Growth Promotion of Rapeseed (Brassica napus L.) and Blackleg Disease (Leptosphaeria maculans) Suppression Mediated by Endophytic Bacteria

Abstract

Rapeseed is an important oil crop strongly dependent on high agrochemical inputs. Some pathogens, including Leptosphaeria maculans, cause blackleg disease and can drastically decrease yields. Microbial inoculants seem to be a promising solution to these problems. However, a selection of potent bacterial strains able to improve growth and/or suppress disease is needed. Endophytic bacteria (n = 38) isolated from rapeseed plants with exceptionally good growth were screened for plant growth promoting (PGP) traits and L. maculans antifungal activity. A majority of isolates (35) showed the ability to produce siderophores, 17 isolates solubilized phosphate, and 28 isolates inhibited the growth of L. maculans. The six most promising isolates belonging to Bacillus genera were characterized in detail and compared to two previously published PGP strains. Plant growth measured as total weight and root length of rapeseed seedlings was stimulated by all isolates in comparison to control. The best isolate, 1L6, preliminary identified as Bacillus pumilus showed the highest phosphate solubilization, IAA and HCN production, and growth promotion of plants. Isolates with high antifungal activity in screening showed good potential to suppress disease on plants, with 87% reduction of lesions caused by L. maculans. These strains are good candidates to be explored under field use either solely or in combination.

Changes of Endophytic Bacterial Community in Mature Leaves of Prunus laurocerasus L. during the Seasonal Transition from Winter Dormancy to Vegetative Growth

“…Plant, animal, and human pathogenic bacteria may also survive asymptomatically within plant tissues [ 15 ]. Exploration of the diversity and community composition of endophytic bacteria has been traditionally conducted, applying culture-dependent microbiological approaches with a special emphasis on the root plant growth-promoting bacteria of cultivated plants including rapeseed [ 16 ], potato [ 17 ], and sugarcane [ 18 ] because of their large contribution to plant nutrient intake as well as to the high diversity of soil bacteria. While culturing methods are able to uncover specific roles of bacteria, it has been estimated that only 1% of bacterial communities are culturable [ 19 , 20 ].…”

Dynamics, phylogeny and phyto-stimulating potential of chitinase synthesizing bacterial root endosymbiosiome of North Western Himalayan Brassica rapa L.

“…Dey and Raghuwanshi 46 also observed the solubilization index as high as 3.714, and solubilization of tricalcium phosphate was caused by all the isolated endophytic bacterial strains except the one strain RR11. Phosphate solubilization has been observed in various endophytic bacteria strains in a similar range 47 , 48 .…”

Bacterial Strategies for Improving the Yield, Quality, and Adaptability of Oil Crops

“…Bacillus pumilus 1L6 has the highest phosphate solubilization capacity, as well as IAA and HCN production. Moreover, 1L6 significantly decreased the leaf area damaged by L. maculans [106]. Two endophytic strains Pseudomonas protegens Sneb1997 and Serratia plymuthica Sneb2001 have a high biological efficacy for controlling root-knot nematode disease [133].…”