Studies of the genetic diversity of Macrophomina phaseolina isolates from Argentina using AFLP markers

REZNIKOV, S.; VELLICCE, G.; GONZALEZ, V.; GARCIA, M.G.; ROCHA, C.M.L.; PLOPER, L.D.; CASTAGNARO, A.P.

Durban

Congreso; World Soybean Research Conference IX (WSRC IX); 2013

Protein Research Foundation

Approximately 40 infectious diseases have been reported in soybean in Argentina, causing annual losses of up to 900,000 metric tons and costs of over US$ 250 million (Ploper, 2004; Wrather et al, 2010). Charcoal rot, caused by Macrophomina phaseolina (Tassi) Goid, is one of the most prevalent diseases affecting roots and lower stems in northern Argentina, especially when warm and dry weather conditions prevail during soybean reproductive stages. Severe charcoal rot epidemics occurred in recent years (2000-2001, 2002-2003, 2004-2005, and 2011-2012), causing heavy losses in various provinces and total losses in some fields. In addition to soybean, this soil borne fungus can also infect more than 500 cultivated and wild plant species. The objective of the present study was to evaluate M. phaseolina molecular diversity, gene flow, and genetic structure, which constitutes critical information for soybean breeders. An AFLP (Amplified Fragment Length Polymorphisms) technique was used to assess the genetic diversity of M. phaseolina isolates from different provinces in Argentina (19 from Tucumán, 5 from Santiago del Estero, 3 from Buenos Aires, 3 from Salta, and 1 from Santa Fe), which had been obtained from different hosts (22 from soybean, 3 from dry bean, 2 from chickpea, 1 from lentil, 1 from sunflower, 1 from peanut, and 1 from gerbera). From the 31 M. phaseolina isolates, a total of 662 bands were amplified with 16 pairs of AFLP primers. From the total number of bands, 89.81% were polymorphic. Cluster analysis showed no clear association among geographical origins or hosts and AFLP profiles. Analysis of molecular variance (AMOVA) showed no genetic differentiation of M. phaseolina among provinces; the total variation (100%) was detected within provinces, with a PhiST value of 0.0. AMOVA results, considering host origin, showed no genetic differentiation of isolates among hosts; the total variation (100%) was detected within hosts, with a PhiST value of 0.0. These results indicate that there is not enough isolation to produce genetic differentiation, thus confirming that gene flow occurs among these areas and hosts. References Ploper LD, 2004. Economic importance and control strategies for the major disease in Argentina. In. Proceedings VII World Soybean Research Conference, Foz de Iguazu, PR, Brazil.606-614. Wrather A, Shannon G, Balardin R, Carregal L, Escobar R, Gupta G K, Ma Z, Morel W, Ploper D and Tenuta A, 2010. Effect of diseases on soybean yield in the top eight producing countries in 2006. Online. Plant Health Progress doi:10.1094/PHP-2010-0125-01-RS.