Breeding work utilizing both genotypic and phenotypic· markers is the most effective way of achieving target. Molecular markers eg
restriction fragment length polymorphism (RFLP), single nucleotide polymorphism (SNP) and simi'~~ sequence repeat (SSR) tightly
linked to target gene have been identified in different chromosomes to impose the genetic selection ie marker assisted selection
(MAS). This paper summarize the progress and achievement made in breeding for blast resistance based on DNA markers which
help in planning blast resistance gene tagging in Nepalese rice genotypes and developing blast resistant inbred line or near isogenic
line (NIL). Blast fungus (Pyricularia oryzae Cav.) can infect plants at any growth stage from seedling to maturity and at any part eg
leaf, node, internode, neck and seed. Qualitative resistance gene may occasionally be broken down due to numerous races of blast
fungus both physiological and geographical races available in Nepal. Quantitative gene resistance and gene pyramiding are the best
alternative for creating durable resistance system. At least 40 genes conferring resistance to blast isolates with multiple alleles have
been described. Both dominant and recessive resistance alleles have been found in many rice landraces. Morphological and isozymic
markers are limited in number. Therefore, highly polymorphic and easily detectable SSR markers are being used in breeding for
blast resistance. Bulked segregant analysis (BSA) is the simple method for tagging resistance ge~e by SSR markers. Quantitative
trait loci (QTLs) have also been mapped and· most of them are linked to qualitative genes. SSR markers linked to the gene are being
used to select plants possessing the desired trait and markers throughout the genome are being used to select plants that are
genetically similar to recurrent parent. Using SSR markers it may be possible to select blast resistance genotypes at any stage of crop
development from any small part of crop, to conduct many round of selection, to select without inoculums, without scoring, and
without testing in hot spot or artificial inoculation. Molecular based blast resistance breeding work is initiated focusing on resistance
gene tagging in Nepalese rice Iandraces and transferring resistance genes in cvs Jumli Marshi, K.humal-4 and Mansuli.

Breeding work utilizing both genotypic and phenotypic· markers is the most effective way of achieving target. Molecular markers eg
restriction fragment length polymorphism (RFLP), single nucleotide polymorphism (SNP) and simi'~~ sequence repeat (SSR) tightly
linked to target gene have been identified in different chromosomes to impose the genetic selection ie marker assisted selection
(MAS). This paper summarize the progress and achievement made in breeding for blast resistance based on DNA markers which
help in planning blast resistance gene tagging in Nepalese rice genotypes and developing blast resistant inbred line or near isogenic
line (NIL). Blast fungus (Pyricularia oryzae Cav.) can infect plants at any growth stage from seedling to maturity and at any part eg
leaf, node, internode, neck and seed. Qualitative resistance gene may occasionally be broken down due to numerous races of blast
fungus both physiological and geographical races available in Nepal. Quantitative gene resistance and gene pyramiding are the best
alternative for creating durable resistance system. At least 40 genes conferring resistance to blast isolates with multiple alleles have
been described. Both dominant and recessive resistance alleles have been found in many rice landraces. Morphological and isozymic
markers are limited in number. Therefore, highly polymorphic and easily detectable SSR markers are being used in breeding for
blast resistance. Bulked segregant analysis (BSA) is the simple method for tagging resistance ge~e by SSR markers. Quantitative
trait loci (QTLs) have also been mapped and· most of them are linked to qualitative genes. SSR markers linked to the gene are being
used to select plants possessing the desired trait and markers throughout the genome are being used to select plants that are
genetically similar to recurrent parent. Using SSR markers it may be possible to select blast resistance genotypes at any stage of crop
development from any small part of crop, to conduct many round of selection, to select without inoculums, without scoring, and
without testing in hot spot or artificial inoculation. Molecular based blast resistance breeding work is initiated focusing on resistance
gene tagging in Nepalese rice Iandraces and transferring resistance genes in cvs Jumli Marshi, K.humal-4 and Mansuli.