Molecular Markers and Their Use in Marker‐Assisted Selection in Rice

Abstract

Increasing world population, shrinking cultivable rice (Oryza sativa L.) land area, water scarcity and excess, evolution of new biotypes of pests and diseases, and climate change pose serious challenges to rice breeders to increase production and productivity with multiple resistances to biotic and abiotic stresses. Recent advances in rice genomics research and completion of the rice genome sequence have made it possible to identify and map precisely a number of genes through linkage to DNA markers. Noteworthy examples of some of the genes tightly linked to markers are resistance to or tolerance of blast, bacterial blight, virus diseases, brown planthopper (Nilaparvata lugens), drought, submergence, salinity, and low temperature and improved agronomic and grain quality traits. Marker‐assisted selection (MAS) can be used for monitoring the presence or absence of these genes in breeding populations and can be combined with conventional breeding approaches. Marker‐assisted backcross breeding has been used to effectively integrate major genes or quantitative trait loci with large effect into widely grown varieties. Pyramiding different resistance genes using MAS provides opportunities to breeders to develop broad‐spectrum resistance for diseases and insects. The use of cost‐effective DNA markers derived from the fine mapped position of the genes for important agronomic traits and MAS strategies will provide opportunities for breeders to develop high‐yielding, stress‐resistant, and better‐quality rice cultivars.

Improvement of Salinity Stress Tolerance in Rice: Challenges and Opportunities

“…Moreover, salinity tolerance at the seedling and reproductive stages are only weakly, if at all, associated [84]. It has been reported that salinity tolerance at the seedling stage is independent of salinity tolerance at flowering/reproductive stage [85], for example, CN499-160-13-6 genotype has been confirmed as susceptible at seedling stage, but tolerant at the flowering stage [86]. Due to the variation in sensitivity to salinity during the life cycle, evaluation of salinity tolerance in rice is complex [87].…”

Genetic Improvement of Rice (Oryza sativa) For Salt Tolerance: A Review

“…The development of gene identification technologies using the tools of biotechnology provides ample opportunities for scientists to further improve modern cultivars (Jena and Mackill, 2008). Genomics tools and approaches, particularly the QTL mapping and comparative mapping offer new possibilities for crop improvement (Paterson, 2012;Saito et al, 2012).…”

Field level evaluation of rice introgression lines for heat tolerance and validation of markers linked to spikelet fertility

“…QTLs for heat tolerance were mapped on all chromosomes except chromosome 7 but fine mapping of these QTLs has not been reported. Identification of QTLs for heat tolerance may be limited by low marker coverage and small QTL effect (Steele et al 2006;Jena and Mackill 2008). Association mapping is another approach used for identifying genes controlling important traits (Borba et al 2010).…”