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

Abstract

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.