Abstract:

To utilize endophytic Bacillus amyloliquefaciens YN2014042 (YN42) isolated from tobacco, the colonization and growth promotion of YN42 were studied. We successfully obtained a stable GFP tagged strain YN42-GFP by using natural transformation with pHAPII plasmid introduced into YN42. Inhibition activity showed that the strain YN42-GFP exhibited the comparable ability as the wild type strain YN42 to inhibit13 pathogenic fungi such as Phytophthora parasitica var. nicotianae and Fusarium graminearum. When YN42-GFP was irrigated to tobacco and maize seedlings with 1.00×10 ⁷ CFU/g, its colony number was respectively 1.89 × 10 ⁶ CFU/g, 1.07×10⁴ CFU/g and 0.93×10³ CFU/g of tobacco root, stem and leaf tissues on the 50^th day, and the colony number was 6.67×10³CFU/g of maize leaf on the 25^th day after inoculation, indicating that YN42 could colonize stably in both its indigenous host and non-host plants. When wild type of YN42 was added to tobacco seedling substrate with 1.00×10⁷ CFU/g, the plant type height and fresh weight of aerial parts of 45-day-old tobacco seedling increased by 450.58% and 756.52%, respectively. When maize was drenched with 1.00×10⁷ CFU/g, the plant type height and fresh weight of aerial parts of 30-day-old maize seedling increased by 19.37% and 61.42%, respectively. In conclusion, YN42 not only have a significant inhibitory effect on a variety of plant pathogens but also could colonize well in tobacco and maize, and promote the growth of tobacco and maize. YN42 has a good application prospect in agricultural production.

Key words: tobacco, maize, endophytic bacteria, Bacillus amyloliquefaciens, green fluorescence protein, antagonistic effect, colonization, seedling substrate