2,4-Dichlorophenoxy acetic acid, abscisic acid, and hydrogen peroxide induced resistance-related components against potato early blight (Alternaria solani, Sorauer)

AbstractInduction of acquired resistance activates defense-related genes. Current study aimed to (a) initiate potato acquired resistance to the Early Blight disease caused by Alternaria solani through treating potato plants with low and repetitive doses of 2,4-dichlorophenoxy acetic acid (2,4-D), abscisic acid (AB), and hydrogen peroxide (H2O2) and (b) test the success of the use of the chemical inducers along with the application of fungicides. Potato cultivars Nicola and Spunta were treated once per wk for 6wk and challenged 1wk later by in the control of A. solani. Results showed that peroxidase (POD), phenylalanine ammonia lyase (PAL), and polyphenoloxidase (PPO) enzyme activities and gene regulation were significantly increased after 1d of infection and lasted for more than 15d. The 2,4-D and H2O2 inducers significantly increased both enzyme activities and gene expression of PAL, PPO, and POD for more than 15d post inoculation. PAL was the most increased at the enzyme activity and gene expression levels. Incorporation of such in-expensive treatments might reduce management costs and reduce the environmental pollution

Identification and Reconsidering Phylogeny of Some Aphid Species, (Hemiptera: Aphididae), Based on Molecular DNA Markers Using ISSRs-PCR Technique

Aphids are considered one of the most economically important insect pests worldwide. Successful pest management systems are based on accurate and rapid pest species identification. Traditional morphological identification of closed aphid species may be considered an inaccurate taxonomic process. To overcome the disadvantages of traditional morphological identification, molecular techniques, related to DNA markers and based on polymerase chain reaction (PCR), were approached by using nine ISSRs primers to identify and diagnose fifteen common aphid species that disperse in the Egyptian agroecosystem. The examined ISSRs primers could success-fully discriminate the tested aphid species that reflected 61.39% polymorphism among them. Moreover, four banding patterns were considered unique bands that could characterize three aphid species (Aphis gossypii, Aphis nerii and Myzus persicae). The highest genetic homology (84.9%) was observed between species Rhopalosipum padi and Schizaphis graminum. In addition, each of A. gossypii and Aphis citricola were also genetically homologous species. In contrast, species Aphis craccivora and M. persicae were analogous genetically with a low similarity percentile (59.8%). High genetic di-vergence was observed also between A. nerii and M. persicae. Two alternative molecular branching taxonomic keys were proposed by subjecting the five highest polymorphic ISSRs primers and 29 banding patterns with different molecular sizes