Abstract
The potato virus Y (PVY) is considered one of the most important viruses in terms of both economical and biological impact. Potential of using three different Streptomyces spp. crude filtrates (SCF) to induce of resistance against tuber necrotic strain of potato virus Y (PVYNTN) in four potato cultivars namely, Spunta, Nicola, Selatar, and Diamant, were evaluated. Foliar spraying of Streptomyces netropsis DSM 40093 (SCF7), S. ambofaciens (SCF11) and S. actuosus (SCF20), applied separately on potato cultivated in pots, showed various inhibitory activities against PVYNTN infection in all the potato cultivars. SCF20 was the most effective one, as expressed by (100%) reduction of apical necrosis symptoms on potato cv. Spunta, Nicola, and Diamant leaves under greenhouse conditions. Application was done 7 days before virus inoculation with PVYNTN (DBVI) and 7 days after inoculation (DAVI). The concentration of PVYNTN in treatments was significantly reduced than in the untreated PVYNTN infected plants as detected by DAS-ELISA (expressed by decreasing in OD value). Expression of PR-1b gene was detected 21 (DAVI) in all SCF11-treated cultivars but was not expressed in healthy and infected control plants. Gas chromatography-mass spectrometry (GC-MS) analysis of S. actuosus (SCF20) ethyl acetate extract revealed the majority of fatty acids (FAs) and their derivatives, Citroflex A, Hexanoic acid, anhydride, Hexadecanoic acid, Hexadecanoic acid, ethyl ester, and Diisooctyl phthalate which suggested to act as elicitor molecules for induction of systemic acquired resistance (SAR). Overall, the application of culture filtrates of Streptomyces has the potentiality to be used as inducer against PVYNTN infection.
Highlights
Potato (Solanum tuberosum L.) is known as the fourth largest food crop in terms of fresh production after rice, wheat, and corn, and the world’s most widely grown tuber crop
The present study aimed to evaluate the efficacy of different Streptomyces spp. crude filtrates (SCF) as bio-elicitors against PVYNTN infection under greenhouse conditions
In the present study, the potential activity of three different crude filtrates of Streptomyces spp. as bio-inducers (SCF) was assayed against PVYNTN infection for their ability to enhance the systemic acquired resistance (SAR) in four potato cultivars against the virus infection under greenhouse conditions. The evaluation of their activity was based on the disease severity, virus incidence in potato leaves, and the expression of pathogenesis related protein encoded for proteases (PR 1 gene)
Summary
Potato (Solanum tuberosum L.) is known as the fourth largest food crop in terms of fresh production after rice, wheat, and corn, and the world’s most widely grown tuber crop. Nasr-Eldin et al Egyptian Journal of Biological Pest Control (2019) 29:62 diverse of symptoms including severe necrotic ringspots on tubers and necrotic spots (local lesions), wrinkles and mosaic chlorosis on leaves, followed by newly deformed leaves, and the plant death (Warren et al 2005). The lack of an active defense response could be the main reason of virus spreading to neighboring cells causing disease symptoms, expressed by structural and physiological changes. A variety of passive and active defense mechanisms against plant pathogens including viruses were previously detected. Physiological, histological, and molecular analyses could be used for detection of such plant-pathogen interaction (Whitham et al 2006 and Nasr-Eldin et al 2018). Plant-pathogen interaction can set up a complex defense response, but sometimes could be neither rapid nor intensive enough to manage the viral spread replication. Plant’s natural defense mechanisms, e.g., systemic acquired resistance (SAR), could be induced using biotic or a biotic elicitors in order to control viral disease (Falcioni et al 2014)
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