Isolation and Characterization of Endophytic Colonizing Bacteria from Agronomic Crops and Prairie Plants

Endophytic bacteria reside within plant hosts without causing disease symptoms. In this study, 853 endophytic strains were isolated from aerial tissues of four agronomic crop species and 27 prairie plant species. We determined several phenotypic properties and found approximately equal numbers of gram-negative and gram-positive isolates. In a greenhouse study, 28 of 86 prairie plant endophytes were found to colonize their original hosts at 42 days postinoculation at levels of 3.5 to 7.7 log(10) CFU/g (fresh weight). More comprehensive colonization studies were conducted with 373 corn and sorghum endophytes. In growth room studies, none of the isolates displayed pathogenicity, and 69 of the strains were recovered from corn or sorghum seedlings at levels of 8.3 log(10) CFU/plant or higher. Host range greenhouse studies demonstrated that 26 of 29 endophytes were recoverable from at least one host other than corn and sorghum at levels of up to 5.8 log(10) CFU/g (fresh weight). Long-range dent corn greenhouse studies and field trials with 17 wild-type strains and 14 antibiotic-resistant mutants demonstrated bacterial persistence at significant average colonization levels ranging between 3.4 and 6.1 log(10) CFU/g (fresh weight) up to 78 days postinoculation. Three prairie and three agronomic endophytes exhibiting the most promising levels of colonization and an ability to persist were identified as Cellulomonas, Clavibacter, Curtobacterium, and Microbacterium isolates by 16S rRNA gene sequence, fatty acid, and carbon source utilization analyses. This study defines for the first time the endophytic nature of Microbacterium testaceum. These microorganisms may be useful for biocontrol and other applications

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Not AvailableConservation agriculture (CA) is a key climate resilient and resource saving technology for higher productivity while reversing soil degradation in rainfed regions. In India, CA in the rice -wheat system of the Indo-Gangetic Plains (IGP) of south Asia has been extensively studied. However, relatively less attention was given to develop strategies to overcome the constraints in the adoption of CA in rainfed regions. Therefore, studies were initiated in rainfed regions under different cropping systems and soil types to standardize the best management practices and to address various constraints related to adoption of CA. Based on the results of experiments conducted in various agro ecosystems it has been found that the effect of CA on crop productivity and soil properties in different experiments are variable, depending on the management factors and duration of the study. Adoption of CA resulted in improvement in crop yield to the extent of 9-36.7% under different cropping systems, increase in net monetary returns by 1487% and rain water productivity by 4-25%. The water infiltration rate was increased by 53.2 -56.8 %, soil organic carbon content increased by 5-45.1% under different cropping systems at different soil depths. The available soil moisture content increased by 1.8-46.8% and the available soil nitrogen, phosphorus and potassium increased by 2.7-41.6,0.6-64.8 and 6.1-26.2%, respectively. The energy input under CA decreased by 0.9-57.6%, energy saving increased by 0.9- 34.88% and the energy use efficiency increased by 9.47-66.8%. The runoff and soil loss also decreased by 17.6-37.9% and 44.756.5%, respectively under CA as compared to conventional tillage (CT). Furthermore, we have observed that CA integrated with complementary practices like in situ moisture conservation (through permanent conservation furrow or permanent raised bed and furrow) in maize/horse gram-pigeonpea, maizepigeonpea system, weed and nutrient management practices in maize-pigeonpea, pearl millet-pigeonpea and cotton-pigeonpea improved the crop productivity and soil health in rainfed agro-ecosystems. Increase in crop residue retention either through manipulation of harvest height to 30-60 cm in cereals and live mulch with dhaincha in pigeonpea-castor system, improve soil health, resilience to climate change, productivity and profitability. These technologies have feasibility of adoption by the farmers.Not Availabl