The Effect of Chitinase on Didymella applanata, the Causal Agent of Raspberry Cane Spur light

Abstract

In vitro and in vivo studies were conducted to assess the efficacy of the two microbial chitinases Chi I (from Streptomyces sp.) and Chi II (from Serratia marcescens) on Didymella applanata (Niessl.) Sacc., the fungus which causes spur blight of raspberry (Rubus idaeus L.). D. applanata was isolated from canes of diseased raspberries in a plantation in Novosibirsk, Russia. In vitro, the effective concentration of Chi I that reduced the growth of D. applanata was 0.4 U/ml (p=0.05), but Chi II had no influence on the growth of the fungus in medium. In inoculation experiments on raspberry canes, both chitinases at the rate 0.5 U/ml reduced fungal development. In plantation where canes were inoculated after spraying with chitinase, fruiting bodies of fungus failed to form in all enzyme treatments, whereas a significant number of these fungal fruiting bodies (12.8 per cm 2 ) developed in control treatments lacking chitinases spraying. The chitinases reduced the size of lesions and limited the infection of internal tissues of canes. Field testing of Chi I under natural conditions showed a significant suppression of the independent spur blight. These studies form the basis for further evaluation of ecologically benign control measures for raspberry spur blight.

Binary Interactions of Antagonistic Bacteria with Candida albicans Under Aerobic and Anaerobic Conditions

“…However, in the presence of these crude preparations and prodigiosin from S. marcescens CAB 1094, we observed a significant decrease in the numbers of culturable yeast cells. These results support the findings of others who discovered that a number of fungi, including Didymella applanata [62], Fusarium oxysporum [65], Trichoderma reesei and Phycomyces blakesleeanus [56], are relatively resistant in vitro to the effect of S. marcescens chitinases. However, studies indicate that the co-inoculation of S. marcescens and Pseudomonas fluorescens enhances the antifungal activity of P. fluorescens towards F. oxysporum [65], and it was contented that this enhanced antifungal effect was a result of S. marcescens chitinase activity.…”

Toxicity of mancozeb, chlorothalonil, captan, fluopyram, boscalid, and difenoconazole toDidymella applanataisolates from Serbia

“…[7] However, even if all nonchemical measures are used, successful control of D. applanata inevitably requires fungicide treatments. [5,8] With few fungicides documented as effective in spur blight control many years ago (Bordeaux mixture, benomyl, captafol, captan, copper oxychloride, dichlofluanid, dithianon, ferbam, mancozeb, thiram and zineb), [4,[9][10][11] it is very difficult to make an appropriate fungicide selection. Beside insufficient number of available fungicides, many of these chemicals (benomyl, captafol, dichlofluanid, ferbam, and zineb) are not approved for further use in the EU region.…”

Changes in phenolic content induced by infection with Didymella applanata and Leptosphaeria coniothyrium, the causal agents of raspberry spur and cane blight

“…Both fungal diseases induce the development of necrotic lesions on raspberry canes that can cause premature cane or plant death in severe cases. Most authors report that infection is restricted to the outer bark tissue but others believe that the fungus may also invade the inner tissue (Williamson & Jennings, 1992;Shternshis et al, 2006). The diseases often blight the fruit-bearing spurs that are produced on the side branches, cause premature leaf drop and kill buds on the canes that later develop into fruit-bearing side branches.…”

“…Consequently, these diseases cause economi-cally important losses, which can be as high as 60% in years when climatic conditions are favourable for the development of the fungus (Williamson & Hargreaves, 1981). Growers try to counteract the impact of spur and cane blight with fungicide treatments or by the use of resistant or tolerant raspberry genotypes with improved phenolic compositions (Jennings, 1983;Shternshis et al, 2006).…”