The Initial Screening Of Mutants And The Research Of Transporter Related To C4Photosynthesis In Setaria Viridis

C4plants have certain advantages than C3plants in the anatomical structure,physiology and biochemistry as well as photorespiration, thus, the efficiency of C4photosynthesis is higher than that of C3photosynthesis to a certain extent. Therefore,engineering C4traits into C3rice has very important significance to increase riceyield and reduce global fertilizer utilization in theory.It is necessary to search a C4model plant in which the gene determining C4differentiation can be found finally. Corn, sorghum, etc. used as a model plant forresearching C4photosynthesis, but the size of them are too large. So it is difficult tocontrol the concentration of CO2in environment. Setaria viridis, a representative plantof C4NADP-malic enzyme subtype, has became a new model plant for C4photosynthesis with many good points: a relatively small genome of510Mb, shortstature, simple growth requirements, and rapid life cycle.In this study, forward genetics strategy contributes to research S. viridis whichStarts from the mutant phenotype to mutant gene waiting for being cloned and finallyfunction of the mutant gene can be defined. Seeds of S. viridis were induced withchemical mutagenesis and physical mutagenesis. Chemical method is0.1%,0.2%,0.3%,0.4%EMS for24h, and physical method is150Gy,200Gy,300Gy60Co γ-rays.Seed M1induced by EMS and radiated with60Co γ-rays.Gain the seeds of M1generation per plant and then sow a large scale of M2generation in experimental field.Currently, mutant library has been constructed and three categories of mutantion havebeen screened: Developmental mutants, Vein mutant, Morphological mutants. Thereare158EMS-induced morphological mutants with the mutant-induced frequency of2.6%48morphological mutants were screened in700M2radiated with60Co γ-raysand the mutation frequency was6.8%. Morphological mutation involves in tilling,leaf sheap and color, appearance of vein, Spike. Tilling mutants include a plant withno tilling grows endlong; Leaf sheap mutants include blade curled inward mutants, blade spiral mutants, blade nick mutants; leaf color mutants include blade chlorosismutants, blade reddening mutants; Vein morphological mutants include more majorveins mutants, the branch of major vein in the middle mutants, side veins mutants;Spike mutants inculde short spike mutants, curve spike mutants, spike bifurcationmutants, spike budding mutants.The list of13,662transcripts detected in either C.spinosa (C3)or C.gynandra(C4)tissues and the list of603transcripts that are differentially regulated between bothspecies. Some gene between the603transcripts changes in abundance similar to thecore C4genes, for example sodium-dependent pyruvate transporter (BASS2) thetranscript level of which was higher in C.gynandra than in C.spinosa. Therefore, thereis a surmise that BASS2is a tansporter related to C4photosynthesis. The localizationof BASS2in plastids was also evidenced by the green fluorescent protein (GFP)fluorescent image of a BASS2–GFP fusion protein, which was stably introduced intotransgenic tobacco plants. Arabidopsis thaliana bass2mutants lack pyruvate uptakeinto chloroplasts, which affects plastid-localized isopentenyl diphosphate synthesis, asevidenced by increased sensitivity of such mutants to mevastatin, an inhibitor ofcytosolic isopentenyl diphosphate biosynthesis. Therefore, there is a surmise thatBASS2plays a role in tansporting pyruvate which participates the synthesis ofterpenes in Arabidopsis thaliana. The purpose of this study is to identificate the roleof BASS2in S. viridis by RNAi.Three fragments of the gene were cloned and threeplant expression vectors were constructed. Multiple bud clumps belongs to S. viridiswere inducted used for transformation, and the transformants are beening screened.