Genetic structure in populations of the fungus Fomitiporia punctata associated with the esca syndrome in grapevine

Six populations of Fomitiporia punctata (Fr.) Murrill were sampled in France and Italy from vines showing symptoms of esca syndrome. Genetic variation within and among populations was studied by using 34 random amplified polymorphic DNA (RAPD) markers. All the 192 isolates analyzed were distinguished, and the haplotypic diversity was similar in each population. The hypothesis that markers were randomly associated was not rejected for 5 populations and for the total sample. Comparison of marker frequency showed significant differences among populations for only 4 markers, indicating a low level of genetic differentiation. The analysis of molecular variance (AMOVA) confirmed that most of the variance in RAPD banding patterns was present within populations (98.5 %). These data strongly suggest that the fungus spreads by means of airborne basidiospores and regularly outcrosses in nature. The prospected regions seem to form an epidemiological unit with a panmictic population of F. punctata. However, a very low but significant differentiation was detected between the populations in western France and those in Mediterranean locations.

Comparison of responses of ascospores and mycelium by ELISA with anti-mycelium and anti-ascospore antisera for the development of a method to detect Sclerotinia sclerotiorum on petals on oilseed rape

International audienc

Genetic structure in populations of the fungus Fomitiporia punctata associated with the esca syndrome in grapevine

International audienc

Symptoms, wood lesions and fungi associated with esca in organic vineyards in Languedoc-Roussillon (France)

We analysed symptoms, wood lesions and fungi associated with esca in mature organic vineyards in the Languedoc-Roussillon region. Most previous surveys concerning esca syndrome were conducted in conventionally managed vineyards in other regions. We first found that esca may be present at a very low level in vineyards that were not treated with sodium arsenite. Affected vines displayed three types of symptoms: leaves with interveinal necrosis, wilt of entire branches and these two symptoms in combination. During the 3-year survey, not all affected vines displayed symptoms every year and the same vine rarely displayed the same symptom or combination of symptoms in successive years. The incidence of esca appeared to be correlated with the percentage of vines that died during the survey but no correlation was found with either mortality before the survey or with the age of the vineyard. Observation of cross-sections of a total of 210 vines with esca symptoms and isolation of fungi from the wood lesions led to similar results to those obtained in conventionally managed vineyards. Four different lesions were identified: a white rot lesion, a brown lesion in a central position, a brown lesion in a sectorial position and a scattered black spotting in healthy wood. The most frequently observed fungal species were Fomitiporia mediterranea (Fom), Phaeomoniella chlamydospora, Phaeoacremonium aleophilum and Eutypa lata. The white rot lesion caused by Fom was generally accompanied by one or more other lesions in the same vine. Similarly, Fom was generally isolated with one or several other fungi. No relationship was detected between the expression of external symptoms and any specific lesion or fungus. Our study also showed that esca and Eutypa dieback are often superimposed in our region of samplin

Population genetics of fungi associated with esca disease in French vineyards

International audienc

Genetic diversity in populations of the fungi Phaeomoniella chlamydospora and Phaeoacremonium aleophilum on grapevine in France

International audienc

Diversity of the grapevine dieback fungus Eutypa lata in France

National audienc

Agronomic performance of sugarcane families in response to water stress Desempenho agronômico de famílias de cana-de-açúcar em resposta ao déficit hídrico

Water deficit is one of the major factors limiting the production of sugarcane, especially in areas where there is a prolonged period of water deficiency, such as the West Central Brazilian region. One way to overcome this problem is to cultivate resistant or tolerant varieties. An experiment was set up at the Jalles Machado Sugar Mill, located near Goianésia, Goiás State, Brazil, to evaluate agronomic performance of several sugarcane families. A comparative analysis was carried out among the families under two irrigation regimes, one under regular environmental conditions and another under monthly irrigations during the period of water deficiency. Evaluated families consisted of 25 progenies planted in a factorial design with three replications with 20 plants each. The first ratoon crop was evaluated for four yield components, stalk height, stalk diameter, stalk number and Brix. By analysis of variance, stalk number and stalk height were influenced by water stress conditions during the initial growth phase, and for stalk diameter and Brix, water regime had no effect on the average expression of the characters during the growth phase. The method of classification in four categories proved to be adequate. Some families had high values for stalk diameter, stalk number and stalk height under water stress conditions. This study showed that it is possible to select sugarcane families under water deficit conditions associated with higher stalk diameter, stalk number and stalk height.<br>O déficit hídrico é um dos fatores mais importantes que limitam a produção da cana-de-açúcar, especialmente nas áreas onde existe um período prolongado de seca, como na Região Centro-Oeste do Brasil. Uma forma de contornar este problema é plantar variedades resistentes ou tolerantes à seca. Um experimento foi desenvolvido na Usina Jalles Machado, localizada próxima de Goianésia, no Estado de Goiás, Brasil, para avaliar o desempenho de várias famílias de cana-de-açúcar sob condições de déficit hídrico. Foi realizada uma análise comparativa entre as famílias que foram cultivadas sob duas condições de disponibilidade de água: ambientais regulares ou irrigações mensais durante o período de deficiência de água. O material avaliado consistiu de 25 famílias plantadas em um desenho factorial de três repetições com 20 plantas cada uma, no total de 60 indivíduos. Na colheita da primeira soqueira, avaliaram-se quatro componentes: altura, diâmetro, número de colmos e Brix. Por meio da análise de variância, o número e a altura dos colmos foram influenciados pelas condições de seca durante a fase de crescimento inicial, enquanto o regime de irrigação não afetou as médias de diâmetro do colmo e de Brix durante a fase de crescimento. Pelo método de separação em quatro categorias, em algumas famílias observaram-se elevados valores de diâmetro, número e altura de colmos quando cresceram sob condição de déficit hídrico. Este estudo comprovou que é possível selecionar famílias de cana-de-açúcar sob estresse hídrico associadas com maiores diâmetro, número e altura de colmos