Isolation And Gene Cloning Of Rice Root Hair Short Mutant, Krhs2

As an important component of plant root system,root hair greatly increases the area available for the absorption of water and nutrient.Root hairs differentiate from epidermic cells.Understanding the molecular mechanisms of root hair initiation and development is of important for crop improvement of nutrient uptake efficiency.In addition,the mechanism would provide a valuable model to study of the initiation and apoptosis of unicells.A rice(Oryza sativa L.)mutant with significant shorter root hairs was selected from a EMS mutant library developed from rice cultivar,kasalath.It was named as krhs2(kasalath root hair short mutant 2).No significant difference was observed in phenotypes of shoots,primary,adventitious,and lateral roots between the krhs2 and the wild type(WT).Genetic analysis indicated that the mutation was controlled by a single recessive nuclear gene.Physiological test showed the shortness of root hair in the mutant is insensitive to application of phytohormones,including NAA,ACC and 6-BA.Using map-based cloning,the mutation was mapped to Os03g0300000 loci in chromosome 3.Sequencing of the corresponding gene showed a single nucleotide mutant in krhs2 caused the switch of glycine into argining at the 233rd aa of the protein.Blast search showed that the gene encodes for a xylosyltransferase, designated OsXT1.Studies have showed that xylosyltransferase participates in cell wall synthesis and assemble in plants.It is possible that xylosyltransferase may regulate the growth of root hair by monitoring formation of cell walls.In conclusion,we cloned a rice gene controlling the development of root hair in rice through forward genetic approach.