A TRANSCRIPTOMIC APPROACH TO UNDERSTAND INDUCED RESISTANCE TO BACTERIAL CANKER OF STONE FRUITS ELICITED THROUGH TREATMENTS WITH COPPER GLUCOHUMATES.

Bacterial canker of stone fruits, caused by Xanthomonas arboricola
pv. pruni, is a recurrent disease in Italian peach and plum orchards.
Several field and glasshouse trials on peach and plum were
done, with the aim to effectively control the disease by using some
novel molecules, such as glucohumates. The most remarkable results
were obtained with copper glucohumates (with a reduction
of the disease by ca. 80%). Results are very promising and suggest
the possibility to implement effective control strategies, where
copper compounds and novel molecules are both used in commercial
orchards. In order to study and understand the effect of
the biomolecules used, untreated and glucohumate-treated peach
plants were subject to further molecular analyses in order identify possible genes/sequences involved in the induction of disease resistance.
A transcriptomic approach was developed for detecting
the transcripts present in plant tissues, after elicitation of an induced
protection state. Total RNA was extracted, retro-transcribed
and c-DNA-AFLP was done to identify different sequence
fingerprints in the protected plant tissue. Discrimination of newly
expressed sequences was performed with DHPLC, and comparison
of transcripts was done on the complete peach genome database
in order to identify the genes or sequences involved in the
elicitation of induced resistance. Preliminary data showed, in
treated plants, the presence of nine putative genes like a putative
senescence protein, already described as being involved in the induced
resistance to fire blight in other Rosaceae. Thus, copper
glucohumates might be considered possible candidates for the
elicitation of resistance to bacterial diseases.