Alves, A.A.C.

Bellotti, Anthony C.

Dita, M.A.

Fregene, Martin A.

Silva, A.F.

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Cassava wild species: Diseases evaluation in different regions of BrazilDita, Miguel1; Alves, Alfredo1; Silva, Alineaurea2; Bellotti, Anthony3; Fregene, Martin31Embrapa Cassava & Tropical Fruits, Cruz das Almas, Bahia, Brazil; 2Embrapa Semi-Arid, Petrolina, Pernambuco, Brazil; 3International Center for TropicalAgriculture, Cali, Colombia. e-mail: miguel@cnpmf.embrapa.br• Cassava wild relatives are reservoirs of useful genes to be transferred tocultivated cassava, but…• The number of identified traits, such as disease resistance, is low considering theexistent diversity. Thus,• This work aimed to evaluate disease incidence and severity in cassava wildspecies in order to identify sources of resistance for introgression in elite cassavacultivars.Seedlings of different accessions of M. anomala (Fig. 1A), M. flabellifolia (Fig. 1B),M. glaziovii (Fig. 1C), M. peruviana (Fig. 1D) e M. dichotoma (Fig. 1E) planted inSão Miguel das Matas (SMM), Tancredo Neves (TN) and Cruz das Almas (CA), inthe Bahia State and in Petrolina (PT) in the Pernambuco State were evaluatedmonthly from 6 to 12 month after planting. SMM, TN and CA are characterized assubhumid environments with different annual average rainfall varying from 1000 to1800 mm and PT is representative of the semi-arid (around 560 mm).In all the regions cultivars of M. esculenta were planted as comparison pattern andinoculum source. Severity of anthracnose, rust and brown leaf spot was assessedusing scales from 0 to 5 class (0: no symptoms and 5: maximum level of susceptibility).ResultsFig. 1. Cassava wild species. A) M. anomala. B) M. flabellifolia C) M. glaziovii. D)M. peruviana. E) M. dichotomaAll the pathogens identified in wild species are common to cultivated cassava (M.esculenta).  However, disease symptoms can be different, such as brown leaf spot(BLS) in M. anomala (Fig. 2A & 2B) and in  M. glaziovii (Fig. 2C & 2D). In BahiaState the incidence of brown leaf spot (Cercosporidium henningsii), white leaf spot(Phaeoramularia manihotis), diffuse leaf spot (Cercospora vicosae), anthracnose(Colletotrichum gloesporioides f. sp. manihotis) and rust (Uromyces spp.), wasrecorded (Fig. 2). In Petrolina, however, only sporadic lesions of BLS were found.BLS was the disease with the highest incidence and severity, being more intensein São Miguel das Matas, Tancredo Neves and Cruz das Almas, respectively(Table 1).Regarding BLS severity, both inter- and intraspecific differences were observed(Fig. 3). The other diseases showed lower values than BLS, ranging from classes1 to 2 of the evaluation scale (data not shown). Regardless of localities, accessionsof M. glaziovii  were more susceptible and of M. flabellifolia more resistant (Table1; Fig. 3).For all the evaluated diseases, accessions with high level of resistance wereidentified. These accessions are excellent candidates, not only to be used asresistance sources for cassava breeding, but also for studies addressed tounderstand genetic and molecular basis of disease resistance in cassava.SÃO MIGUEL DAS MATAS50.0078.0050.000.0085.00Rust50.0042.0031.000.0014.00Anthracnose0.007.000.000.000.00Diffuse leaf spot0.0075.0075.0060.0028.20White Leaf spot100.00100.00100.00100.00100.00Brown leaf spotM. glazioviiM. peruvianaM. flabellifoliaM. dichotomaM. anomalaDisease/SpecieTANCREDO NEVES0.0070.0085.0029.4037.50Rust0.0089.0070.000.0037.50Anthracnose0.000.005.000.0025.00Diffuse leaf spot14,2867.50         80.000.0050.00White leaf spot100.00100.00100.0094.00100.00Brown leaf spotM. glazioviiM. peruvianaM. flabellifoliaM. dichotomaM. anomalaDisease/SpecieCRUZ DAS ALMAS5.880.000.004.000.00Rust0.0015.0010.000.000.00Anthracnose5.8814.2866.60.007.00Diffuse leaf spot5.8842.800.000.007.00White leaf spot10010010037.5092.30Brown leaf spotM. glazioviiM. peruvianaM. flabellifoliaM. dichotomaM. anomalaDisease /SpecieTable 1. Disease incidence (%) in cassava wild species in different regions ofBrazilFig. 2. Symptoms of disease in cassava wild species. Brown leaf spot in M.anomala (A & B), M. glaziovii (C & D) and M. peruviana (E & F). Anthracnose in M.peruviana (G & H). Rust in M. flabellifolia ( I & J).  Diffuse leaf spot (K) and Brownleaf spot in M. peruviana (L).IntroductionMethodologyFig. 3. Severity (in class from 0 to 5) of brown leaf spot in different accessions ofcassava wild species in São Miguel das Matas, Bahia, BrazilA BC DE FG HI JK LA B D EC012345M. anomala M. dichotoma M. flabellifolia M. glaziovii M. peruvianaSeveridade (NotasSeverityMinistry ofAgriculture, Livestockand Food Supply

Cassava wild species: diseases evaluation in different regions of Brazil

Rodríguez, M.A.D.

https://cgspace.cgiar.org/bitstream/10568/58096/1/poster_dita-wild.pdf

Cassava wild species: diseases evaluation in different regions of Brazil

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