From a collection of 152 pseudomonads isolated from diseased beans in Spain, 138 (91%) of the strains were identified as Pseudomonas syringae pv. phaseolicola and the rest as P. syringae pv. syringae. The P. syringae pv. phaseolicola strains produced typical water-soaked lesions on bean pods, although 95 of them did not produce phaseolotoxin in vitro. Ninety-four of these isolates did not produce the expected 0.5-kb product after polymerase chain reaction (PCR) amplification using primers specific for open reading frame (ORF) 6 of the phaseolotoxin (tox) gene cluster and did not contain DNA homologous to ORF 6 in Southern hybridization experiments. To our knowledge, this is the first report of the widespread occurrence in the field of strains of P. syringae pv. phaseolicola lacking the tox cluster, which contrasts sharply with the general belief that Tox(+) isolates are the only ones with epidemiological importance. Additionally, the tox(-) isolates were not specifically detected by a commercial polyclonal antisera in an enzyme-linked immunosorbent assay. Accordingly, it is possible that the certification of seed lots as free of the pathogen cannot be reliably done in Spain, or in any other country where tox(-) strains might occur frequently, using current PCR or serological protocols. The amplification of three avirulence genes by PCR allowed us to make predictions of the P. syringae pv. phaseolicola race structure, as confirmed by plant assays. Six races (races 1, 2, 5, 6, 7, and 9) were identified, with race 7 being the most prevalent (46.1%) followed by races 6 (21.3%) and 1 (9.0%). All the tox(-) isolates contained gene avrPphF, typical of races 1, 5, 7, and 9.

The antioxidant activity and chemical composition of essential oils and methanolic extracts of twenty Spanish Thymus mastichina L. populations were studied. Both essential oils and methanolic extracts possessed antioxidant properties. However, the total phenol contents of the methanolic extracts varied between 2.90 and 9.15 mg GAE/g extract and the EC 25 values of DPPH free radical scavenging activity between 0.90 and 3.45 mg/mL for the methanolic extracts and 78e241 mg/mL for essential oils, these showing low antioxidant potential. Actually, in essential oils the main compound determined was the 1,8-cineole (56.8e69.6%), whereas thymol, g-terpinene, terpinolene and geraniol (species with considerable DPPH scavenging activity) were observed in low amounts. Concerning methanolic extracts, rosmarinic acid was the most abundant polyphenol (1.70e9.85 mg/g), followed by methoxysalicylic acid, apigenin, kaempferol and luteolin.

Common bacterial blight is a severe disease of common bean (Phaseolus vulgaris L.) worldwide. Use of resistant cultivars is crucial for its control. The objectives were to (i) assess the progress made in breeding large‐seeded Andean bean developed between 1974 and 2010 and (ii) determine their resistance‐linked sequence characterized amplified region (SCAR) marker composition. Ten Andean and four Middle American common bacterial blight resistant beans including checks were evaluated in the greenhouse in 2011. Bacterial strains ARX8AC and Xcp25 were used to inoculate primary and trifoliolate leaves. The mean disease score of the trifoliolate was 5.0 and of the primary leaf was 2.8. Strain Xcp25 had a mean score of 3.8 in primary and 5.9 in trifoliolate leaves. The respective scores for ARX8AC were 1.9 and 4.2. Andean ‘Montcalm’, with the SAP6 quantitative trait loci (QTL) and USDK‐CBB‐15, and USWK‐CBB‐17, with the SAP6 and SU91 QTL, showed an intermediate response to ARX8AC and a susceptible response to Xcp25. Middle American VAX 1 with SAP6, Andeans 08SH‐840 and CXR 1 with SAP6 and SU91, and RCS52‐2, RCS53‐3, and RCS63‐5B with SU91 and BC420 were resistant or intermediate to both strains. Middle American VAX 3 and VAX 6, with SAP6 and SU91, had the highest levels of resistance to ARX8AC, but their responses to Xcp25 were similar to the latter Andean group. Thus, significant improvement has been achieved, but breeding for yet higher levels of resistance, recovery of commercial seed types, and improving yield and other agronomic traits should be emphasized.

Common bacterial blight (CBB) disease of the common bean (Phaseolus vulgaris) is caused by Xanthomonas campestris pv. phaseoli and the brown-pigmented variant X. campestris pv. phaseoli var. fuscans. CBB first was described in Castilla y León County, Spain, in 1940, and is now a major constraint on common bean production. In this secondary center of diversity of the common bean, large-seeded Andean cultivars predominate, although medium-seeded Middle American cultivars also are grown. Xanthomonad-like bacteria associated with CBB in Castilla y León were characterized on the basis of carbohydrate metabolism, brown pigment production, genetic analyses (repetitive-element polymerase chain reaction [rep-PCR] and random amplified polymorphic DNA [RAPD]) and pathogenicity on cultivars representing the two common bean gene pools (Andean and Middle American). X. campestris pv. phaseoli was more prevalent (80%) than X. campestris pv. phaseoli var. fuscans (20%). Patterns of carbohydrate metabolism of Spanish CBB bacteria were similar to those of known strains; and only X. campestris pv. phaseoli var. fuscans strains utilized mannitol as a sole carbon source. rep-PCR and RAPD analyses revealed relatively little genetic diversity among Spanish X. campestris pv. phaseoli strains, and these strains were placed together with New World strains into a large cluster. Similar to other New World strains, representative Spanish X. campestris pv. phaseoli strains were highly pathogenic on bean cultivars of both gene pools, showing no gene pool specialization such as that found in certain East African strains. Genetic analyses and pathogenicity tests confirmed and extended previous results, indicating that these East African strains represent distinct xanthomonads that independently evolved to be pathogenic on common bean. X. campestris pv. phaseoli var. fuscans strains were more closely related and genetically distinct from X. campestris pv. phaseoli strains. However, two distinct clusters of X. campestris pv. phaseoli var. fuscans strains were identified, one having the most New World strains and the other having the most African strains. Spanish strains were placed in both clusters, but all strains tested were highly pathogenic on bean cultivars of both gene pools. Together, our results are consistent with multiple introductions of CBB bacteria into Spain. These findings are discussed in terms of breeding for CBB resistance and the overall understanding of the genetic diversity and evolution of CBB bacteria.

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