TABLE 1.

Distribution of XorI and XorII DNA modification systems of X. oryzae pv. oryzae in Asia^a

Region of Asia and country of origin	No. of strains	No. of strains with the following DNA modification system patternb:				Genetic diversityc
		XorI+XorII+	XorI+XorII−	XorI−XorII+	XorI−XorII−
South
India	10	0	0	0	10	0.98
Nepal	33	0	0	6	27	0.92
Southeast
Philippines	64	18	0	33	13	0.97
Malaysia	7	2	1	4	0	0.72
Indonesia	14	4	0	10	0	0.59
Northeast
China	43	2	38	1	2	0.93
Korea	18	4	14	0	0	0.89
Genetic diversity in each DNA modification system groupd		0.95	0.74	0.97	0.95

^aThe distribution of the four different R-M systems was nonrandom within the three geographic regions of Asia (south, southeast, and northeast), based on an analysis by Fisher’s exact test (P = 0.00001). 

^bThe DNA modification system phenotype was determined by sensitivity or resistance to PstI (isoschizomer of XorI) and XorII and/or its isoschizomer PvuI as well as hybridization with xorIIM and xorII-vsr genes in pE7.0. Resistance to digestion indicates that the DNA modification system is present (+), and sensitivity to digestion indicates that the system is absent (−). 

^cGenetic diversity was calculated with the formula [n/(n − 1)][1 − ΣX_i²], where X_i is the proportion of the ith RFLP type within a group and n is the number of strains tested in each group. Data are from RFLP analysis performed with two probes, pJEL101 and pBSavrXa10 (1). Diversity was calculated from the combined data for each country. Data for Japan are not reported because RFLP data were not available for these strains. 

^dGenetic diversity determined with RFLP data as described in footnote c but partitioned for DNA modification system group.