Improvement Of Grain Quality Trait Via Gene Editing Technology In Perennial Rice

The eating quality of rice is taking much more attention in recent years.Rice aroma characteristics and taste quality are important evaluation indicators of rice quality.The cultivation of fragrant rice and glutinous rice is an effective means to increase the additional value of rice and thus increase farmers’enthusiasm for rice production.Due to the absence of transgenic components and the high controllability of the target gene in the modified crops,genetic directional improvement using gene editing technology gradually shows its great potential application.With the identification of many genes with function in agronomic trait regulation and the development of related functional markers,marker-assisted selection has been widely used with increasingly prominent roles in crop breeding.However,fragrant rice breeding faces the bottleneck of a single genetic background source,which greatly restricts the development of fragrant rice Breeding process.The main way to solve this problem is to explore and utilize germplasm resources of fragrant rice and expand genetic diversity of fragrant rice.In this research,the molecular markers of the known rice aroma gene Badh2 were used to analyze817 rice germplasm resources and 25 wild rice ancestors’Badh2 genotypes.The rice with the aroma genotype（mutant Badh2）was analyzed by the taste method.Identification of aroma characteristics.The results showed that 83 copies of rice germplasm resources had mutant Badh2 genes,including 52 indica rice,30 japonica rice,and 1 intermediate type;while ordinary wild rice and Nivara wild rice were wild-type Badh2,indicating aroma The traits were artificially selected by natural mutation of the aroma gene Badh2 during domestication of cultivated rice.Eighty-three rice with mutant Badh2 were identified by artificial chewing method.The results showed that 28 rice had obvious aroma characteristics.It is speculated that the genetic background of Badh2 caused the accumulation of 2-acetyl-pyrroline in grains.The amounts were different.Among 28 fragrant rice materials,20 were indica rice,7 were japonica rice,and 1 was middle type,and the aroma intensity of indica rice was generally higher than that of japonica rice.The germplasm resources of fragrant rice identified in this study will provide important material support for genetic improvement of aroma characteristics of rice.With the rapid development of gene editing technology,it has gradually shown its application prospects by using gene editing technology to carry out directional improvement of crops.In this study,gene editing technology was used to edit the flavour gene Badh2 and amylose synthesis gene Wx of perennial rice（PR23 and Yunnan University 107）,so as to further improve the flavor characteristics of PR23 and reduce the amylose content of Yunnan University 107.In this study,CRISPR/Cas9gene editing vectors of Badh2 and Wx were constructed respectively,and pr23 and Yunnan University 107 were genetically transformed.21 PR23-Badh2-Cas transgenic lines（T₀ generation）and 23 Yunnan University 107-Wx-Cas9transgenic lines（T₀ generation）were obtained.According to molecular detection,6 of 21PR23-Badh2-Cas9 transgenic lines had different types of mutations.In addition,based on the analysis of aroma phenotype,four lines of rice produced different degrees of aroma.Among the 23 Yunnan University 07-Wx-Cas9 transgenic lines,8 have the mutation.Through the analysis of appearance characters of rice,it was found that the seeds of five lines were milky white,and it was speculated that the amylose content of the five lines decreased significantly.According to the results of this study,the Badh2 and Wx Genes of PR23 and Yunnan University 107 can be targeted to improve their flavour and amylose content and improve the quality of perennial rice.The results of this study can provide technical and material support for the further cultivation of high-quality perennial rice varieties and the improvement of its application potential.