■内生菌是健康植物的定殖者,它们通常表现出生物防治活性,如减少植物病害的发生和促进植物生长。从马铃薯植株的根中分离出内生细菌卤族芽孢杆菌Q2H2(Q2H2),发现对病原真菌有拮抗作用。
■通过形态学观察确定了Q2H2,生理生化鉴定,和16SrRNA基因序列分析。使用全基因组测序和比较基因组分析来分析与抗真菌和生长促进作用相关的基因。最后,我们使用盆栽实验分析了Q2H2在马铃薯植株中的促生长和生物防治活性。
■拮抗作用和非挥发性物质平板试验表明,Q2H2对尖孢镰刀菌有较强的拮抗作用,镰刀菌公社,禾谷镰刀菌,短镰刀菌,枯丝核菌和枯萎病菌。平板试验表明,Q2H2具有产生蛋白酶的能力,纤维素酶,β-1,3-葡聚糖酶,溶解的有机磷酸盐,铁载体,吲哚-3-乙酸(IAA),氨和固定氮。在不同形式的非生物胁迫下,Q2H2的合适生长范围为pH5-9,温度为15-30°C,和1-5%的盐浓度。虽然全基因组测序,我们获得了约4.16MB的测序数据,包括4,102条编码序列.我们预测了10个与拮抗和促进生长相关的次级代谢产物基因簇,包括五种已知的表面活性蛋白,杆菌烯,芬霉素,杆菌素,杆菌素,平均核苷酸同一性和比较基因组分析显示,Q2H2是盐芽孢杆菌。通过基因功能注释,我们分析了Q2H2基因组中与拮抗作用和植物生长促进相关的基因。这些包括参与磷酸盐代谢的基因(pstB,pstA,pstC,和pstS),固氮(nifS,NifU,萨拉,和后缀),氨生产(gudB,rocG,美国国家航空航天局,和nasE),铁载体生产(fhuC,fhuG,fhuB,andfhuD),IAA生产(trpABFCDE),生物膜形成(tasA,bsLA,和BSLB),和挥发性化合物生产(AlsD,ilvABCDEHKY,metH,和ispE),和编码水解酶的基因(eglS,amyE,gmuD,ganB,雪橇,和ydhD)。马铃薯盆栽试验表明,Q2H2对马铃薯根系具有明显的促生长作用,对枯萎病的防治效果优于多菌灵。
■这些发现表明,在细菌内生菌中鉴定的菌株特异性基因可能揭示了重要的拮抗和植物生长促进机制。
UNASSIGNED: Endophytes are colonizers of healthy plants and they normally exhibit biocontrol activities, such as reducing the occurrence of plant diseases and promoting plant growth. The endophytic bacterium Bacillus halotolerans Q2H2 (Q2H2) was isolated from the roots of potato plants and was found to have an antagonistic effect on pathogenic fungi.
UNASSIGNED: Q2H2 was identified by morphological observations, physiological and biochemical identification, and 16S rRNA gene sequence analysis. Genes related to the anti-fungal and growth-promoting effects were analyzed using whole-genome sequencing and comparative genomic analysis. Finally, we analyzed the growth-promoting and biocontrol activities of Q2H2 in potato plants using pot experiments.
UNASSIGNED: Antagonism and non-volatile substance plate tests showed that Q2H2 had strong antagonism against Fusarium oxysporum, Fusarium commune, Fusarium graminearum, Fusarium brachygibbosum, Rhizoctonia solani and Stemphylium solani. The plate test showed that Q2H2 had the ability to produce proteases, cellulases, β-1,3-glucanase, dissolved organic phosphate, siderophores, indole-3-acetic acid (IAA), ammonia and fix nitrogen. The suitable growth ranges of Q2H2 under different forms of abiotic stress were pH 5-9, a temperature of 15-30°C, and a salt concentration of 1-5%. Though whole-genome sequencing, we obtained sequencing data of approximately 4.16 MB encompassed 4,102 coding sequences. We predicted 10 secondary metabolite gene clusters related to antagonism and growth promotion, including five known products surfactin, bacillaene, fengycin, bacilysin, bacillibactin, and subtilosin A. Average nucleotide identity and comparative genomic analyses revealed that Q2H2 was Bacillus halotolerans. Through gene function annotation, we analyzed genes related to antagonism and plant growth promotion in the Q2H2 genome. These included genes involved in phosphate metabolism (pstB, pstA, pstC, and pstS), nitrogen fixation (nifS, nifU, salA, and sufU), ammonia production (gudB, rocG, nasD, and nasE), siderophore production (fhuC, fhuG, fhuB, and fhuD), IAA production (trpABFCDE), biofilm formation (tasA, bslA, and bslB), and volatile compound production (alsD, ilvABCDEHKY, metH, and ispE), and genes encoding hydrolases (eglS, amyE, gmuD, ganB, sleL, and ydhD). The potato pot test showed that Q2H2 had an obvious growth-promoting effect on potato roots and better control of Fusarium wilt than carbendazim.
UNASSIGNED: These findings suggest that the strain-specific genes identified in bacterial endophytes may reveal important antagonistic and plant growth-promoting mechanisms.