**Author details**

*Protecting Rice Grains in the Post-Genomic Era*

**3. Conclusions**

of more *R* genes may be necessary.

**Acknowledgements**

**Conflict of interest**

resistance (**Table 2**). Recently, a new class resistance gene *Ptr* just cloned encoded an atypical protein and conferred broad-spectrum disease resistance and will provide diverse selection for resistance improvement [47]. To breeding rice cultivars with durable blast resistance, stacking several resistance genes still was the most effective method. To stack resistance gene purposefully, spectrum of each resistance gene must be determined, and also, the identification of differential blast races/isolates that distinguished each resistance gene in different districts was

With identification in the rice blast field nursery or functional marker detecting of major *R* genes, the amount of blast resistance resources was identified and provides diverse selections for hybrid rice resistance breeding. However, the recent finding showed that *Pita* required *Ptr* to function revealed that part of single *R* gene may be not functional as we thought originally [47], and further function analysis

For conventional rice breeding, all blast *R* genes must be stacked into breeding lines to be effective, whereas hybrid rice can stack blast *R* genes into two parents. For hybrid rice breeding, blast resistance was only a part of index, and other agronomic traits also need to be considered. Lines of Chuang 5 S stacked *Pi9* and *Pi49* have been found obvious differences on plant height, spike length, spike number and stigma exertion rate with the receptor, even though the blast resistance has improved [41]. Hence, blast resistance breeding for hybrid rice was a synthetic work

that contained resistance innovation and excellent agronomic trait selection. In this chapter, it introduced the progress on identification of resistance resources and the utilization of blast resistance genes. Traditional cross technique, combined with MAS, has been used to transfer different major *R* genes into parent's lines to improve the resistance of hybrid rice and achieved remarkable results. Following the improvement of blast resistance of the authorized varieties, it gratefully contributed to decrease the damage of rice blast disease and played important

This work was supported by Hunan Provincial Science and Technology Department (CN) (2018NK1020), Hunan Academy of Agricultural Science and Technology Innovation Project (2018ZD01-7), Hunan Academy of Agricultural Science and Technology Innovation Project (2017JC03), and Hunan Provincial

function on protection of rice production safety in China.

Natural Science Fund Youth Fund (2018JJ3379).

The authors declared that there was no conflict of interest.

critical for ensuring the effectiveness of resistance gene stacking [48].

**30**

Junjie Xing\*, Huafeng Deng and Longping Yuan Hunan Hybrid Rice Research Center, Changsha, Hunan, China

\*Address all correspondence to: xingjunjie@hhrrc.ac.cn

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
