BACKGROUND & AIMS:
:Sustainability in crop production has emerged as one of the most important concerns of present era's agricultural systems. Plant growth promoting bacteria (PGPB) has been characterized as a set of microorganisms used for enhancing plant growth and a tool for biological control of phytopathogens. However, the inconsistent performance of these bacteria from laboratory/greenhouse to field level has emerged due to prevailing abiotic stresses in fields. Sugarcane crop encounters a combination of biotic and abiotic stresses during its long developmental stages. Nevertheless, the selection of antagonistic PGPB with abiotic stress tolerance would be beneficial for end-user by the successful establishment of product with required effects under field conditions. Stress tolerant Bacillus xiamenensis strain (PM14) isolated from the sugarcane rhizosphere grown in the fields was examined for various PGP activities, enzyme assays, and antibiotic resistance. Strain was screened for in vitro tolerance against drought, salinity, heat stress, and heavy metal toxicity. Inhibition co-efficient of B. xiamenensis PM14 was also calculated against six phyto-pathogenic fungi, including Colletotrichum falcatum (53.81), Fusarium oxysporum (68.24), Fusarium moniliforme (69.70), Rhizoctonia solani (71.62), Macrophomina phaseolina (67.50), and Pythium splendens (77.58). B. xiamenensis is reported here for the first time as the rhizospheric bacterium which possesses resistance against 12 antibiotics and positive results for all in vitro PGP traits except HCN production. Role of 1-aminocyclopropane-1-carboxylate deaminase in the amelioration of biotic and abiotic stress was also supported by the amplification of acds gene. Moreover, in vitro and in vivo experiments revealed B. xiamenensis as the potential antagonistic PGPR and bio-control agent. Results of greenhouse experiment against sugarcane red rot indicated that inoculation of B. xiamenensis to sugarcane plants could suppress the disease symptoms and enhance plant growth. Augmented production of antioxidative enzymes and proline content may lead to the induced systemic resistance against red rot disease of sugarcane. Thus, the future application of native multi-stress tolerant bacteria as bio-control agents in combination with current heat, drought, salinity, and heavy metal tolerance strategy could contribute towards the global food security.
背景与目标:
: 作物生产的可持续性已成为当今农业系统最重要的问题之一。植物生长促进细菌 (PGPB) 已被表征为用于促进植物生长的一组微生物和植物病原体的生物控制工具。然而,由于田间普遍存在的非生物胁迫,这些细菌从实验室/温室到田间水平的不一致表现已经出现。甘蔗作物在其漫长的发育阶段会遇到生物和非生物胁迫的组合。尽管如此,通过成功建立在现场条件下具有所需效果的产品,选择具有非生物胁迫耐受性的拮抗PGPB对最终用户将是有益的。检查了从田间种植的甘蔗根际分离出的耐胁迫性夏门氏芽孢杆菌 (PM14) 的各种PGP活性,酶测定和抗生素抗性。筛选了菌株对干旱,盐度,热胁迫和重金属毒性的体外耐受性。还计算了夏门芽孢杆菌PM14对六种植物致病性真菌的抑制共效率,包括镰孢炭疽菌 (53.81),尖孢镰刀菌 (68.24),小镰刀菌 (69.70),茄状根瘤菌 (71.62),菜豆 (67.50) 和腐霉 (77.58)。这里首次报道了夏门氏菌作为根际细菌,它对12种抗生素具有抗性,并且对除HCN生产外的所有体外PGP性状均具有阳性结果。acds基因的扩增也支持1-氨基环丙烷-1-羧酸脱氨酶在改善生物和非生物胁迫中的作用。此外,体外和体内实验表明,夏蒙芽孢杆菌是潜在的拮抗PGPR和生物防治剂。针对甘蔗红腐的温室试验结果表明,将夏蒙芽孢杆菌接种到甘蔗植株上可以抑制病害症状,促进植株生长。抗氧化酶和脯氨酸含量的增加可能导致诱导的对甘蔗红腐病的系统抗性。因此,未来将天然耐多胁迫细菌作为生物防治剂,结合当前的热量,干旱,盐度和重金属耐受策略,可以为全球粮食安全做出贡献。