Abstract
The present study was conducted to assess whether exogenous applied salicylic acid (SA) as a foliar spray could ameliorate the adverse effects of virus infection in two maize cultivars (maize cv. sabaini and maize cv. Nab El-gamal). The plants were grown under normal field conditions for two weeks in sand clay soil, and then sprayed with either 2 or 4 mM SA. Two weeks later, plants were subjected to infection with two different concentrations of virus (TMV1 and TMV2), and were harvested 10 days later. Fresh and dry matter, shoot and root lengths, proline, soluble protein, soluble sugars as well as nitrate reductase activity were measured. Both fresh and dry matter were decreased under virus infection however, SA enhanced the fresh and dry matter production in both cultivars regardless the type of virus or SA concentration used. In roots, both fresh and dry matters were not affected. The shoot length was enhanced by salicylic acid than root length regardless the concentration used or virus treatment. The water content was much higher in shoots than roots especially in maize cultivar sabaini. Proline was accumulated in SA virus infected plants than reference control especially in cv sabaini. Soluble proteins and soluble sugars were accumulated in SA virus infected plants and in cv sabaini more than Nab El-gamal as compared with reference control. NRA was reduced in virus infected cultivars and cv sabaini was dramatically affected than Nab El-gamal. Treatment of plants with SA had a positive effect on preserving the activity of NR but was still less than the reference control regardless the cultivar used. Keywords: Nitrate reductase, proline, protein, salicylic acid, sugars, viruses. African Journal of Biotechnology Vol 13(23) 2330-2335
Highlights
The use of salicylic acid (2 and 4 mM) had different effects on both maize cultivars treated with different viruses
The relative water content of both shoots and roots of maize cultivar was increased in plants treated with salicylic and infected with viruses regardless the concentration used or virus treated (Table 1)
Maize is widely cultivated throughout the world and a greater weight of maize is produced each year than any other grain
Summary
The trigger for SA synthesis and induction of systemic acquired resistance is the recognition of an invading microorganism by a product of a resistance gene (Baker, 1997). Often, this recognition is accompanied by the hypersensitive response a form of rapid programmed host cell death in a region around the point of pathogen entry (Hammond-kosack and Jones, 1996). Salicylic acid, which is naturally synthesized by plants, plays an important role as a signal molecule that induces the tolerance mechanisms under the influence of both biotic and abiotic stresses such as virus, bacteria, fungi infections, freezing, drought, heat and heavy metals (Yalpani et al, 1994; Dat et al, 1998 Senaratna et al., 2000, Hussain et al, 2011). When plants are exposed to salt stress, they adapt their metabolism in order to cope with the changed environment
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