Marker-assisted breeding of the rice restorer line Wanhui 6725 for disease resistance, submergence tolerance and aromatic fragrance.

Yanchang Luo,Kar Hui Ong,Zhongchao Yin,Aifang Zhang,Zefu Li,Tingchen Ma,Jianbo Yang

doi:10.1186/s12284-016-0139-9

Abstract

BackgroundRice is a staple food crop in the world. With the increase in world population and economic development, farmers need to produce more rice in limited field. However, the rice production is frequently affected by biotic and abiotic stresses. The use of natural disease resistance and stress tolerance through genetic breeding is the most efficient and economical way to combat or acclimate to these stresses. In addition, rice with aromatic fragrance can significantly increase market value for its good grain quality. Mianhui 725 (MH725) is an elite restorer line that has been widely used to produce three-line hybrid rice in China. We previously introduced rice bacterial blight resistance genes Xa4 and Xa21 into MH725 and obtained an introgression rice line Wanhui 421 (WH421), which theoretically possesses 96.9% genetic background of MH725.ResultsHere we report the introduction and pyramiding of disease resistance genes Xa27 and Pi9, submergence tolerance gene Sub1A and aromatic fragrance gene badh2.1 in WH421 through backcrossing and marker-assisted selection. The newly developed introgression rice line was designated as Wanhui 6725 (WH6725), which theoretically possesses 95.0% genetic background of MH725. WH6725 and its hybrid rice conferred disease resistance to both blast and bacterial blight diseases and showed tolerance to submergence for over 14 days without significant loss of viability. Compared with non-aromatic rice MH725, WH6725 has strong aromatic fragrance. The major important agronomic traits and grain quality of WH6725 and its hybrid rice obtained in field trials were similar to those of MH725 and the control hybrid rice, indicating that WH6725 is as good as MH725 when it is used as a restorer line for three-line hybrid rice production.ConclusionWe have successfully developed a new restorer line WH6725 with disease resistance to rice blast and bacterial blight, tolerance to submergence and aromatic fragrance, which can be used to replace MH725 for hybrid rice production.

Highlights

Rice is a staple food crop in the world
The genotypes at the badh2.1, Pi9, Sub1A and Xa27 loci in the cross and backcross progeny were determined by molecular markers M265/M355, NBS2-1, RM23887 and M124, respectively (Table 1)
The genotypes of the Xa4 and Xa21 loci in the backcross progeny were determined by molecular markers RM224 and 21, respectively (Table 1)

Summary

Introduction

Rice is a staple food crop in the world. With the increase in world population and economic development, farmers need to produce more rice in limited field. The rice production is frequently affected by biotic and abiotic stresses. Rice (Oryza sativa L.) is a staple food crop feeding more than three billion people. The second leap was the development of hybrid rice (Yuan et al 1994). The rapid population growth and economic development have been posing a growing pressure on rice researchers and farmers for increasing rice production in limited rice field. The rice production is frequently affected by biotic stress, including various diseases caused by pests and pathogens, and abiotic stress, such as drought and flood due to the global warming and climate change

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Discussion

Conclusion