Role of leaf fibro-vascular bundle configuration on feeding of <em>Deltocephalus menoni</em> (Hemiptera: Cicadellidae) in the transmission of White Leaf Disease in sugarcane varieties

Abstract

Purpose: Deltocephalus menoni is the vector of Sugarcane White Leaf Disease (WLD) and the causative agent of White Leaf Disease Phytoplasma (WLDP). WLDP is restricted to the phloem tissues facilitating its dispersal via sap containing phytoplasma during the vector feeding. Here, the configuration of the vascular bundle would be an important characteristic in plant’s resistance to vector feeding and thereby the disease spread. A study was conducted to determine the relationship between feeding of D. menoni and the configuration of leaf fibro-vascular bundles. Research Method: Feeding amount of D. menoni on sugarcane varieties, the configuration of leaf fibro-vascular bundle of leaf blade in gross cross-section and the WLD infection in the natural environment were measured. Variations and correlations between configuration of leaf fibro-vascular bundles between varieties, vector feeding and WLD infection were studied. Major anatomical characteristics of vascular bundles that contribute to feeding were also determined. Findings: The structure of the leaf fibro-vascular bundles varied with the sugarcane variety/ accession and the volume of feeding by D. menoni of sugarcane was correlated with the configuration of the leaf fibro vascular bundle. Distance from the epidermis to vascular parenchyma, distance from epidermis to vascular bundle and thickness of phloem fiber layer were negatively correlated with the feeding amount of D. menoni. The size of phloem tubes, the width of the vascular bundle and the total number of vascular bundles, were positively correlated. The level of WLD infection in natural environment was also correlated with the structure of leaf fibro vascular bundle. Originality/value: Configuration of leaf fibro vascular bundles could be used to predict feeding of D. menoni, level of WLD infection, which could be incorporated into selection and directional breeding of sugarcane against the vector.