Resumo

GARCIA-JUAREZ, H. Salomón et al. Presence of Xanthomonas albilineans (Ashby) Dowson in sugarcane crops in La Chontalpa, Tabasco, México. Rev. fitotec. mex [online]. 2015, vol.38, n.4, pp.397-404. ISSN 0187-7380.

One of the aggressive diseases of sugarcane is leaf scald caused by Xanthomonas albilineans (Xa). Despite some studies, the State of Tabasco is not known to be affected by Xa. Therefore, the objective of this work was to search for Xa in Tabasco, México, and its distribution. We selected a sugarcane production zone located in La Chontalpa region and carried out a direct sampling in five sugarcane clones (MEX 69-290, MEX 79-431, MEX 68-P-23, CP 72-2086 and RD 75-11), four soil types (Cambisol, Vertisol, Gleysol and Fluvisol) and two rainfall regimes (1793-1936 mm and 1937-2085 mm). A total of 105 sites were selected and located. Samples of 10 stalks were randomly selected in each plantation. Juice extracted from stalk pieces was impregnated on a nitrocellulose membrane, and then revealed by the "Dot blot immunoassay" method. Results showed the presence of Xa in the stems of three asymptomatic clones (MEX 69-290, MEX 68-P-23 y MEX 79-431) with incidences ≥ 10 % in four sampling sites. The distribution of the disease was of the aggregated type, and currently located only at the southern part of the sugarcane production zone. The disease is now in a symptomatic latent period in the positive clones considered tolerant, which lack visual symptoms in the sampling sites. The Xa isolated from two susceptible sugarcane clones (EMEX00-21 and CXZ7564) showed the "pencil lines" symptom in leaves. The molecular analysis performed by amplifying a segment of the 16S rDNA (1392 bp). Maximal similarities were found when compared to sequences of Xa registered in the GenBank. This study is the first report of the presence of Xa in Tabasco, México, confirmed at molecular level.

Palavras-chave : Xanthomonas albilineans; leaf scald; sugarcane.