Binds together with S18 to 16S ribosomal RNA (By similarity). Prevents non-specific action of the splicing factor CFM3b during plastid rRNA biogenesis to improve the accuracy of plastid rRNA processing (PubMed:32143506). Required for plastid functions such as photosynthesis, intracellular distribution, plastid rRNAs biosynthesis and plastid gene expression in roots (PubMed:29367414, PubMed:32143506). Involved in a sucrose-conditional process important for the organization of root lateral and apical meristems (e.g. establishment of RAM from pericycle and symplasmic connectivity), and subsequent primary and lateral roots development (PubMed:12581310, Ref.6, PubMed:29367414). Modulates C18 unsaturated fatty acid metabolism (Ref.6). Interacts with CFM3B/SPRT2 in plastids. Present in roots plastids and in leaves chloroplasts. Expressed ubiquitously in roots, leaves, stems, flower buds, flowers and siliques. In underground tissues, observed in root tips and differentiated portions of primary roots, as well as in lateral root primordia. Decreased leaf photosynthetic activity, reduced accumulation of plastid rRNAs (both mature and immature) in roots and altered root plastid gene expression leading to small plants with pale-green leaves (PubMed:29367414, PubMed:32143506). Abnormal intracellular distribution of plastids (PubMed:29367414). Altered fatty acid composition of membrane lipids leading to an increased oleic acid (18:1) level at the expense of alpha-linolenic acid (18:3) level among total fatty acids, especially in root tissues (Ref.6). Aberrant lateral root phenotype that lack stem cells and associated with disrupted stem cell patterning and changes in expression of several root stem cell regulators (Ref.6, PubMed:12581310, PubMed:29367414, PubMed:32143506). Exhibits a sucrose-conditional defect in the patterning of distal elements in the primary and lateral roots meristems (PubMed:12581310, PubMed:29367414). Abnormal symplasmic connectivity between primary root and lateral root primordia (PubMed:29367414). The double mutant rfc3-2 sprt2-1 is rescued for primary and lateral root development as well as for plastid rRNA level compared to the single mutant rfc3-2 (PubMed:32143506). Belongs to the bacterial ribosomal protein bS6 family.