Abstract
Bacterial microorganisms which are latent in in vitro cultures can limit the efficiency of in vitro methods for the conservation of genetic resources. In this study we screened 2,373 accessions from the in vitro sweetpotato germplasm collection of the International Potato Center in Lima, Peru for bacteria associated with plantlets in tissue culture through a combination of morphological methods and partial 16S rDNA sequencing. Bacteria were detected in 240 accessions (10% of the accessions screened) and we were able to isolate 184 different bacterial isolates from 177 different accessions. These corresponded to at least nineteen Operational Taxonomic Units (OTUs) of bacteria, belonging to the genera Sphingomonas, Bacillus, Paenibacillus, Methylobacterium, Brevibacterium, Acinetobacter, Microbacterium, Streptomyces, Staphylococcus, and Janibacter. Specific primers were developed for PCR based diagnostic tests that were able to rapidly detect these bacteria directly from tissue culture plants, without the need of microbial sub-culturing. Based on PCR screening the largest bacterial OTUs corresponded to a Paenibacillus sp. closely related to Paenibacillus taichungensis (41.67%), and Bacillus sp. closely related to Bacillus cereus (22.22%), and Bacillus pumilus (16.67%). Since in vitro plant genetic resources must be microbe-free for international distribution and use, any microbial presence is considered a contamination and therefore it is critical to clean all cultures of these latent-appearing bacteria. To accomplish this, plantlets from in vitro were transferred to soil, watered with Dimanin® (2 ml/l) weekly and then reintroduced into in vitro. Of the 191 accessions processed for bacterial elimination, 100% tested bacteria-free after treatment. It is suspected that these bacteria may be endosymbionts and some may be beneficial for the plants.
Highlights
Sweetpotato [Ipomoea batatas (L.) Lam] is the sixth most important crop for global food security (CIP, 2020)
Each tube was incubated at room temperature (RT) for 3 days; if bacterial growth was not apparent, the tubes were incubated at 28◦C for 3 additional days followed by 3 weeks at RT
Through morphological characterization and partial 16S Ribosomal DNA (rDNA) sequencing, we were able to detect at least 19 Operational Taxonomic Units (OTUs) of bacteria isolated from the in vitro cultures of sweetpotato (Tables 1, 2)
Summary
Sweetpotato [Ipomoea batatas (L.) Lam] is the sixth most important crop for global food security (CIP, 2020). It is a perennial vine, it is usually grown as an annual crop. One of the current forms of ex situ conservation of clonal germplasm is by in vitro tissue culture. In vitro conservation offers advantages such as: lack of field infections, protection against adverse environmental conditions; timely access to material, as well as the feasibility of maintaining disease-free material for propagation and export. Tissue culture allows rapid clonal propagation of a large number of plants in a short time and in small spaces (Benson, 2002)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
