The seed endophytic microbiota of Citrus limon L. Burm. F.

Background Plant seeds possess a complex microbiota which may play a crucial rolein a plethora of mechanisms, such as preservation, germination, seedling development, plant growth and health. In particular, seed endophytic microbiota is gaining more and more consideration due to the fact that it may be vertically transmitted to ensure individual competitive advantages. The Citrusspecies, including C.limon,areone of the most economically important evergreen fruit crops in the world. Objectives i)Identification and characterization ofmicrobial isolates from Citrus limon L. Burm. F. seed endosphere. ii) Structure of Citrus limon L. Burm. F. seed endosphytic microbiota. Methods -Surface-sterilization of Citrus limon L. Burm. F. seeds. - Strain isolation and phylogenetic characterization by 16S rDNA sequence. - Next Generation Sequence Technology analysis (NGS) of metagenomic DNA by pyrosequencing of 16S rDNA. - Fluorescence In Situ Hybridization coupled with Confocal Laser Scanning Microscopy (FISH-CLSM). Conclusions Culture-dependent analysis allowed the isolation of several Staphylococcus spp. and fungi belonging to genera Aspergillus, Quambalaria and Efibula from surface-sterilized seeds. These results weresupported by the detection of bacterial cells and micro–colonies in seed cryosections by FISH-CLSM. In fact, this finding highlighted the presence of Firmicutes and other bacteria colonizing intercellular spaces. NGS-basedcharacterization using metagenomic DNA from surface-sterilized seeds is being carried out in order to elucidatethe microbiota structure. Culture-dependent approaches allowed the isolation of several bacterial strains belonging to the genus Staphylococcus and several fungal strains belonging to the genera Aspergillus, Quambalaria and Efibulafrom seed endosphere. These results were supported by the detection of bacterial cells and micro–colonies in seed cryosections by FISH-CLSM. In particular, this analysis highlighted the presence of Firmicutes and other bacteria colonizing intercellular spaces. NGS-based characterization using metagenomic DNA from surface-sterilized seeds is being carried out in order to elucidate the microbiota structure.