Morphological changes of the leaf surfaces of <i>Zea mays</i> induced by rayado fino virus infection

Abstract

Naturally infected field-grown or greenhouse inoculated maize leaves were used to study the anatomical changes caused by rayado fino virus infection. Infected leaves showed the typical symptoms of the disease, characterized by the appearance of small chlorotic spots in the costal regions of the adaxial surface, which may extend to the intercostal zones with increasing severity of the disease. Examination of the chlorotic areas by scanning eIectron microscope reveals abnormal development and reduction in size of stomata and guard cells, or failure of formation of stomata. Reduction in size of the stomatal structures progresses towards the proximal end of the leaf blade and seems to be correlated with intercalary growth. Chlorotic areas appear almost glabrous since macrohairs, typical of the costal areas of healthy leaves, fail to develop. However; microhairs proliferate in other areas covering the veins. Epidermal, siliceous and bulliform cells show abnormal development in severely affected areas.