产ACC脱氨酶细菌与AM真菌互作对茶树的促生效应研究

Tea as an important cash crop, is widely planted and distributed in China. However, many tea gardens are confronted with soil degradation and a variety of adversity stress at present, which seriously affected the normal growth of tea. As the important members of soil microorganism, ACC deaminase-producing bacteria (ADPB) and arbuscular mycorrhizal (AM) fungi received much concerns for improving soil fertility and promoting plant growth. In the present study, we will screen ADPB and AM fungi in the rhizosphere soils of tea respectively, optimize the conditions of enzyme production by ADPB, and then cloning and characterization of ACC deaminase gene from ADPB. Then, the synergistic effects between ADPB and AM fungi on the growth of tea will be studied under dual-inoculation, and the mechanisms will be investigated by the changes of photosynthetic characteristics, architecture and activity of root, soil element content, structure of soil microbial community, activity of soil enzyme, colonization rate and quantity of spore of AM fungi. The present study will enrich agro-forestry microbial resources, and contribute to the development and application of composite fertilizer for tea, which could provide important theoretical basis and technical support to prevent soil degradation and improve yield and quality of tea, and play important role in protecting soil environment of tea garden and promoting the healthy growth of tea.

茶树栽培面积大、分布广，是我国重要的经济作物之一。目前，许多茶园面临地力衰退和多种逆境的胁迫，严重影响了茶树的正常生长。作为土壤微生物的重要成员，产ACC脱氨酶细菌和AM真菌在改善土壤肥力和促进植物生长发育等方面的功能备受关注。本研究拟从我国茶树根际分离和筛选优良的产ACC脱氨酶细菌和AM真菌，在优化产ACC脱氨酶细菌产酶条件、克隆脱氨酶基因及其功能解析的基础上，将两者双接种于茶树苗，研究互作模式下对茶树的促生效应，并通过茶树光合特征、根系构型与活力、土壤肥力、土壤微生物群落结构以及菌根侵染率与产孢量的变化，探索产ACC脱氨酶细菌与AM真菌互作对茶树的促生机制。本项研究将丰富我国农林业微生物种质资源，推动茶树复合菌肥的开发与应用，为预防茶园地力衰退和提高茶叶产量与品质提供重要的理论依据和技术支撑，对保护我国茶园土壤环境，促进茶树健康生长具有重要的指导意义。

茶树栽培面积大分布广，是我国重要的经济作物之一。目前，许多茶园面临地力衰退和多种逆境的胁迫，严重影响了茶树的正常生长。作为土壤微生物的重要成员，产ACC脱氨酶细菌和AM真菌在改善土壤肥力和促进植物生长发育的研究备受关注。.（1）本研究从茶树根际土中获得了10株产ACC脱氨酶细菌，其中一株鉴定为粘质沙雷氏菌（Serratia marcescens）JW-CZ2菌株产ACC脱氨酶能力最强，其酶活性为1.08U·mg-1，该菌株还具有较强的产IAA的能力和溶磷能力，对茶树的生长具有显著的促进作用。.（2）JW-CZ2菌株基因组全长为4934394bp，（G+C）59.82%，不包含质粒，共有4672个CDS，4197个具有编码已知功能的蛋白质，475个编码蛋白质的功能未知。在4179个已知功能蛋白中，NR、Swiss-prot、COG、KEGG和GO数据库中分别注释了3793个、3960个、2937个、2300个和4164个。.（3）在安徽茶区，AMF 能够侵入茶树根系形成典型的共生体，侵染率在36%～95%，侵染级数均在3 级以上，侵染强度大。从安徽茶树根际土中共鉴定出8属36种 AMF，其中缩管柄囊霉是优势种，网状球囊霉、刺无梗囊霉、孔窝无梗囊霉、詹氏无梗囊霉、双网无梗囊霉和凹坑无梗囊霉是常见种。.（4）JW-CZ2菌株优化后的培养基配方：蔗糖10.81 g·L-1、蛋白胨 9.54 g·L-1、乙酸铵 0.40 g·L-1、NaCl 5.08 g·L-1、磷酸二氢钾 1.00 g·L-1，pH 7.2。培养条件为：接种量1.00%，转速200 r·min-1，温度28℃，培养24 h，经验证与模型预测值0.904较为接近。.（5）无论JW-CZ2或Fc单接种，还是JW-CZ2与Fc双接种均能明显促进茶树的生长且双接种效应显著优于各单接种。与CK相比，双接种6个月后，JW-CZ2+Fc双接种茶树的苗高和地径增长了21.49%和13.55%，菌根侵染率提高了136.11%，叶绿素a、叶绿素b和总叶绿素含量分别增长了22.41%、13.11%和17.48%。. 本项研究丰富了我国农林业微生物种质资源库，有助于茶树复合菌肥的开发与应用，为预防茶园地力衰退和提高茶叶产量与品质提供重要的理论依据和技术支撑，对保护我国茶园土壤环境，促进茶树健康生长具有重要的指导意义。