Submitted to: Pakistan Journal of Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/30/2008
Publication Date: 9/1/2008
Citation: Alvi, A.K., Iqbal, J., Shah, A.H., Pan, Y.-B. 2008. DNA Based Genetic Variation for Red Rot Resistance in Sugarcane. Pakistan Journal of Botany. 40(4):1419-1425.
Interpretive Summary: The red rot fungal disease is one of the major sugarcane production constraints in Pakistan. The best and most direct approach to control this disease in sugarcane is to grow varieties that are resistant to red rot. However, disease screening during selection and field evaluation is tedious and costly. This study was conducted to identify DNA fragment(s) (molecular markers) that are linked to the resistance gene for red rot. Genetic variability among twelve resistant and five susceptible Pakistani varieties was assessed with one class of molecular markers called random amplified polymorphic DNA or RAPD. A total of 300 different RAPD markers were initially tested on two resistant and two susceptible varieties. From these tests, 24 markers were chosen to assess all 17 varieties with the amplification of 182 DNA fragments. Of these fragments, 26 were common to all of the varieties and 156 were produced by some but not all the varieties. There was no correlation between any of these 156 fragments and either resistance or susceptibility to red rot. A high level of genetic similarity (74%) was detected among the 17 Pakistani varieties. The study suggests that there may be more than one gene for red rot resistance.
Technical Abstract: Genetic difference between twelve red rot resistant and five susceptible genotypes of sugarcane cultivated in Pakistan were studied using Random Amplified Polymorphic DNA (RAPD) markers. Initial screening was done using 300 markers and four genotypes (two resistant and two susceptible for red rot). From these 300 markers, 24 were selected and further applied to all 17 genotypes. A total number of 182 loci were generated by these 24 primers. Of these 156 loci were polymorphic and 26 were monomorphic, whereas 10 loci were genotype specific. Moreover, the number of monomorphic loci for the resistant and susceptible genotypes was 29 and 52 respectively. However, none of the loci could be solely linked to either resistance or susceptibility against red rot. The mean genetic similarity among the genotypes recorded was 74.37% which shows that a large part of the genome similar. This may be due to the lack of parental diversity. This study reveals that there is possibly more than one genetic reason for the resistance or susceptibility against red rot in sugarcane genotypes of Pakistan.