ABSTRACT
A survey to investigate the occurrence of cassava anthracnose disease (CAD) and distribution of Colletotrichum spp. in cassava plantations in different eco-zones of the Reconcavo Region in Bahia, Brazil, investigated during the rainy season of 2014. A total of 50 cassava fields distributed among 18 municipalities were visited and intensity of anthracnose evaluated. The highest disease incidence (DI) (83.3%) was in samples collected in São Félix, and the lowest (34.4%), in Varzedo. Municipalities that presented the highest values for DI were located within the 'Af' Köppen-Geiger eco-zone, also presenting the highest values for the estimated McKinney disease index. Based on previous studies of multilocus phylogeny, seven different species of Colletotrichum were identified (Colletotrichum fructicola, Colletotrichum tropicale, Colletotrichum gloeosporioides s.s, Colletotrichum theobromicola, Colletotrichum siamense, Colletotrichum brevisporum and Colletotrichum plurivorum) and a new approach based on ERIC-PCR was used aiming to group the 82 isolates according to these findings. The highest percentage of genetic variance (> 78%) was among isolates within fields. Based on the survey and genetic analysis, C. fructicola is probably the main causal agent of cassava anthracnose in the Recôncavo Region, since this species was present with highest incidence in all eco-zones, 47.61, 42.86 and 57.14% for Af (tropical rainforest climate), As (tropical dry savanna climate) and Aw (tropical wet savanna climate), respectively. This study is the first report of C. fructicola lineages as the most likely pathogen causing anthracnose disease of cassava in Brazil, and these findings may be used to guide the selection of resistant varieties.
ABSTRACT
O objetivo deste trabalho foi avaliar linhas quase isogênicas de trigo com o caráter permanência verde e de maturação sincronizada quanto à tolerância ao alumínio e à sensibilidade ao ácido giberélico (AG3). O experimento foi conduzido no Laboratório de Duplo-haplóides e Hidroponia da FAEM/UFPel, em delineamento de blocos ao acaso, com parcelas subdivididas com três repetições, através do teste simultâneo utilizando solução nutritiva com concentrações de 10mg L-1 de Al3+ e 100mg L-1 de AG3. Foram determinados: a inserção da 1ª folha, o comprimento da 1ª folha, a inserção da 2ª folha, comprimento da 2ª folha, diferença da inserção entre a 1ª e 2ª folha, estatura de plântula, estatura de planta, área foliar, área radicular e o crescimento de raiz. Os caracteres estatura da plântula, inserção da 1ª folha e comprimento da 2ª folha foram os mais expressivos para a seleção de indivíduos com estatura reduzida através da reação do AG3. O grupo do caráter permanência verde apresentou maior insensibilidade à ação do AG3, enquanto o grupo de plantas sincronizadas proporcionou maior tolerância ao Al3+. Contudo, existe possibilidade de selecionar linhas quase isogênicas dentro do grupo permanência verde com tolerância ao Al3+ e insensibilidade ao AG3 através da técnica de cultivo hidropônico com solução nutritiva em ambiente controlado.
The objective was to evaluate wheat near-isogenic lines differing from the trait stay-green and synchronized maturation regarding their alluminum tolerance and sensibility to the giberellic acid (GA3). The experiment was conducted in the Double-haploids and Hydroponics Laboratory of FAEM/UFPel, in random block with split plot design with three replications, using the simultaneous test in nutrient solutions with 10mg L-1 of Al3+ and 100mg L-1 of GA3. The following characters were evaluated: insertion of the 1st leaf, length of the 1st leaf, insertion of the 2nd leaf, length of the 2nd leaf, difference between the 1st and 2nd leaf insertion, seedling stature, plant stature, leaf area, root area and root growth. The characters seedling stature, insertion of the 1st leaf and length of the 2nd leaf were the most expressive for the selection of individuals with reduced stature caused by the GA3. The group stay-green presented higher insensibility to GA3 compared to the group of synchronized plants showed larger tolerance to Al3+. However, it is possible to select near-isogenic lines within the stay-green group with Al3+ tolerance using hydroponic culture under controlled environmental conditions.
