During the second half of August 2009 in corn fields located in Northern Italy scattered plants showing reddening symptoms were observed, mainly located at the edge of the fields. Symptoms were clearly visible on the main leaf midribs, and/or on the stalks, and eventually affect the whole plant. Symptomatic plants had smaller size than healthy ones, and corn cobs were sometime malformed and of very little size. In some of the symptomatic plants the cobs produced were of regular size and contains poor shrivelled grains as reported for reddening disease of corn in Serbia (Duduk & Bertaccini, Plant Disease, 90, 1313-1319. 2006). Ten samples of symptomatic, and 4 of asymptomatic corn plants were collected in two different locations and nested PCR assays were carried out on total nucleic acids from 1 g of main leaf midrib and phloem stalk tissues chloroform/phenol extracted. Direct PCR assays with phytoplasma universal primer pair P1/P7 followed by nested PCR with 16S758F/16S1242R (Gibb et al., Phytopathology, 85, 169-174. 1995) primers allowed amplification of 500 bp amplicons from all samples from symptomatic plants, no bands were obtained from asymptomatic samples. Identification of detected phytoplasmas done using RFLP analyses with TruI, Tsp509I and MboII restriction enzymes allow preliminary identification of phytoplasmas belonging to 16SrI (aster yellows), 16SrIII (X disease) and 16SrXII (stolbur) groups, in same cases in mixed infection. Further molecular characterization of these phytoplasmas is in progress together with epidemiological studies to verify the presence of phytoplasma sources, and of possible insect vectors in the two environments. Presence of stolbur phytoplasmas in corn samples with reddening symptoms is confirming the finding in Serbia (Duduk & Bertaccini, above), however this is the first report in Europe of 16SrI group phytoplasmas, and the first report of 16SrIII in corn. The diverse phytoplasmas are associated with indistinguishable symptoms in plants as already worldwide reported in this and in other plant species for phytoplasma infection.
Calari A., N. Contaldo, S. Ardizzi, A. Bertaccini (2010). Phytoplasma detection in corn with reddening in Italy. SITGES : sine nomine.
Phytoplasma detection in corn with reddening in Italy
CALARI, ALBERTO;CONTALDO, NICOLETTA;ARDIZZI, STEFANO;BERTACCINI, ASSUNTA
2010
Abstract
During the second half of August 2009 in corn fields located in Northern Italy scattered plants showing reddening symptoms were observed, mainly located at the edge of the fields. Symptoms were clearly visible on the main leaf midribs, and/or on the stalks, and eventually affect the whole plant. Symptomatic plants had smaller size than healthy ones, and corn cobs were sometime malformed and of very little size. In some of the symptomatic plants the cobs produced were of regular size and contains poor shrivelled grains as reported for reddening disease of corn in Serbia (Duduk & Bertaccini, Plant Disease, 90, 1313-1319. 2006). Ten samples of symptomatic, and 4 of asymptomatic corn plants were collected in two different locations and nested PCR assays were carried out on total nucleic acids from 1 g of main leaf midrib and phloem stalk tissues chloroform/phenol extracted. Direct PCR assays with phytoplasma universal primer pair P1/P7 followed by nested PCR with 16S758F/16S1242R (Gibb et al., Phytopathology, 85, 169-174. 1995) primers allowed amplification of 500 bp amplicons from all samples from symptomatic plants, no bands were obtained from asymptomatic samples. Identification of detected phytoplasmas done using RFLP analyses with TruI, Tsp509I and MboII restriction enzymes allow preliminary identification of phytoplasmas belonging to 16SrI (aster yellows), 16SrIII (X disease) and 16SrXII (stolbur) groups, in same cases in mixed infection. Further molecular characterization of these phytoplasmas is in progress together with epidemiological studies to verify the presence of phytoplasma sources, and of possible insect vectors in the two environments. Presence of stolbur phytoplasmas in corn samples with reddening symptoms is confirming the finding in Serbia (Duduk & Bertaccini, above), however this is the first report in Europe of 16SrI group phytoplasmas, and the first report of 16SrIII in corn. The diverse phytoplasmas are associated with indistinguishable symptoms in plants as already worldwide reported in this and in other plant species for phytoplasma infection.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
