Marker-assisted selection for resistance to cassava mosaic disease in Manihot esculenta Crantz

Abstract

Cassava Mosaic Disease (CMD) is a very important disease that causes damage to cassava production. The objective of this research was to select cassava varieties resistant to CMD by using molecular markers. Two hundred fifty varieties collected from Rayong Field Crops Research Center were examined using molecular markers in the laboratory of Biotechnology Research and Development Office, Department of Agriculture from October 2017 to September 2019. In this research, 3 groups of molecular markers were used in selection for resistance to CMD. Group 1 included 4  Sequence Characterized Amplified Region (SCAR) and Simple Sequence Repeat (SSR) markers, namely RME1, NS158, SSRY28 and NS169 which are flanking nearby the CMD resistance gene called CMD2. Group 2 consisted of 2 molecular markers, namely EST-LRR and NB-ARC domains-containing disease resistance protein (EST-R protein) and EST-Protein kinase superfamily protein (EST-Kinase) which were obtained from the expressed sequence tags of genes in response to cassava mosaic virus, the cause of CMD. Group 3 contained 3 positions of Single Nucleotide Polymorphism (SNP) markers in Peroxidase gene, namely Ex2-78, Ex2-157 and Ex3-128. In total, 9 molecular markers were used to find out cassava varieties showing DNA band patterns and nucleotide sequences similar to those of the CMD resistant variety named TME3. The results of the experiment found that there were 2 varieties showing the same DNA band patterns and nucleotide sequences as TME3 in all 9 molecular markers, namely MMAL63 and CMR23-149-59. These varieties may be resistant to CMD. However, it is necessary to evaluate the resistance of these cassava varieties against the existing cassava mosaic virus before using such varieties for breeding and propagation to farmers.