Georgofili World

Newsletter of the Georgofili Academy

Xylella: a modern italian tale

Once upon a time  there was an enchanted corner of southern Italy, the Salento peninsula, which lived  happily and  was proud of the sea of majestic olive trees that embellished its landscape.  On a bad day,  this blessed spot woke up  with  what looked like a minor problem, i.e. a group of declining plants in an olive grove next to Gallipoli,  a small town on the Ionian coast of the province of Lecce. The “minor problem” soon turned into a major nightmare,  as the decline  began spreading like fire  over an ever increasing  acreage. The cry of pain of the growers who saw their  orchards withering and desiccating did not escape the attention of a group of  knights (i.e. plant pathologists of the University of Bari and of  an outfit of the Italian Research Council) whose daily good deed and committment is the safeguard of  plant health. These knights, promptly wore the  shining armours, jumped on their fiery steeds,  and  rushed  to the aid of the desperate villagers.  In  a short lapse of time the gallant knights,  working like dogs in the field and laboratory,   identified Xylella fastidiosa -a nasty little bacterium and  an American “cadeau”-,  as the one of the major  if not the only cause of the decline.  Highly dependable dectection protocols were developed, the bacterium was isolated in pure culture, its taxonomic allocation (a peculiar divergent strain of X. fastidiosa subsp. pauca)  was determined and confirmed upon sequencing of the whole genome (a DNA molecule 2,514,616 base pair in size), its site of origin (Costa Rica) was hypothesized based on molecular evidence,  a spittlebug (Philaenus spumarius) was identified as the major vector, several infected alternative hosts (trees and shrubs) were found, and pathogenicity tests were initiated. In other words, the basic information for further studies aimed at restraining the disease and, possibly, controlling it was secured. For a moment or two, the knights engaged in these studies had thought that their silent but intensive endeavour could deserve a sign of  appreciation. Wrong! Much to their  unpleasant surprise and dismay, the poor knights in their no longer shining armour  realized that a caravanserai had woken up with its court of  charlatans, jesters, storytellers, miracolous ointment peddlers, sorceressess, and scribblers.  A vociferous set of the most  variegated  kind of associations, all of them  largely deprived of phytopathological knowledge, gave vent to their frustations and challenged  the knights’ work.  Among these, just to quote an example or two, Peacelinks and  ISDE (International Society of Doctors for the Environment), two private voluntary associations (PVA) that pompously call themselves “non governmental organizations” (NGO). However, the most virulent attacks came from those “cliques” whose members ooze ignorance from each single pore. A enlighting example? A group of self-appointed “environmentalists” from the province of  Lecce  possessing  no trace of  scientific knowledge, and not only,  filed an appeal with the Court of Justice of Lecce based on the following theorem: (i) Xylella fastidiosa was introduced in Apulia in 2010 by the Mediterranean Agronomic Institute of Bari (IAMB), the Italian branch of the Centre International de Hautes Etudes Agronomiques of Paris, in the occasion of an international course on  quarantine pathogens. The bacterium escaped from  IAMB’s laboratories and landed in  Gallipoli (some 200 km south of Bari); (ii) the immaculate knights knew of the escape but kept silent waiting  for the outbreak to explode catastrophically. Only then they  made  public the discovery of the disease agent,  to be praised for it.  It goes without saying that  the plaintiffs failed to explain how the bacterium had made such a prodigiously long jump and  how come that, during the journey from Bari to Gallipoli, it had mutated from X. fastidiosa subsp. fastidiosa (the introduced strain) into X. fastidiosa subsp. pauca (the olive-infecting strain).  Any sensibile person, knights included, would have expected that such an airy claim would have been taken with a grain of salt, and rejected by the Court of Justice. Wrong again! The public prosecutor of  Lecce gave credit to the plaintiffs and  decided to proceed with a judicial enquiry based on  article No. 500 of the Italian penal code which is entitled: “Dissemination of a plant or animal disease”. A majestic  monument to incongruity was then erected:  those   who have identified the main cause of olive decline, have characterized  the major pathogen involved in its aetiology and its way of spreading, and are desperately trying to find a way to fight it are suspected to be the main responsible for its dissemination. Since then, the poor knigths, now wearing a definitely matted armour, are the target of  the  caring “attentions” of the prosecutor. Several of them  underwent interrogation, a number of documents were abducted and, finally,  some 16 personal computers or hard disks  were seized and their files copied. For a week or so teaching and research activities were hampered. Anyone could witness that  the wretched knights, now no longer wearing an  armour but just a coat-of-mail,  are gasping for air  in a venomous atmosphere of witch hunting. What worries us, the knights,  and should also worry the  scientific community is the  veritable frontal attack to science and research. This scenario recalls very much the one depicted  by A. Manzoni, an Italian writer of the 19th Century,  in his book “La colonna infame”, where he describes what happened to the people  accused to be  plague spreaders during the Milano’s outbreak of 1630.  These unfortunate individuals were first tortured, then killed. Will the knights (at this point totally naked) undergo the same destiny?

Giovanni P.  Martelli – Università di Bari -