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This experiment was conducted to evaluate the effects of drought stress on some quality traits of tomato, seven tomato lines were assessed in an experimental field at Ilam University in 2016. The layout was split plots according to randomized complete block design (RCBD) with 3 levels of drought stress including 100, 60% and 40% of field capacity with 3 replications. The genotypes were including King stone, Peto early, Bitstoik, LA1607, LA2656, LA2080 and LA1579. The effect of mild and severe drought stress on the activity of antioxidant enzymes, including peroxidase, catalase and ascorbate peroxidase were investigated. The statistical analysis showed that drought stress significantly affected all assessed traits under drought condition. CAT, chlorophyll content and RWC were reduced, but, APX, POX, Proline and MAD content as well as electrolyte leakage increased and the highest content was observed under severe drought stress (40%FC). The genotypes LA1607, LA2656, LA2080 and LA1579 identified as the most tolerant and King Stone, Peto early and Bitstoik were the most susceptible genotypes. Under severe drought stress, the highest RWC in LA2080, POX in LA1579, APX in LA1607, Chlorophyll a in LA2080, Chlorophyll b in Peto early, Chlorophyll T in Bitstoik and LA2080, EL in LA2080, MDA in Bitstoik and prolin in Petoearly were observed.

An important strategy for obtaining a safer transgenic plant may be the use of a spatial- or tissue-specific promoter, instead of a constitutive one. In this study, we have used a light-inducible maize PEPC promoter to regulate the cry1Ab gene, aiming to produce transgenic potatoes that are resistant to potato tuber moth (PTM) (Phthorimaea operculella, Zeller). Out of 60 regenerated lines having normal phenotypes, 55 lines were PCR-positive for both the cry1Ab and nptII genes. Southern analysis on three selected putative transgenic lines revealed that they have only a single intact copy of the cry1Ab gene. An investigation of the Cry1Ab protein in the leaves and light-exposed (LE) tubers of the transgenic lines demonstrated the presence of the protein in the foliage and green tubers but not in the light-not exposed (LNE) tubers. A bioassay analysis of excised leaves of nine randomly selected lines showed that eight lines had 100% PTM larval mortality. Confirming results were obtained in six selected lines using the whole plant bioassay in the greenhouse. LE transgenic tubers also exhibited 100% larval mortality; however, the levels of damage to the LNE transgenic tubers were high and statistically the same as those incurred by the non-transgenic ones. Based on the results, we believe that this spatial expression of Cry1Ab using the light-inducible PEPC promoter can control PTM infestation in the field and significantly reduce pollution transmission to storage potatoes.

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