Marcos C. Gonçalves

Sugarcane yellow leaf virus infection leads to alterations in photosynthetic efficiency and carbohydrate accumulation in sugarcane leaves

O virus do amarelecimento foliar da cana-de-acucar (Sugarcane yellow leaf virus, ScYLV) causa sintomas foliares severos e tipicos de infeccao por luteovirus, em cana-de-acucar (Saccharum spp.). Uma vez que alteracoes no sistema fotossintetico da planta seriam esperadas, avaliaram-se a analise da emissao da fluorescencia da clorofila a e as trocas gasosas durante a fotossintese, relacionando esses dados com analises metabolicas, ou seja, conteudos de pigmentos fotossinteticos e carboidratos presentes nas folhas. As plantas infetadas apresentaram reducao na eficiencia quântica fotoquimica potencial do fotossistema II (PSII) e alteracoes no preenchimento do pool de plastoquinona (PQ). Essas plantas apresentaram, tambem, reducao nas taxas de troca liquida de CO2, provavelmente em consequencia da reducao na eficiencia quântica. Paralelamente, reducoes nos conteudos de pigmentos fotossinteticos foliares e na razao clorofila a/clorofila b (chla/chlb) foram verificadas. Adicionalmente, o conteudo de acucares nas folhas foi aumentado, provavelmente como um efeito secundario da infeccao viral. A relacao entre a replicacao viral e as respostas de defesa da hospedeira com as alteracoes encontradas no aparelho fotossintetico e no metabolismo das plantas infetadas e discutida.

Infecção mista pelo Sugarcane mosaic virus e Maize rayado fino virus provoca danos na cultura do milho no estado de São Paulo

ABSTRACT Os dois principais virus que infectam o milho no Brasil sao o Sugarcane mosaic virus (SCMV) e o Maize rayado fino virus (MRFV),cujos principais vetores sao o afideo Rhopalosiphum maidis e acigarrinha Dalbulus maidis , respectivamente. O MRFV efrequentemente encontrado em infeccoes mistas com fitoplasmas eespiroplasmas, causando as doencas denominadas enfezamentos domilho. Em uma lavoura de milho proxima a Santo Antonio da Posse,SP, cercada por campos de cana-de-acucar, foi encontrada altaincidencia de plantas apresentando mosaico, riscas, nanismo e espigascom falhas no enchimento de graos. Analises serologicas com anti- Goncalves, M.C., Maia, I.G., Galleti, S.R., & Fantin, G.M. Infeccao mista pelo Sugarcane mosaic virus e Maize rayado fino virus provocadanos na cultura do milho no estado de Sao Paulo. Summa Phytopathologica , v.33, n.4, p.348-352, 2007. RESUMO soros especificos detectaram a presenca do SCMV e MRFV nessasplantas. A infeccao pelo SCMV tambem foi confirmada por RT-PCRcom primers especificos e analise de sequencias. Em observacoes depreparacoes contrastadas negativamente em TEM, particulas flexuosas(ca.770 nm) e isometricas (ca.30 nm) foram detectadas. Em cortesultrafinos, inclusoes citoplasmaticas, tipicas de

First Report of Maize yellow mosaic virus Infecting Maize in Brazil

Maize (Zea mays) is a staple crop for human consumption and widely used as a livestock feed worldwide. Therefore, potential new diseases affecting this crop are of major concern. In May 2013, yellow mosaic and dwarfing symptoms were observed in several maize plants in a field located in the rural area of Casa Branca (21° 46′ 26″ S, 47° 5′ 9″ W), Sao Paulo state (Southeastern Brazil). Symptomatic leaves were sampled, and total RNA was isolated using Trizol™ reagent and further purified with PureLink™ RNA Mini Kit spin columns (Invitrogen, USA). A library was prepared with an Illumina TruSeq Stranded Total RNA sample preparation kit with Ribo-Zero Plant and sequenced on an Illumina Hiseq2500 platform at Macrogen Inc, South Korea. De novo assembly using Abyss 1.9 with K-mer = 64 yieldeda contig of 1183 nt with high similarities (92-93%) to several isolates sequences of Maize yellow mosaic virus (MaYMV), a putative new member of the genus Polerovirus, family Luteoviridae, recently reported in China (Chen et a...

Screening Sugarcane Wild Accessions for Resistance to Sugarcane Mosaic Virus (SCMV)

In order to identify new sources of resistance for future introgression crosses, wild sugarcane germplasm was screened for resistance to Sugarcane mosaic virus (SCMV) under high inoculum pressure. Evaluation of symptoms by a grade scale associated with serological diagnostic by plate-trapped antigen-enzyme-linked immunosorbent assay (PTA-ELISA) with a specific antiserum were performed in 43 accessions, encompassing Saccharum officinarum, S. barberi, S. spontaneum and S. robustum species and hybrids. Differential patterns of resistance and susceptibility were observed among the Saccharum species, with S. officinarum followed by S. robustum accessions showing higher susceptibility, whereas S. barberi and S. spontaneum had the most resistant accessions. The results indicate that accessions IS76-155, IJ76-418 red, NG57-50, Ceram red, Badilla, Sac.off 8276, Fiji19, IJ76-313, US57-141-5, Krakatau, IN84-58, IN84-88, IN84-82, Gandacheni, and Chin, possibly consist in good sources of resistance to mosaic.