Molecular Breeding Strategy and Challenges Towards Improvement of Blast Disease Resistance in Rice Crop

Abstract

Rice is a staple and most important security food crop consumed by almost half of the world’s population. More rice production is needed due to the rapid population growth in the world. Rice blast caused by the fungus, Magnaporthe oryzae is one of the most destructive diseases of this crop in different part of the world. Breakdown of blast resistance is the major cause of yield instability in several rice growing areas. There is a need to develop strategies providing long-lasting disease resistance against a broad spectrum of pathogens, giving protection for a long time over a broad geographic area, promising for sustainable rice production in the future. So far, molecular breeding approaches involving DNA markers, such as QTL mapping, marker-aided selection, gene pyramiding, allele mining and genetic transformation have been used to develop new resistant rice cultivars. Such techniques now are used as a low-cost, high-throughput alternative to conventional methods allowing rapid introgression of disease resistance genes into susceptible varieties as well as the incorporation of multiple genes into individual lines for more durable blast resistance. The paper briefly reviewed the progress of studies on this aspect to provide the interest information for rice disease resistance breeding. This review includes examples of how advanced molecular method have been used in breeding programs for improving blast resistance. New information and knowledge gained from previous research on the recent strategy and challenges towards improvement of blast disease such as pyramiding disease resistance gene for creating new rice varieties with high resistance against multiple diseases will undoubtedly provide new insights into the rice disease control.

Genetic analysis and identification of SSR markers associated with rice blast disease in a BC₂F₁ backcross population

“…Backcrossed plants in our study deviated from epistasis and the independent model. However, Ashkani et al (2015) reported that a dominant epistatic interaction exists in PS2, using pathotype P5.0 with an F 3 population. This suggests the presence of two independent dominant genes that result in epistatic effects of multiple loci with major and minor resistance genes.…”

“…Four dominant genes at different loci were identified against the most virulent pathotype of M. oryzae Tanweer et al, 2015a). In addition, Ashkani et al (2015) reported an epistatic effect in a study including two different races of fungus. Extensive information about host resistance as well as the pathogen are essential to develop new rice varieties with long-lasting blast resistance and a broad range of resistance consisting of both qualitative and quantitative genes (Padmavathi et al, 2005).…”

4-Coumarate-CoA Ligase-Like Gene OsAAE3 Negatively Mediates the Rice Blast Resistance, Floret Development and Lignin Biosynthesis

“…Rice blast is caused by the ascomycetous fungus Magnaporthe oryzae , which is one of the most serious and devastating epiphytic diseases in rice production worldwide (Ashkani et al, 2015). Currently, more than 24 major R genes conferring resistance to M. oryzae have been identified in rice, including Pi-ta (Jia et al, 2016), Pi-k (Wu et al, 2014), and Pb1 (Inoue et al, 2013), and modulation of these R genes significantly maintains and improves the grain yield and quality in modern rice cultivars.…”

Association mapping of resistance to rice blast in upland field conditions

“…However, resistance breakdown following adaptation of the fungus has frequently been observed (Ou 1985) and breeding durably resistant rice cultivars remains a challenge. Molecular breeding approaches facilitate the identification and deployment of resistance genes (Ashkani et al 2015) and effective and durable resistance would be best achieved by combining both quantitative and qualitative resistance (Ballini et al 2008; Boyd et al 2013). …”