MOLECULAR AND BIOCHEMICAL MARKERS ASSOCIATED WITH TOLERANCE TO Cassida vittata VILL (COLEOPTERA: CHRYSOMELIDAE) INFESTATIONS IN SUGAR BEET

Insect infestation of sugar beet is one of the most important problems in sugar beet fields at Delta, Egypt. Plant defense against insects represents the most successful element in integrated pest management (IPM). So, the behavior of insect attack, biochemical and molecular analysis were utilized to study protein, peroxidase and esterase isozymes banding patterns under insect attacks to sugar beet varieties. In addition, protein electrophoresis, genomic DNA (ISSR technique) and RAPD-PCR were used to find molecular markers associated with insect attack tolerance in sugar beet plants. These studies were carried out during 2012/2013 and 2013/2014 seasons on two sugar beet varieties (Pyramids and Zinagri). The insect attack behavior study showed that Pyramids variety is resistant to Cassida vittata and Zinagri variety is susceptible to Cassida vittata. From biochemical and genetic studies some peroxidase and esterase enzymes markers were found in the resistant variety. Presence of bands number 3 for peroxidase and number 5 for esterase can be considered as a marker associated with plant defense to Cassida vittata. Also, the bands with Mw 127 and 17.5 KDa can be considered as negative markers associated with plant defense to Cassida vittata, the band with Mw 80 KDa can be considered as a positive marker associated with plant defense to Cassida vittata. A high level of DNA polymorphism was detected by ISSR and RAPD-PCR techniques for the two sugar beet varieties showing some positive and negative markers associated with plant tolerance to insect attack.