Identification of ‘Candidatus Phytoplasma’ species in “huanglongbing” infected citrus orchards in the Caribbean

“Huanglongbing” (HLB) is one of the most devastating diseases of citrus orchards worldwide. Samples from 183 citrus plants of different cultivars and rootstock/cultivar combinations, showing HLB symptoms in three Caribbean countries (Cuba, Jamaica, and Guadeloupe-France), were collected to verify the possible co-infection of ‘Candidatus Phytoplasma’ and ‘Candidatus Liberibacter’ species. The 64% of the samples resulted positive to the ‘Ca. L. asiaticus’ and the 27% to diverse ‘Ca. Phytoplasma’-related species, moreover about the 14% of the samples infected with ‘Ca. Liberibacter’ were also found positive to phytoplasmas, indicating the presence of mixed infection especially in the orchards located in Cuba. Moreover, in one of the samples from Jamaica mixed phytoplasma infection was detected. Moreover the detection of only phytoplasmas in 11 symptomatic citrus samples collected from Cuba and Guadeloupe without ‘Ca. Liberibacter’ detection, confirmed that the symptomatology cannot be the sole criterium to discriminate between the presence of the two pathogens, and molecular detection is necessary to identify single or mixed infections. Diaphorina citri insects collected from Cuba and Guadeloupe resulted infected with ‘Ca. L. asiaticus’ confirming its active role in the dissemination of the pathogen. Only one insect of the Cicadidae family, collected in Guadeloupe, was found positive for phytoplasma presence. Considering that the phytoplasmas belonging to some ‘Candidatus species’ were detected in the three countries in different citrus varieties, a relevant role as phytoplasma reservoir can be attribute to citrus orchards

Detection of phytoplasmas in Passiflora edulis in Guadeloupe

During surveys in Guadeloupe a disease consisting in leaf dropping and vine drying in Passiflora edulis plants three years old plantation was observed. The affected plants were located near asymptomatic ones, however due to the high number of symptomatic plants the fruit production drastically decreased in 2017. Fruit from symptomatic and asymptomatic plants were collected and the peel was used for molecular investigation to verify possible phytoplasma presence. After PCR/RFLP analyses only the fruit collected from symptomatic plants resulted infected with two phytoplasmas enclosed in subgroups 16SrI-B and 16SrX-B. For the latter phytoplasma the molecular characterization on the aceF gene allow to confirm is identification as a \u2018Candidatus Phytoplasma prunorum\u2019-related phytoplasma strain. This is the first report of both phytoplasmas in passion fruit plants and one of the first reports of 16SrX-B phytoplasmas in cultivated not stone fruit species out of Europe

Identification of phytoplasmas in mango and pomegranate in Guadeloupe

Scattered plants in mango and pomegranate orchards in Guadeloupe showed disease symptoms consisting in branch and leaf dry and small and yellow leaves respectively. Fruits from symptomatic and asymptomatic mango and pomegranate plants were collected and the peel was used for a molecular investigation to verify the possible phytoplasma presence. After PCR/RFLP and sequencing analyses some of the fruits of both species resulted positive for phytoplasmas enclosed in subgroups 16SrI-B and 16SrI-F that in some of the samples were present in mixed infection