Two genotypes of Xanthomonas oryzae pv. oryzae virulence identified in West Africa

Abstract

Bacterial leaf blight (BLB) caused by Xanthomonas oryzae pv. oryzae (Xoo), is a very destructive rice disease worldwide. The aim of the present study was to examine if the Xoo virulence pathotypes obtained using phenotypic pathotyping could be confirmed using molecular approach. After screening of 60 Operon primers with genomic DNA of two Xoo isolates (virulent pathotype, Vr and mildly virulent pathotype, MVr), 12 Operon primers that gave reproducible and useful genetic information were selected and used to analyze 50 Xoo isolates from 7 West African countries. Genetic analysis revealed two major Xoo virulence molecular type (Mt) which were Mta and Mtb with Mta having two subgroups (Mta1 and Mta2). Mta1 (Vr1) subgroup genotype has occurrence in six countries and Mta2 (Vr2) in three countries while Mtb genotype characterized mildly virulence (MVr) Xoo isolates present in five countries. The study revealed possible linkage and correlation between phenotypic pathotyping and molecular typing of Xoo virulence. Durable resistance rice cultivars would need to overcome both Mta and Mtb Xoo virulence genotypes in order to survive after their deployment into different rice ecologies in West Africa.

Genome editing of an African elite rice variety confers resistance against endemic and emerging Xanthomonas oryzae pv. oryzae strains

“…While information on the spread and severity of BB in Africa is scarce, BB is not yet considered a major threat in Africa; nevertheless, BB is an established disease. The situation is unstable, because climate change affects disease spread, and damage is expected to become more severe in the future due to climate change ( Amos, 2013 ; Laha et al, 2016 ; Sere and Ouedraogo, 2005 ; Verdier et al, 2012b ). Increased demand and the need to improve food security make it essential to generate broad-spectrum and durable resistance in local varieties specifically for Africa.…”

Genome editing of an African elite rice variety confers resistance against endemic and emergingXanthomonas oryzaepv.oryzaestrains

“…While the information on the spread and severity of BB in Africa is scarce, BB is not yet considered a major threat in Africa, but has established. However, climate change affects disease spread, leading to projections that the damage will become more severe in the future (Amos, 2013; Séré et al, 2005; Verdier et al, 2012b). Other factors, such as population growth and increasing yield losses due to pathogens, as well as the distinct Xoo populations in Africa, make it essential to generate broad-spectrum and durable resistance in local varieties specifically for Africa.…”