Journal of Pure and Applied MicrobiologyVol. 8 No. Special Edition Nov. 2014

Characterization of Alternaria Isolate from Organically- Grown Tomato (Lycopersecon esculentum L.) in Relation to the Fruit Antioxidant Compounds

Afrah E. Mohammed, Eman A. H. Alhomaidi and Dalal H. M. Alkhalifa

Department of Biology, Faculty of Science, Princess Nourah Bint Abdulrahman University, Postal Code 11474, Riyadh, Saudi Arabia.

Received on 03 September 2014 and accepted on 12 October 2014

 

ABSTRACT

Environmental pollutionas a consequence of irrational usage of fungicides is an immense problem bothering the well-being of human kind globally. The real risk is the possibility of such pollutants to ultimately find their way to human food via food chain. Recently, a growing concern regarding food safety has increased in response to the high demand for organic products. Organic tomato cultivation gainedgreat preference and acceptability for consumers. However, contamination of fresh fruits and vegetables with a variety of postharvest fungi is an essentialproblem which requires immediate measures to be taken seriously for the sake of maintaining human health.The main objective of this work is to study the susceptibility of organically-cultivated tomato fruit to post harvest pathogenic fungi and to find out whether there is relationship between total phenolic compounds, ascorbic acid content and antioxidant capacity of tomato fruit and the appearance of fungal growth. Furthermore, DNA-based method, Random amplified polymorphic DNA technique (RAPD) was used to fingerprint and assess the genetic informationabout thefungal isolate. The current results revealed that different tomato varieties showed different susceptibility levels to infection by postharvest pathogenic fungi besides different amounts of accumulated total phenolic compounds, ascorbic acid contentand antioxidant capacity. Furthermore, higher concentrations of total phenolic compounds,ascorbic acid content andantioxidant capacity were detected in the small size tomato fruit, which might point to absence of fungal growth. Furthermore, morphological characteristics showed that the isolate detected from infected tomato fruit was alternaria alternata, finger print (RAPD) technique showed clear DNA bands for the isolate which indicated that the opa04 was an efficient primer that supported the amplification by producing unique patterns of banding for the A. alternata isolate. Further molecular work is needed to provide more authenticated information regarding the isolate.

Keywords : Lycopersecon esculentum, antioxidants, alternaria alternata, RAPD