Full Length Research Paper

Breeding elite japonica-type soft rice with high protein content through the introduction of the anti-Waxy gene

Jian-yue Li¹*, Shen-zhong Xu¹, Li-jun Yang^{1, 2}, Yong-guo Zhou¹, Shi-jing Fan¹and Wei Zhang¹

¹College of Life and Environment Science, Shanghai Normal University, Shanghai, 200234, P. R. China.

²Shanghai Institute of Health Sciences, Shanghai, 201318, P. R. China.

*Corresponding author. E-mail: lijianyue01@yahoo.com.cn. Tel.: +86 21 64323816; Fax: +86 21 64322142.

Accepted 28 November, 2008

Low amylose rice (<10%) that lies between glutinous and viscidity rice is called “soft rice”. There is an extremely significant negative correlation between amylose contents and protein contents in common rice grains. In an attempt to analyze whether the anti-Waxy gene could increase protein content while reducing amylose content in the rice grains, and develop good soft rice varieties with high protein content, an anti-Waxy gene was introduced into the high-yield japonica rice strain, Shangshida No. 2. The amylose contents in the T₁ grains were analyzed. The amylose content in the T₁ grains derived from the T₀ plant with two integrated copies of the anti-Waxy gene was only 6.8%, just belonging to the range of soft rice. The T₅ transgenic rice seeds were developed, in which amylose content and protein content were 4.3 and 11.2%, respectively, and the corresponding indexes in the wild type were 12.7 and 9.5%, respectively. In conclusion, it was verified that the anti-Waxy gene could increase protein contents while reducing amylose contents of the rice grains; a kind of elite japonica transgenic rice with low amylose content and high protein content was obtained through the introduction of an anti-Waxy gene. In addition, a new rationale and method for breeding marker-free soft rice by Agrobacterium tumefaciens-mediated co-transformation is presented.

Key words: Rice, soft rice, amylose content, protein content, anti-Waxy gene.