Xanthomonas campestris pv. campestris (Xcc) causes the black rot of cruciferous plants. This seed-borne bacterium is considered as the most destructive disease to cruciferous crops. Although sources of contamination are various, seeds are the main source of transmission. Typical symptoms of black rot were first observed in 2011 on cabbage and cauliflower fields in the main production areas of Algeria. Leaf samples displaying typical symptoms were collected during 2011 to 2014, and 170 strains were isolated from 45 commercial fields. Xcc isolates were very homogeneous in morphological, physiological and biochemical characteristics similar to reference strains, and gave positive pathogenicity and molecular test results (multiplex PCR with specific primers). This is the first record of Xcc in Algeria. Genetic diversity within the isolates was assessed in comparison with strains isolated elsewhere. A multilocus sequence analysis based on two housekeeping genes (gyrB and rpoD) was carried out on 77 strains representative isolates. The isolates grouped into 20 haplotypes defined with 68 polymorphic sites. The phylogenetic tree obtained showed that Xcc is in two groups, and all Algerian strains clustered in group 1 in three subgroups. No relationships were detected between haplotypes and the origins of the seed lots, the varieties of host cabbage, the years of isolation and agroclimatic regions.

The present study was carried out to ascertain the genetic status of soybean and maize crops introduced in Algeria and to test local and imported products containing maize and soybean for the presence of genetically modified organisms (GMO into the food and feed chain). Samples from crops and processed food products were selected, randomly sampled and screened by polymerase chain reaction (PCR) for the presence of the 35S cauliflower mosaic virus promoter (P35S CaMV) and the Agrobacterium tumefaciens nopaline synthase (nos) terminator, commonly found in transgene cassettes. Results showed that GMOs were absent in all crop samples, but present in 29 food and feed samples. These analyses are discussed for the efficiency of the Algerian regulation and the absence of labelling and traceability mechanisms within the country.

Xanthomonas campestris pv. campestris is a seed-borne bacterium that causes black rot on Brassicaceae. Ensuring seed lot sanitary quality is the most efficient control strategy against bacterial diseases. Currently, the procedures adopted in the control of seed lots are mainly based on microbiological techniques combined with PCR or plant inoculation which is time and money consuming. The aim of this study was to propose a reliable and rapid detection technique of living X. c. pv. campestris in cabbage seeds. We have shown that not all cells of X. campestris is able to grown on rich medium after washing and soaking seeds as no colony of X. campestris was detected on inoculated seeds, whereas plantlets develop symptoms 7-14 days after germination. The PCR technique used alone does not address the viability of bacteria in samples. We set up a technique named seed-qPCR for the detection of living X. c. pv. campestris bacterial cells in seed lots. This technique is based on an enrichment of bacterial population associated with infected seeds by seed germination coupled with real-time Taq-man PCR after extraction of the target DNA. It is an inexpensive technique that allow the detection of down to 1 contaminated seed among 10 000 healthy seeds. The seed-qPCR method combines an efficient extraction based on bacterial multiplication on seedlings with a sensitive technique qPCR for the detection of bacteria in seed lots.