Expression of Xanthomonas oryzae pv.oryzae hrp Genes in XOM2,a Novel Synthetic Medium

概要

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To analyze the regulation of hrp expression and to detect and identify hrp-dependent secretion proteins of plant- pathogenic bacteria, an appropriate hrp-inducing medium is indispensable. In this study, two efficient hrp-inducing media for Xanthomonas oryzae pv. Oryzae were designed by assaying the expression of a hrcU (the first gene of the hrpC operon) and a gus (β-glucuronidase) fusion gene. We modified XVM2, which is a hrp-inducig medium for X. campestris pv. vesicatoria, by adding 0.01% xylose in place of fructose and sucrose (0.18 and 0.34%, respectively) as a sugar source. The resulting medium induced approximately 15-fold more GUS activity from transformants containing a hrcU :: gus gene than did XVM2. Moreover, a methionine-containing synthetic medium with 0.18% xylose as a sugar source was able to induce much stronger expression of HrcU : : GUS, with GUS activity approximately 100-fold greater than that in XVM2. Induction depended on a regulator, HrpXo, and the PIP (plant-inducible-promoter) box, suggesting that HrcU : : GUS was expressed in a hrp-dependent manner. The induction of operons hrp A to hrpF in XOM2 was also confirmed. These results suggest that both media, especially XOM2, are highly efficient hrp-inducing media for X. oryzae pv. Oryzae. (Received October 7, 2002 ; Accepted November 22, 2002)
日本植物病理学会の論文
2002-12-25