Phytoplasma Associated with Symptoms of ‘Tristeza del ajo’(Garlic Decline) in Garlic (Allium sativum L.)

Garlic plants (AlliulII sOliDUIII L. ) showing symptoms of decline. absence of cloves. leaf yellowi ng (in . Rosado Paraguayoʹ and ʹColoradoʹ type) and reddening (i n ʹ Blallcoʹ type). have been observed in certain areas around the city of Cordoba, Argentina. This syndrome was termed ʹIrisleza del ajoʹ (garlic decline) by growers. Symptoms appea r during the second half of the growth cycle. Affected plants die, and ha ve spo ngy bulbs with undeveloped cloves. When symptoms appear close to harvest time, plants show only a colour change in leaves. but bu lbs appear normal. Plants with symptoms showed abunda nt phytoplasma cells when observed under electron microscopy. and strongly reacted with an antiserum raised against the phytoplasl11a associated with ʹChinatree (Melia azedaracil L) declineʹ. Using universal primers to phytoplasma. a DNA fragment from leaf and clove extracts of plants expressing symptoms was amplified by PCR. The PCR amplified product was digested with the restriction enzyme Alu 1, and the generated restriction pattern was ana lysed in polyacrylamide gels. This a llowed the location of the pathogen within Group II I of the classifica tion proposed by Ah rens and Seel1l 0ller ( 1992). These results confirm the association between the symptomatology described as ʹIriSle=a del ajoʹ and a phytoplasma, supporting our first report frol11 1992, on the presence of this prokaryote in garl ic.