Characterization of Burkholderia gladioli strains causal agents of saffron (Crocus sativus L.) bacterial rot

Burkholderia gladioli is the causal agent of a bacterial disease
recently reported in saffron (Crocus sativus L.) grown in central
Sardinia (Italy). The symptoms were rot of emerging flowers and
shoots, and spots on leaves. In the last two years the disease has
been particularly harmful, reducing flowering by some 80%. Isolations
on nutrient glucose agar from symptomatic plants produced
two types of colony. The first type (ten isolates) was round,
wrinkled, and yellowish. The second type (fifteen isolates) was
round, smooth and colourless. In pathogenicity tests, the twenty
five isolates reproduced symptoms on saffron plants, while only
the first type of isolate was pathogenic on gladiolus leaves. The
twenty five isolates were analyzed with the computerised BIOLOG
system, conventional tests and genomic tests such as PCR
and PCR-RFLP. BIOLOG, conventional tests and PCR using
LP1 and LP4 primers, identified all isolates as Burkholderia gladioli.
PCR-RFLP analysis using three restriction enzymes (AluI,
DdeI and BssKI), identified only ten of the isolates (nine wrinkled
and one smooth) as B. gladioli pv. gladioli. Our evidence indicates
that other B. gladioli forms are also involved in this bacterial rot
of saffron, and further studies are under way to verify this.