New bacteria genera associated with rice (Oryza sativa L.) in Cuba promote the crop growth

Abstract

Introduction. The rice cultivar INCA LP-7 is one of the eleven principal cultivars in Cuba due to their high yield potential, salinity tolerance, and pathogens resistance. However, there are not reports about the isolation, identification, and characterization of bacteria associated to this cultivar that promote its growth. Objective. To select promising bacteria from the rhizosphere of the INCA LP-7 rice cultivar to promote the crop growth. Materials and methods. The investigation was carried out in 2015 and 2016 at the Instituto Nacional de Ciencias Agropecuarias, Cuba and Instituto de Investigaciones Biologicas Clemente Estable, Uruguay. The 16SrNA gene of bacteria associated with the INCA LP-7 rice cultivar was isolated and identified by sequencing. Characterization was performed as plant growth promoting bacteria and the effect of bacterial inoculation on rice growth was studied. Results. Eleven rizopheric bacteria were isolated from rice plants of the INCA LP-7cultivar. A phylogenetic analysis showed that for the first time in Cuba Pantoea, Acinetobacter, and Mitsuaria genera were reported associated with rice. Rhizobium and Enterobacter genera were also informed as rhizospheric bacteria of INCA LP-7 rice cultivar. Some isolates solubilize inorganic phosphates and potassium, produce siderophores and indolic compound, had exo-celulase and protease activity and formed biofilm. The inoculation of isolates belonging to Pantoea genus produced an increase in height, root length, and biomass of rice plants under greenhouse conditions. Conclusions. Pantoea sp. GG1 and Pantoea sp. GG2 were the most promising strains for the inoculation of the INCA LP-7 rice cultivar. This is the first report in Cuba that focuses on the characterization of the bacterial microbiota part associated to Cuban rice cultivar INCA LP-7 and reports bacteria of the Pantoea genus as crop growth promoters.

Endophytic Seed-Associated Bacteria as Plant Growth Promoters of Cuban Rice (Oryza sativa L.)

“…The bacterial community associated with the rhizosphere of cultivars INCA LP-5 and INCA LP-7 has been previously studied [ 25 , 26 ]. However, this is the first study describing the presence of bacteria in the seeds of both cultivars.…”

“…This fact suggests the possibility of developing and applying universal microbial inoculants to benefit global rice production. A previous study showed that around 64% of culturable strains from the rhizosphere of the rice cultivar INCA LP-7 belonged to the genus Pantoea [ 26 ]. Our result showed the presence of Pantoea as the bacterial endophytes of rice seeds from the cultivar INCA LP-7.…”

“…In Cuba, the PGPB community associated with rice rhizosphere is mainly composed of species belonging to the genera Azospirillum , Herbaspirillum , Bacillus , Burkholderia , Pseudomonas, and Azotobacter [ 22 , 23 , 24 ]. Moreover, bacterial strains belonging to the genera Rhizobium , Enterobacter , Pantoea , Mitsuaria , Acinetobacter , and Pseudomonas were recently reported in the rhizosphere of Cuban rice cultivars INCA LP-5 and INCA LP-7 [ 25 , 26 ]. However, it is unknown how seed endophytic bacteria associated with Cuban rice can enhance plantlet growth.…”