The Role of the Extracellular Cellulase Gene in Xanthomonas oryzae pv.oryzae on Bacterial Leaf Blight = 벼흰빛 잎마름병의 유발에 미치는 섬유소 분해효소 유전자의 역할

다국어 초록 (Multilingual Abstract)

A plasmid, designated pXC3-43, encoding an extracellular cellulase activity from Xanthomonas oryzae pv. oryzae(Ishima) was reported previously by authors^1). The cellular distribution of the endoglucanase activities of pXC3-43 and X. o. pv. oryzae was almost exculusively extracellular. Total endoglucanase activity expressed by the pXC3-43 was about 80% of X. o. pv. oryzae k1 wild type. Tn5 mutagenesis of pXC3-43 revealed that extracellular cellulase structural gene is located in a ca. 5 kb KpnI fragment. To examine the role of the extracellular cellulase in disease process, three cellulase-minus mutants of X. o. pv. oryzae were constructed by marker exchange of negative Tn5 insertions into the chromosome of the wild type. These cellulase -minus mutants were as virulent as the wild type in pathogenicity test on leaves of rice(Oryzae sativa L.). Furthermore, When investigated under transmission electron microscopy (TEM), bacterial leaf blight(BLB) symptoms by the cellulase-minus mutants, X. o. pv. oryzae K1::Tn5 were similar to those by wild type. These results suggest that the extracellular cellulase of X. o. pv. oryzae is not primary mechanism of pathogenesis for the pathogenesis of BLB, but mightbe involved in an early disease developmental stage.