Production And Screening Of C4-like Anatomical Structural Materials In Rice

Most of dry matter of green plants come from photosynthesis.Compared with C3 photosynthesis crops,C4 photosynthesis crops have three major advantages:50-100% higher yield,double the water utilization rate and higher nitrogen utilization rate.Transforming C3 rice into C4 rice which have C4 cycle through synthetic biology and systems/integrated biology have the potential to greatly improve photosynthetic efficiency and thus yield.Compared with C3 photosynthesis,the most obvious characteristic of C4 photosynthesis is that the photosynthetic reaction occurs in the second-class cell system composed of mesophyll cells and vascular bundle sheath cells.Therefore,the prerequisite for constructing C4 rice is to establish leaves with C4-like anatomical structural in rice.Finding and identifying genes related to the formation of C4-like anatomical structures has important biological theory and production significance.Transcription factors can regulate plant development,induced defense and stress response through regulating genes expression at the transcriptional and post-transcriptional level.C4 plants evolved from C3 plants,and the transcription factors of C4 plants also changed accordingly which enable plants to produce physical spaces and environments suitable for C4 photosynthetic pathways by regulating the expression levels of target genes.The transcription factors related to the C4 photosynthetic pathway can be obtained by transcriptome analysis of C3 plants and C4 plants.These transcription factors are likely to participate in the establish of the C4 photosynthetic pathway.This thesis takes transcription factors as the research object,constructs transgenic rice by transferring maize transcription factors into rice.Screening transgenic plants with C4-like anatomical structure from transgenic rice and then select candidate genes to study their expression patterns and functions.This thesis attempts to find transcription factors related to the development of C4-like anatomical structures thus provides new ideas for the construction of C4 rice.The main results of this thesis are as follows:1: Analyze 500 maize transcription factors and divide them into 44 families including ARF,bHLH,GRAS,and MYB.Constructed 500 transgenic rice overexpression vectors of these maize transcription factors through the Gateway system.2: Agrobacterium-mediated method was used to transform the transformation vectors of maize transcription factors,and 330 maize transcription factors obtained transgenic plants finaly,accounting for 66% of the total.3: A group of transgenic rice with phenotypes was observed in the field,accounting for more than 22% of the total.76 transgenic rice lines with photosynthetic efficiency and stomatal conductance significantly different from Nipponbare were screened,accounting for 23% of the total.4: Screened a group of transgenic rice with altered leaf anatomical structure,and obtained a group of candidate maize transcription factors related to the formation of C4-like anatomical structure,such as ZmGRAS19;screened a group of transgenic rice with suspected chloroplasts in the vascular bundle sheath cells of the leaf,Obtained a group of candidate maize transcription factors that regulate chloroplast development,such as ZmGLK57.5: The rice homologous genes of the selected maize transcription factors were constructed for overexpression,CRISPR / Cas9 knockout and other related vectors,then transformed into rice.