Histological characterization of the sugarcane response to Puccinia kuehnii infection

Abstract

Sugarcane orange rust, caused by Puccinia kuehnii (W. Krüger) EJ Butler, is one of the major diseases impacting sugarcane (Saccharum spp.) production worldwide. The objective of this work was to characterize by histology the development of P. kuehnii in leaves and the response of the cultivars to the disease. Four cultures with different degrees of infection response were inoculated in greenhouse. Microscopy studies were performed in leaf fragments of plants at 5 and 15 days after inoculation. It was shown that the development of fungus structures, prior to foliar tissue penetration, are similar in all cultivars regardless of the type of plant response. It was found that cultivar with grade 1 developed response similar to the hypersensitive response, while grade 2 suggests resistance based on the quantitative contribution of several genes. The results are a contribution towards understanding the genetic basis of orange rust resistance in sugarcane.