Lasiodiplodia species isolated from Theobroma cacao in the Philippines and their pathogenicity

Abstract

Theobroma cacao is primarily cultivated for its seeds. In the Philippines, where cacao yields are decreased by pod rots and vascular streak dieback (VSD)-like symptoms, the fungus Lasiodiplodia theobromae (Botryospaheriaceae) is the only reported species of Lasiodiplodia reported to cause disease in cacao. Here to identify and determine the pathogenicity of Lasiodiplodia isolates from cacao trees, we isolated Lasiodiplodia from from a leaf with blight (isolate PH22-080), stem with vascular streak (PH22-060), pod rot (PH22-120), an asymptomatic stem (PH22-014), and leaf litter (PH22-007). All strains were pathogenic on wounded leaves and stems and infected pods even without wounds. On the basis of molecular analysis of combined sequence data for ITS, rpb2, tef1-α and tub2 and morphological characteristics, the strains were identified as L. pseudotheobromae (PH22-080), L. theobromae (PH22-120), and Lasiodiplodia sp. (PH22-060), which were confirmed to be pathogenic on cacao leaves, stems, and pods. L. theobromae (PH22-007) and L. hormozganensis (PH22-014) showed potential to cause disease in cacao but further investigation is needed.