Coexistence of «Candidatus Phytoplasmas asteris» and begomoviruses in Cuba: Case studies in Fabaceous crops

The emergency of diseases caused by begomoviruses and phytoplasmas continues increasing. In Cuba, «Candidatus Phytoplasma asteris» affect diverse hosts and the begomoviruses have emerged among the principal pathogens limiting the production of solanaceous and bean crops. Nowadays, studies for their individual identification are leading. However, there are unknown aspects such as their coexistence, the indicators of their presence, as well as the molecular identity of the possible agent associated with the symptom complex. In the last years, theobservation of diverse symptoms in the field, along with the incidence of whiteflies and high populations of leafhoppers, suggests the presence of mixed infections by these pathogens. Samples from symptomatic plants were analyzed. In bean crops, samples with predominant symptoms of golden yellow mosaic from the eastern and western regions of Cuba were collected. In soybean crops, samples showing diverse symptoms from the eastern region were evaluated. Technologies of nested PCR allowed detecting Candidatus Phytoplasma asteris in these plants.The RCA/RFLP’s methodology made possible the characterization of complete genomes of begomoviruses present in these crops. High indexes of infection by both pathogens were observed in individual detection and in mixed infections. The statistical analysis showed a high probability of co-infection occurrence when the presence of phytoplamas was detected in first instance. The high indexes in the coexistence of both entities suggest to detail into interaction studies among these that allow the design of major efficiency measures for the fabaceous cropsmanagement

First report of Alternaria alternata (Fr.) Keissler causing inflorescence blight in Jatropha curcas in Sinaloa, Mexico

A new fungal disease of inflorescences of Mexican nut (Jatropha curcas L.) was found on plants in two experimental fields located in Sinaloa, Mexico during summer 2011. The fungus caused inflorescence blight on flowers with typical symptoms of dark brown necrotic lesions; both plantations of J. curcas had disease incidence of 50–60%. Based on cultural and morphological characteristics and ribosomal DNA spacer sequences, the pathogen was identified as Alternaria alternata (Fr.) Keissler. To our knowledge, this is the first report of Alternaria inflorescence blight disease in J. curcas in Mexico

Empoasca papayae Oman, 1937 (Hemiptera: Cicadellidae) vector simultáneo de phytoplasmas y rickettsia asociadas a “Bunchy Top Symptom” en Cuba

Ensayos de transmisión mostraron desarrollo de síntomas típicos de BTS en todas las plantas de papaya después de tres meses de post-inoculadas con Empoasca papayae. El fitoplasma identificado en 28 de 45 las plantas inoculadas, presentó, en secuencia de ADN ribosomal 16S, un 99,9% igual al identificado en plantas de campo y con las detectadas previamente en E. papayae en Cuba. Todos son miembros del subgrupo de fitoplasma 16SrI-B. Una rickettsia se identificó en 41 de las 45 plantas inoculadas. Su secuencia parcial del gen sdhA mostró un 100% de identidad con la rickettsia identificada en plantas de campo, E. papayae y las previamente publicadas. Los resultados confirmaron la habilidad de E. papayae para transmitir simultáneamente el fitoplasma y la rickettsia.Abstract: Transmission trials showed typical BTS symptoms developed in all papaya plants after three months post-inoculated with Empoasca papayae. The BTS phytoplasma was identified in 28 out of 45 inoculated papayas, whose partial 16S rDNA sequence was 99.9% identical to those of the phytoplasma identified in the field-collected papayas, and that previously detected in E. papayae in Cuba. These are all members of the phytoplasma subgroup 16SrI-B. A rickettsia was identified in 41 out of 45 inoculated papayas. It showed a 100% of identity of its partial sdhA sequence to those from the field-collected papayas, E. papayae and the rickettsia previously identified. Results confirmed the ability of E. papayae to simultaneously transmit the BTS phytoplasma and the rickettsia pathogen

Coexistence of «Candidatus Phytoplasmas asteris» and begomoviruses in Cuba: Case studies in Fabaceous crops

The emergency of diseases caused by begomoviruses and phytoplasmas continues increasing. In Cuba, «Candidatus Phytoplasma asteris» affect diverse hosts and the begomoviruses have emerged among the principal pathogens limiting the production of solanaceous and bean crops. Nowadays, studies for their individual identification are leading. However, there are unknown aspects such as their coexistence, the indicators of their presence, as well as the molecular identity of the possible agent associated with the symptom complex. In the last years, theobservation of diverse symptoms in the field, along with the incidence of whiteflies and high populations of leafhoppers, suggests the presence of mixed infections by these pathogens. Samples from symptomatic plants were analyzed. In bean crops, samples with predominant symptoms of golden yellow mosaic from the eastern and western regions of Cuba were collected. In soybean crops, samples showing diverse symptoms from the eastern region were evaluated. Technologies of nested PCR allowed detecting Candidatus Phytoplasma asteris in these plants.The RCA/RFLP’s methodology made possible the characterization of complete genomes of begomoviruses present in these crops. High indexes of infection by both pathogens were observed in individual detection and in mixed infections. The statistical analysis showed a high probability of co-infection occurrence when the presence of phytoplamas was detected in first instance. The high indexes in the coexistence of both entities suggest to detail into interaction studies among these that allow the design of major efficiency measures for the fabaceous cropsmanagement

Gene Expression Profile of Mexican Lime (Citrus aurantifolia) Trees in Response to Huanglongbing Disease caused by Candidatus Liberibacter asiaticus

Nowadays, Huanglongbing (HLB) disease, associated with Candidatus Liberibacter asiaticus (CLas), seriously affects citriculture worldwide, and no cure is currently available. Transcriptomic analysis of host–pathogen interaction is the first step to understand the molecular landscape of a disease. Previous works have reported the transcriptome profiling in response to HLB in different susceptible citrus species; however, similar studies in tolerant citrus species, including Mexican lime, are limited. In this work, we have obtained an RNA-seq-based differential expression profile of Mexican lime plants challenged against CLas infection, at both asymptomatic and symptomatic stages. Typical HLB-responsive differentially expressed genes (DEGs) are involved in photosynthesis, secondary metabolism, and phytohormone homeostasis. Enrichment of DEGs associated with biotic response showed that genes related to cell wall, secondary metabolism, transcription factors, signaling, and redox reactions could play a role in the tolerance of Mexican lime against CLas infection. Interestingly, despite some concordance observed between transcriptional responses of different tolerant citrus species, a subset of DEGs appeared to be species-specific. Our data highlights the importance of studying the host response during HLB disease using as model tolerant citrus species, in order to design new and opportune diagnostic and management methods