Confirmation of repulsion molecular markers linked to rhizomania resistance gene (Rz1) and evaluation of gene dose effect in sugar beet genotypes

Abstract

Rhizomania is the most important disease of sugar beet in Iran and some other parts of the world, and plays an essential role in decreasing sugar yield in fields. The best approach to control this disease is to use resistant varieties. For the involvement of resistance genes in breeding programs, tagging these genes by molecular markers is necessary. In this study, some breeding populations and commercial varieties of sugar beet originated from Rz1 resistance source were used for validation and repeatability of 6 repulsion molecular markers obtained from last studies. Accordingly, ELISA data related to greenhouse evaluation of rhizomania resistance were used in some breeding populations. DNA was extracted from leaf samples and RAPD-PCR was performed. The PCR products were separated by gel electrophoresis. After electrophoresis, the gel was stained with ethidium bromide and was observed using gel documentation device and finally was scored for the presence or absence of marker bands. In next step, adjustment of the markers with ELISA data in single plants was measured in breeding populations and the presence of markers in commercial varieties was determined. Comparison between ELISA and molecular analysis results showed that repulsion markers PN3 and PN7-2 had acceptable agreement with ELISA (92% and 98%, respectively), susceptible varieties (87% and 90%, respectively), and resistant varieties (75% and 97%, respectively). These markers were considered as the most suitable repulsion markers for identification of rz1 susceptibility allele. Also, the results of the gene dose effect showed that the ELISA OD mean values of the Rz1Rz1 genotypes was significantly lower than Rz1rz1 genotypes in the repulsion markers.

Keywords

• molecular marker
• rapd-pcr
• resistance
• rhizomania
• sugar beet