Identification of Bipolaris bicolor and Bipolaris sorokiniana on wheat seeds (Triticum aestivum L.) in Brazil

Abstract

Diseases caused in wheat by Helminthosporium spp. have led to considerable yield and production losses. Different species in this genus are associated with wheat seeds. In Brazil, spot blotch in wheat is caused by Bipolaris sorokiniana (Sacc) Schoem, and another fungus Bipolaris bicolor (Mitra) Shoem that has been also isolated from wheat seeds. The current study was undertaken to identify the most frequent fungus species that normaly infects wheat seeds and compared them with B. sorokiniana. The fungus Bipolaris bicolor (Mitra) Shoem., isolated from wheat seeds cultivar IAPAR, was identified by taxonomic methods and compared with the fungus Bipolaris sorokiniana (Sacc.) Shoem., in relation to growth characteristics on the seeds, as well as to growth characteristics in PDA and morphology of the structures. Type of colony observed on the seeds is important for the differentiation between the fungus species. Bipolaris sorokiniana presented black colonies, which were well-adherent to the seeds, whereas B. bicolor presented grayish, aerial, cottonlike colonies. The size of the conidia also differed in length and width, and B. bicolor presented the smallest dimensions. In relation to septa, B. bicolor conidia presented deep ones, with dark color bases, but seldom presented dark apex. Bipolaris sorokiniana presented homogenous color.

<i>Helminthosporium bicolor</i>, un pathogène foliaire du riz et de <i>Stenotaphrum secundatum</i> au Maroc

“…Helminthosporium bicolor a été découvert en Poona (Inde) en même temps que la découverte de la carie du blé (Mitra, 1930). L'espèce est signalée parmi la mycoflore des semences du riz (Nenínger et al, 2003) et du blé (Morejón et al, 2006). Mais depuis lors, aucune étude n'a été réalisée pour confirmer ou non les aptitudes pathogènes de ce champignon sur les feuilles du riz.…”

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“…Metode isolasi yang digunakan adalah direct plating (Morejon et al, 2006) dan moist chamber (Defitri, 2013). Karaterisasi cendawan dilakukan menurut Morejon et al, (2006).…”

“…Metode isolasi yang digunakan adalah direct plating (Morejon et al, 2006) dan moist chamber (Defitri, 2013). Karaterisasi cendawan dilakukan menurut Morejon et al, (2006). Karakterisasi dan Identifikasi berdasarkan karakter makroskopis meliputi: bentuk koloni tua, warna koloni tua, tekstur koloni tua, bentuk koloni muda, warna koloni muda, dan tekstur koloni muda.…”

“…berkisar 38.3-65.8 µm x 12.3-25 µm dengan bentuk konidia yang sedikit melengkung, konidia berwarna coklat sampai berwarna kuning langsat coklat dengan 2-13 sekat. Menurut Morejon et al (2006) Helminthosporium sp. pada media PDA saat diinkubasi pada suhu 25°C tampak koloni seperti beludru, warna koloni hitam zaitun (hitam kehijauan), miselium tidak ada, konidiofor pendek.…”

Mancha foliar em capim-elefante no Cerrado do Brasil Central causada por Bipolaris maydi

“…Butler) Shoemaker, em Pernambuco (Reis et al, 1997), e o carvão causado por Ustilago kamerunensis P.&H. Sydow, no Leste da África, particularmente no Quênia (Farrel et al, 2002) O isolamento do agente etiológico foi efetuado a partir de folhas lesionadas, em meio de BDA + estreptomicina. A cultura monospórica de Bipolaris sp., proveniente desse isolamento, foi enviada ao serviço de identificação do CABI Bioscience, Egham, Surrey, Reino Unido, para identificação da espécie, além de se usar a literatura especializada para comparação das características morfológicas do isolado (Alcorn, 1983;Bach & Kimati, 2004;Morejon et al, 2006).…”