Effects of silicon treatment and inoculation with Fusarium oxysporum f. sp. vasinfectum on cellular defences in root tissues of two cotton cultivars

BACKGROUND AND AIMS: Silicon has been shown to enhance the resistance of plants to fungal and bacterial pathogens. Here, the effect of potassium silicate was assessed on two cotton (Gossypium hirsutum) cultivars subsequently inoculated with Fusarium oxysporum f. sp. vasinfectum (Fov). Sicot 189 is moderately resistant whilst Sicot F-1 is the second most resistant commercial cultivar presently available in Australia. METHODS: Transmission and light microscopy were used to compare cellular modifications in root cells after these different treatments. The accumulation of phenolic compounds and lignin was measured. KEY RESULTS: Cellular alterations including the deposition of electron-dense material, degradation of fungal hyphae and occlusion of endodermal cells were more rapidly induced and more intense in endodermal and vascular regions of Sicot F-1 plants supplied with potassium silicate followed by inoculation with Fov than in similarly treated Sicot 189 plants or in silicate-treated plants of either cultivar not inoculated with Fov. Significantly more phenolic compounds were present at 7 d post-infection (dpi) in root extracts of Sicot F-1 plants treated with potassium silicate followed by inoculation with Fov compared with plants from all other treatments. The lignin concentration at 3 dpi in root material from Sicot F-1 treated with potassium silicate and inoculated with Fov was significantly higher than that from water-treated and inoculated plants. CONCLUSIONS: This study demonstrates that silicon treatment can affect cellular defence responses in cotton roots subsequently inoculated with Fov, particularly in Sicot F-1, a cultivar with greater inherent resistance to this pathogen. This suggests that silicon may interact with or initiate defence pathways faster in this cultivar than in the less resistant cultivar.

Novas linhagens de algodoeiro herbáceo com coloração na fibra.

No Brasil, o programa de melhoramento visando obtenção de cultivares com fibras coloridas foi iniciado pela Embrapa Algodão em meados da década de 1990 e até o presente momento já foram lançadas seis cultivares. Excetuando-se a BR 200, a primeira a ser desenvolvida e descendente de uma espécie de algodoeiro arbóreo (G. hirsutum L. r. marie galante Hutch.) as demais são de espécies de algodoeiro herbáceo (G. hirsutum L. r. latifolium Hutch.) e descendem do cruzamento de germoplasma de fibra colorida introduzido com germoplasma de fibra branca e adaptado ao cultivo na região Nordeste. Entre as cultivares desenvolvidas, há uma com fibra na cor verde e as demais possuem fibra marrom em diferentes tonalidades. Por outro lado, a espécie G. barbadense L. possui acessos silvestres com cores diferentes daquelas de G. hirsutum L., tais como lilás e marrom púrpura, além de outras. Há alguns anos a Embrapa Algodão vem trabalhando com estes materiais. Assim, o objetivo deste ?documento? é apresentar os resultados obtidos utilizando esta espécie com doadora de cores na fibra. O programa de melhoramento do algodão de fibra colorida da Embrapa objetiva a obtenção de cultivares com novas tonalidades de cores utilizando métodos convencionais de melhoramento.

O gênero geastrum pers. (phallomycetidae, basidiomycota) em algumas áreas de Mata Atlântica e Caatinga no Rio Grande do Norte, Brasil

A taxonomic survey of representatives of the genus Geastrum took place during the rainy season from 2006 to 2009 in four districts in the state of Rio Grande do Norte: Parque Estadual Dunas do Natal (Atlantic Forest), Mata do Jiqui EMPARN (Atlantic Forest) and Estação Ecológica do Seridó (Caatinga). Fourteen species were recorded: G. entomophilum, G. fimbriatum, G. hirsutum, G. javanicum, G. lageniforme, G. lloydianum, G. minimum, G. morganii, G. ovalisporum, G. pectinatum, G. saccatum, G. schweinitzii, G. setiferum and G. triplex. Of these species, eleven occurred in the Atlantic Forest and six in the Caatinga. A new species has been recorded to science, G. entomophilum, other as a first record for Brazil, G. morganii, six new records for the Northeast, and ten new records for Rio Grande do Norte. The material was tumbled in the Herbarium UFRN. Additionally, a survey of the species of the genus deposited in the Herbarium UFRN was accomplished, resulting in 244 herbarium specimens belonging to thirty-three species. Of these ones, twenty-three were collected in Brazil and ten are from Czech Republic, Europe, as donation from the VZ Herbarium

Mycosphaerella areola - the Teleomorph of Ramularia areola of cotton in Brazil, and its epidemiological significance.

2016