Eight volatile products characterizing strawberry aroma, which is generated from the oxidative degradation of linoleic and linolenic acids by a lipoxygenase (LOX) pathway, were examined because of their antifungal activity against Colletotrichum acutatum, one of the causal agents of strawberry anthracnose. In this study, the effects of aldehydes, alcohols, and esters on mycelial growth and conidia development were evaluated. (E)-Hex-2-enal was found to be the best inhibitor of mycelial growth [MID (minimum inhibitory doses)=33.65 microL L(-1)] and of spore germination (MID=6.76 microL L(-1)), while hexyl acetate was the least effective of all volatile compounds tested (MID=6441.89 microL L(-1) for mycelial growth and MID=1351.35 microL L(-1) for spore germination). Furthermore, the antifungal activity of (E)-hex-2-enal on susceptibility of strawberry fruits to C. acutatum was also confirmed. The presence of these molecules in jars containing strawberry fruits inoculated with a suspension of spores inhibited the fungus growth and prevented the appearance of symptoms. Moreover, a study of the effects of (E)-hex-2-enal on conidial cells of C. acutatum was evaluated by transmission electron microscopy. This volatile compound altered the structures of the cell wall and plasma membrane, causing disorganization and lysis of organelles and, eventually, cell death.

Strawberry anthracnose, caused by Colletotrichum acutatum, is one of the most destructive disease of this crop throughout the world. Assymptomatic stages in the plant have been the aim of this work. Inoculated leaves samples were taken at different times and they were processed for scanner electron microscopy (SEM) and transmission electron microscopy (TEM). Conidial development on both surfaces leaves was determined. The ultrastructural study of fungus penetration into plant cell was characterized by the formation of vesicles over the fungus periphery and is a morphological parameter of the intense membranes traffic, also could be a evidence of a transcriptional activity and enzymatic cell secretion. Differences of symptoms on both surfaces of leaves were observed.

Strawberry anthracnose, caused by Colletotrichum acutatum J.H. Simmonds, is one of the most important diseases of this crop in Huelva (southwestern Spain). Lesions can occur on all parts of the plant but anthracnose crown rot is specially severe leading to wilt and death of plants. In this work, the infection and colonization process of C. acutatum on strawberry plants was studied. 'Camarosa' strawberry plants (highly susceptible to C. acutatum) were inoculated by applying 100 l droplets of a conidia suspension of the fungus on crowns, on buds and between second and third stipules. Plants were evaluated for response over a 30 days period. The severity of disease, estimated as percentage of plants showing symptoms on aerial parts, and the amount of infected crown tissues were determined at 2, 5, 10, 15, 20, 25 and 30 days after inoculation. Depending on the inoculation site the severity of anthracnose crown rot varied between plants. Moreover, an ultrastructural study of infected plants exhibiting anthracnose crown rot was carried out by transmission electron microscopy. The colonization of the crown tissues by intracellular and intercellular hyphae in the cortex, medulla and vascular system was observed resulting in cell colapse and necrosis.