玉米根际微生物氮磷转化的功能基因组学分析

Functional Genomics Analysis of Nitrogen and Phosphorus Transformation in Maize Rhizosphere Microorganisms

化肥减量增效是保障农业生态环境安全的重要基础.微生物是调控土壤氮磷循环的关键驱动力,研究根际微生物氮磷转化功能可以为进一步提高土壤氮磷利用率提供微生物学调控途径.基于3种典型农田土壤(黑土、潮土和红壤)的田间微区试验,利用宏基因组测序技术研究玉米根际微生物在土壤氮磷转化过程中功能基因的差异及调控因子.结果表明,根际微生物功能多样性受土壤类型影响,黑土和潮土的根际微生物功能多样性主要受含水量和养分含量的影响,红壤受全磷(TP)和速效磷(AP)影响.在土壤氮转化方面,编码氮转化过程通路中相关酶的基因丰度以脲酶基因(ureC)和葡萄糖脱氢酶基因(gdh)丰度最高,分别为7.25×10^(-5)~12.88×10^(-5)和4.47×10^(-5)~7.49×10^(-5).同化性硝酸盐还原的功能基因在红壤中总丰度要高于黑土和潮土,其它过程相关酶的功能基因总丰度以潮土最高.编码氮代谢过程相关酶的功能基因丰度主要受土壤细菌丰富度、全钾(TK)和TP含量的驱动.在土壤磷转化方面,催化有机磷矿化的碱性磷酸酶基因(phoD)数目为1093个,酸性磷酸酶基因(PHO)数目为42个.phoD丰度高出PHO丰度2个数量级,此外,同种土壤类型下施肥对phoD和PHO丰度没有显著影响.随机森林分析表明phoD和PHO丰度均受土壤水分、有机质(OM)和全氮(TN)显著影响,但AP含量对PHO丰度影响最大.从功能基因组水平研究了玉米根际微生物的氮磷转化特征,为利用微生物功能提高农田生态系统氮磷利用率提供了科学依据.

Fertilizer reduction and efficiency improvement is an important basis for ensuring the safety of the agricultural ecological environment.Microorganisms are the key driving force for regulating the soil nitrogen and phosphorus cycle.Studying the nitrogen and phosphorus transformation function of rhizosphere microorganisms can provide a microbiological regulation approach for further improving the use efficiency of soil nitrogen and phosphorus.Based on the field micro-plot experiments of three typical farmland soils(phaeozem,cambisol,and acrisol),metagenomic sequencing technology was used to study the differences in functional genes and regulatory factors of maize rhizosphere microorganisms during soil nitrogen and phosphorus transformation.The results showed that the functional diversity of maize rhizosphere microorganisms was affected by soil type.The functional diversity of rhizosphere microorganisms in phaeozem and cambisol was mainly affected by water content and nutrient content,and that in acrisol was affected by total phosphorus(TP)and available phosphorus(AP).For soil nitrogen transformation,the gene abundance of related enzymes in the pathway of nitrogen transformation was the highest in the urease gene(ureC)and glucose dehydrogenase gene(gdh),which were 7.25×10^(-5)-12.88×10^(-5) and 4.47×10^(-5)-7.49×10^(-5),respectively.The total abundance of assimilatory nitrate reduction functional genes in acrisol was higher than that in phaeozem and cambisol,and the total abundance of functional genes related to other processes was the highest in cambisol.The abundance of functional genes encoding enzymes related to nitrogen metabolism was mainly driven by soil bacterial richness,total potassium(TK),and TP.For soil phosphorus transformation,the number of alkaline phosphatase genes(phoD)catalyzing organic phosphorus mineralization was 1093,and the number of acid phosphatase genes(PHO)was 42.The abundance of phoD was two orders of magnitude higher than that of PHO.In addition,fertilization had no significant effect on the abundance of phoD and PHO in the same soil type.Random forest analysis showed that the abundances of phoD and PHO were significantly affected by soil moisture,organic matter(OM),and total nitrogen(TN),but AP content had the greatest impact on PHO abundance.These results clarified the nitrogen and phosphorus transformation characteristics of maize rhizosphere microorganisms at the functional genomic level and enriched the molecular biological mechanism of the microbial nitrogen and phosphorus transformation function.