哈茨木霉菌对砂糖橘苗木的促生作用及差异代谢物的分析

Promotive effect of Trichoderma harziana on citrus nursery plants and differential metabolites

[目的]利用非靶向代谢组学探究哈茨木霉菌处理后砂糖橘叶片代谢谱的差异,以及哈茨木霉菌对砂糖橘苗木的促生作用。[方法]通过不同浓度的哈茨木霉菌水溶液灌根处理,以浇灌等量清水为对照(CK),对枳砧砂糖橘苗木的生长指标、矿物元素含量、叶绿素含量及非靶向代谢物进行检测,与mzCloud、mzVault和Masslist数据库进行比对,并分析代谢组数据。[结果](1)哈茨木霉菌A处理(1.33 g·L^(-1)灌根8次+2.00 g·L^(-1)灌根7次)灌根后,砂糖橘叶面积比CK显著增加,且新根发育茂盛。(2)A处理和B处理(3.33 g·L^(-1)灌根8次+4.00 g·L^(-1)灌根7次)灌根后,叶片中叶绿素b含量和根冠截面积均高于CK。(3)A处理能显著提高叶片中P、Ca、Mg、Fe、Zn等5种元素的含量,B处理能显著提高叶片中P、Ca、Mg、Zn等4种元素的含量。(4)非靶向代谢物分析表明,阳离子分析中,A处理与CK的差异代谢物有20种,其中8种代谢物上升、12种代谢物下降;阴离子分析中,A处理与CK的差异代谢物有18种,其中6种代谢物上升、12种代谢物下降。(5)通过KEGG数据库对差异代谢物进行通路富集表明,阳离子分析中A处理与CK的差异代谢物分布在146条代谢途径中,有3条KEGG路径被富集(P<0.05),包括鞘脂代谢、碳青霉烯生物合成和生物素代谢;阴离子分析中,A处理与CK的差异代谢物分布在141条代谢途径中,有4条KEGG路径被富集(P<0.05),包括缬氨酸、亮氨酸和异亮氨酸的降解,丙酸盐代谢,花青素生物合成以及甘氨酸、丝氨酸和苏氨酸的代谢。[结论]揭示了哈茨木霉菌处理对砂糖橘体内次生代谢物的影响,为了解该菌促进柑橘生长和提高抗病性的机理提供了理论依据。

[Purpose]The study aimed to evaluate the promotive effect of Trichoderma harziana on citrus seedling using non-targeted metabolomics analysis.[Method]T.harziana treatments of different concentration were set up on Citrus reticulata cv.‘Shatangju’grafted on Poncirus trifoliata:treatment A included irrigation of 1.33 g·L^(-1) T.harziana aqueous solution for 8 times and irrigation of 2.00 g·L^(-1) T.harziana solution for 7 times,treatment B included irrigation of 3.33 g·L^(-1) T.harziana solution for 8 times and irrigation of 4.00 g·L^(-1) T.harziana solution for 7 times,and the control was irrigated with the same amount of water at the same frequencies.The growth indexes and the contents of chlorophyll and mineral elements were measured;after screening the differential metabolites,non-targeted metabolomics analysis was performed in comparison to standard databases of mzCloud,mzVault and Masslist.[Result](1)Leaf area was enhanced significantly under treatment A compared with that of the control,and young roots also flourished.(2)The foliar content of chlorophyll B and the cross-sectional area of root crown under treatments A and B were higher than the counterparts in the control.(3)The foliar contents of P,Ca,Mg,Fe and Zn were increased significantly under treatment A,while only the contents of P,Ca,Mg and Zn were increased under treatment B.(4)Non-targeted metabolomics analysis identified 20 types of differential metabolites by cation analysis under treatment A,among which 8 kinds of metabolites were up-regulated and 12 kinds were down-regulated.While the types of differential metabolites were decreased to 18 by anion analysis,with 6 types up-regulated and 12 types down-regulated.(5)KEGG pathway enrichment analysis showed that the differential metabolites were distributed in 146 metabolic pathways under treatment A,among which 3 pathways were enriched(P<0.05),comprising pathways regulating sphingolipid metabolism,carbapenem biosynthesis and biotin metabolism;anion analysis showed that the differential metabolites were distributed in 141 metabolic pathways under treatment A,among which 4 KEGG pathways were enriched,including the pathways regulating the degradations of valine,leucine and isoleucine,propanoate metabolism and anthocyanin biosynthesis.[Conclusion]The study revealed the effects of T.harziana on the secondary metabolites in citrus,which provided a theoretical basis for the application of T.harziana agent for the improved growth and disease resistance of citrus plants.