Speakers - PMBWC2025

Abstract

CLYD is a disease caused by a phytoplasm found in the phloem of infected plants, which blocks the vessels, preventing the transport of leaf sap to the hole plant. The phytoplasm transmission is carried out by vectors such as Myndus crudus (Van Duzee). It is recognized as one of the main threats to coconut production worldwide. In 1980, the pests were responsible for the death of more than 7 million palm trees in Jamaica. In Africa, the disease has been identified in countries such as Benin, Cameroon, Ghana, Kenya, Mozambique, Nigeria, Tanzania, and others. Mozambique has a high diversity of phytoplasm species associated with CLYD, namely: ‘Candidatus Phytoplasm palmicola’ 16SrXXII-A, Tanzanian lethal disease (LD) phytoplasm 16SrIV-C and a novel strain closely related to ‘Ca. Phytoplasm pini’ 16SrXXI-A, among others. In 2011 Mozambique had approximately 160,000 ha under coconut production, mainly in the provinces of Zambezia, Inhambane, Nampula and Cabo Delgado. Zambezia province had the highest acreage of coconut, with approximately 70% of the total area under the crop. From the total area of production, 80% of the crop was lost in the last 30 years. The aim of this study was to use molecular tools for identification of CLYD in commercial varieties of the biggest coconut producing regions in Zambezia province in Mozambique. Samples from stem and flowers were collected visually from symptomatic and asymptomatic plants in the regions of Mugaua, Gobene (Maganja da Costa), Murroa (Mugodoma), Tapata, Hode-tele (Mugela-Pebane) and Nangoela. For the purpose of the study, symptomatic plants were those who presented yellow-orange leaves, which began in older leaves, progressed to the younger ones, and finally to the crown, with the possibility of total discoloration or necrosis in the inflorescences not yet emerging as well as fruit drop. The samples were sent to the laboratory, were after catalogued, the DNA was extracted according modified CTAB Method. After the extraction, DNA quantification and molecular detection of the organism were applied by Polymerase Chain Reaction (PCR), using specific primers Phyto 14R/F that detect the CLYD strains circulating in Zambezia province. As a result, the plants in Mugaua, Gobene and part of Murroa plantations were positive for the pathogen causing the disease, even in the samples that visually was healthy being the predominant coconut varieties the Duarf green, Hybrid and Sri lanka Tall Green and Red, considered susceptible. While areas of Murroa, Tapata and Hode-Tele, did not detect the presence of the pathogen, including samples that showed symptoms with predominant coconut varieties are the Mozambican Tall (MZT) Bronze and Green. Nangoela region variety made up of coconut hybrids showed the absence of pathogen, although considered susceptible. Therefore it can be concluded that molecular identification is a reliable method for CLYD identification, although more research is needed for varieties molecular characterization and provide more information on the tolerant and resistant genes for CLYD.
Keywords: Coconut, CLYD, Phytoplasm, PCR, Zambézia