AMG-2: SPONTANEOUS MUTATIONS IN <I>XANTHOMONAS CAMPESTRIS</I> PV. <I>CAMPESTRIS</I> AVRBS3 AND AVRBS2 HOMOLOGS ALTER AVIRULENCE ON BRASSICAS WITH RACE-SPECIFIC RESISTANCE.

AMG-2   Agricultural Microbes Genome 2 Conference

Town & Country Hotel, San Diego, CA, January 17-19, 2001.

Poster: Microbial Diversity
P02_01.html

SPONTANEOUS MUTATIONS IN XANTHOMONAS CAMPESTRIS PV. CAMPESTRIS AVRBS3 AND AVRBS2 HOMOLOGS ALTER AVIRULENCE ON BRASSICAS WITH RACE-SPECIFIC RESISTANCE.

ALEXANDER IGNATOV1, Fevzi Djalilov2, Gregori Monakhos2, Galina Pozmogova1,

1 Address:
2 Moscow Agricultural Academy, Timiryazeva Str., 37, Moscow.

In race-specific resistance, single plant resistance genes govern recognition of pathogens carrying particular avirulence genes. Function of putative bacterial avirulence (avr) genes from the brassicas pathogen Xanthomonas campestris pv campestris is recognised by several resistant genotypes of Brassica spp. in what has been shown to be a gene-for-gene manner. The activities of putative avrRb and avrXca4 genes recognised by dominant resistance gene Rb in B genome and dominant resistance gene Xca4 in A genome of brassicas were lost after spontaneous mutations in planta. We found that the avr genes possess structural similarity to avrBs3 and to avrBs2 gene families, present in many Xanthomonas species representing a diverse host range. Thus, the brassicas disease resistance loci conditioning resistance to X. campestris pv campestris can recognize bacterial strains carrying avirulence genes homologous to avr genes typical of other Xanthomonas species.

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