Multiplication and Distribution of Sugarcane White Leaf Phytoplasma Transmitted by the Leafhopper, Matsumuratettix hiroglyphicus (Matsumura) (Hemiptera: Cicadellidae), in Infected Sugarcane

Abstract

White leaf is one of the most destructive sugarcane diseases, threatening the sugarcane industry in the Asian region. A better understanding of the distribution and accumulation of sugarcane white leaf (SCWL) phytoplasma in the various parts of the host plants is important for selecting the most suitable sugarcane tissue for disease-free seed propagation materials and for proper disease detection. In this study, the multiplication and distribution of phytoplasma in 3-month-old sugarcane plants inoculated with SCWL phytoplasma in a specific area using the leafhopper vector, Matsumuratettix hiroglyphicus (Matsumura), were analyzed. Quantitative PCR was used to detect and quantify the SCWL phytoplasma that spread within the plant from the inoculated leaf to the main stem, top leaf, and root at 7 days post-inoculation (dpi). It then spread to the other leaves from the bottom to the top (14–28 dpi). The SCWL phytoplasma was detected throughout the plant by 35 dpi. The population of phytoplasma in the inoculated leaves, mainstem, and roots increased by approximately by 1–2-fold each week. At 6 and 9 months post-infection, the accumulation of phytoplasma was highest in the middle of the main stem, low in the new shoot and top internode, and moderate in the bottom internode. Therefore, the middle of the main stem is the preferred part from which tissue should be sampled for detection of SCWL in the mature plants.