorus transfer efficiency and when mature No significant effect of phosphorus deficiency did not significantly affect maize ear leaf photosynthetic rate, but the promotion of early leaf / ear after silking in starch synthesis. In milk stage corn phosphorus transfer and leaf / panicle carbohydrate concentrations were not affected by P level.3) maize root arbuscular mycorrhizal fungi colonization rate. The abundance of mycorrhizal fungi, acid / alkaline phosphatase activity and root ZmPht1; 6 (phosphate transporter gene expression induced by mycorrhizal fungi (ZmCCD8a) and strigolactone synthetic gene) expression significantly decreased with the increase of phosphorus fertilizer application. When phosphorus was more than 75-100 when kg/ha reached the lowest value, and is no longer with the application the amount of P increases the index of.20-40 mycorrhizal fungi cm soil of maize root of P potential was significantly higher than that in 0-20 cm soil layer. The root changes with the above index of different number of mycorrhizal fungi in roots of maize and sweet OUT The agricultural index showed no significant difference in different phosphorus levels or layers, but OUT fungal community composition and relative abundance of significant differences in P level, the community composition.4 has no significant difference in the soil) have obvious difference of maize root and root transcriptome and fungal community structure, and the difference is greater than the difference caused by different phosphorus levels. At the transcriptional level, adequate supply of phosphorus, root cell wall metabolism, secondary metabolism and biological stress defense metabolism was significantly weaker than that of lateral roots. Phosphorus deficiency stress leads to upregulation of lateral root of corn, a large number of genes differentially expressed in root, lateral root and the number of genes significantly more than mainly enriched in biological stress defense metabolism. Mycorrhizal fungi mainly infect rather than root root, phosphorus stress.5 fungal community structure changes in the main root) of soil pot irradiation showed that phosphorus deficient soil sterilization to further suppress the jade The growth of plants and lead to extreme M P, and adequate phosphorus soil sterilization promote maize growth. Root transcriptome analysis results showed that soil sterilization resulted in down-regulation of gene expression. A large number of roots significantly down regulated genes enriched in biological stress defense, protein hydrolysis, chitin metabolism of adequate supply of phosphorus in soil after sterilization, redox and other biological process. Pdeficient soil sterilization significantly down regulated genes enriched in DNA replication, fatty acid metabolism, cell wall synthesis process. The phosphorus and phosphorus supplying adequate root bacterial and fungal community structure have no significant difference. In conclusion, the reasonable application of phosphate fertilizer can not only get high yield, and can greatly improve the utilization ratio of phosphate fertilizer. Phosphorus deficiency and excess phosphorus can increase phosphorus harvest index. In adequate or excessive phosphate fertilizer conditions, 20-40 cm soil of maize root mycorrhizal fungi were significantly higher than that in 0-20 soil phosphorus supply potential The beneficial effect of phosphorus in roots. When soil microbes help corn phosphorus acquisition is greater than the harmful effect, and phosphorus sufficient opposite. Adequate supply of phosphate, the plant fungal infection and biological stress defense Xie Junqiang in root, phosphorus stress change in main root fungal community structure, metabolism of individual biological stress induced defense that P can affect maize root, root separation function, also can improve the effect of soil microbial biological potential of soil phosphorus utilization. As the plant root absorption of nutrients and water are the main parts of the community structure, and the degree of fungal infection are more easily affected by phosphorus levels, and increased defensive metabolism individual biological stress can minimize the hazards of harmful microorganisms.

【学位授予单位】：中国农业大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：S513

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