| Rice is one of the main food crops in the world,and excellent rice quality is the key to the development of the modern rice industry.There are many factors that affect the quality of rice,which can be divided into genetic and environmental factors.Cytokinins are a type of plant hormones that play important roles in processes,such as cell division,growth and development,and stress response.Zhongzao 39 is an early indica rice variety with the advantages of high yield and high rice yield,but poor rice quality.In this paper,the effect of cytokinin on rice quality was preliminaryly investigated by application of exogenous cytokinin kinetin（KT）treatments at concentrations of 10-10,10-9,10-8,10-7,10-6,and 10-5M,using Zhongzao 39 as the experimental material.The specific research results are as follows:1.After treatment to Zhongzao 39 with different concentrations of exogenous kinetin,thousand grain weight and grain thickness were significantly increased compared to the control,while grain length and grain width were not significantly different.Further analysis indicated that exogenous cytokinin treatment mainly increased plumpness and thus increased the thousand grain weight of brown rice.2.The results of appearance quality after exogenous KT treatment to Zhongzao 39showed that compared with the control,the chalkiness degree and chalkness rate significantly decreased and were the lowest in the treatment with 10-8M concentration,while they increased in the treatment with 10-5M concentration.The scanning electron microscopy results showed that the starch granules under the 10-8M concentration treatment were tightly arranged and smooth,while the starch granules under the 10-5M concentration treatment were unevenly arranged and porous.3.The results of the milled rice quality after exogenous KT treatment to Zhongzao 39showed that the head rice grain decreased in each concentration of KT treatment compared to the control.4.The results of cooking and eating quality after exogenous KT treatment to Zhongzao39 showed that the elongation rate and gelatinous consistency of rice increased in all treatments compared to the control.The consistence viscosity and setback viscosity of rice viscosity decreased after KT treatment at high concentrations.5.Transcriptome analysis showed that the number of differential genes in 10-5M treatment was significantly higher than that in 10-8M treatment.Go and KEGG functional annotation analysis found that 4 pathways of differential genes in 10-8M treatment were significantly enriched,and 5 pathways of differential genes in 10-5M treatment were extremely significantly enriched.In the plant hormone signal transduction pathway,11 genes were up-regulated and 22 genes were down regulated in 10-5M treatment.The up regulation multiple of LOC＿Os02g34260 gene was the highest,LOC＿Os06g0255 gene has the highest down-regulation multiple.In the metabolic pathway of starch and sucrose,four genes were down regulated in 10-5M treatment,LOC＿Os05g14440 gene has the highest down-regulation multiple;7 genes were up-regulated and 19 genes were down regulated in 10-5M treatment LOC＿Os08g36910 gene has the highest up regulation,LOC＿Os05g14440 gene has the highest down-regulation multiple.The results of fluorescence quantitative PCR（q RT PCR）showed that the analysis results of transcriptome data were reliable. |
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