Abstract: Five purine auxotrophic mutants of Sinorhizobium meliloti strain Rmd 201(WT) were isolated using NTG mutagenesis. Mutants elicited white, small, spherical, determinate, and Fix- pseudonodules on Medicago sativa. These nodules lacked bacteroids and one mutant Rmd 1102(A2) exhibited Exo- phenotype due to production of defective exopolysaccharide, particularly lacking xylose sugar. Cross feeding with xylose as sole carbon source in presence of parental strain restored the wild-type phenotype. Light microscopy revealed aborted infection tubes, bacteroid-devoid cortical cells, and bacterial lysis. Transmission electron microscopy showed that the mutant Rmd 1102 Exo- Pur- formed infection tubes but bacteria lysed within infection tube and could not transform into bacteroids. The mutant also accumulated large sized starch granules, suggesting a defect in starch utilization. Abundant lipid droplets and absence of PHB granules was noted in mutant cells. This pleiotropic mutant exhibited Exo- and Fix- phenotypes, affecting purine biosynthesis and exopolysaccharide production, disrupting normal nodule development and bacteroid production.
Keywords: Sinorhizobium meliloti, NTG mutagenesis, Exopolysaccharide, Purine auxotrophic mutants, Medicago sativa nodules.
Title: TEM STUDIES OF NODULES ELICITED BY SINORHIZOBIUM MELILOTI PLEIOTROPIC MUTANT DEFECTIVE IN EXOPOLYSACCHARIDE SYNTHESIS
Author: Shruti Banswal, Aqbal Singh
International Journal of Life Sciences Research
ISSN 2348-313X (Print), ISSN 2348-3148 (online)
Vol. 12, Issue 2, April 2024 - June 2024
Page No: 46-55
Research Publish Journals
Website: www.researchpublish.com
Published Date: 28-June-2024
