Study Of Flowering Promoting Effect Of Early-Maturing Soybean's Cotyledons

Soybean is a typical short day plant.Different soybean cultivars have obvious different photoperiodic response.However,the flowering mechanism of early-marturing soybean in high latitude area isn't clear.Our study selected two cultivars,early-maturing soybean cultivar Heihe 27(HH27,photoperiod insensitive)and late-maturing soybean cultivar Zigongdongdou(ZGDD,photoperiod sensitive).We did systematic study of flowering promoting effect of early-marturing soybean's cotyledons by using grafting,photoperiod treatment and gene expression analysis.Main results were as follows:1.In RCG plant ZGDD/HH27(scion/stock),scion flowered in LD.In RG plant ZGDD/HH27(scion/stock),scion didn't flower in LD.In CG plant ZGDD/HH27/ZGDD(scion/stock/scion),scion flowered in LD.In RCG plant ZGDD/HH27 and CG plant ZGDD/HH27/ZGDD,scion produced many kinds of raceme morphology,including vegetative terminal,normal terminal and inflorescence reverse.These results demonstrated that early-maturing soybean's cotyledons could produce florigen.2.The relative expression level of GmFT2 a reduced gradually and loused circadian rhythm in ZGDD's cotyledons which were exposed to 0 h light.The relative expression level of GmFT2 a increased gradually and had circadian rhythm in ZGDD's cotyledons which were exposed to 10 h light(SD).The relative expression level of GmFT2 a was stable and maintained circadian rhythm in ZGDD's cotyledons which were exposed to 14 h light(LD).With treatment of 10 h light(SD)to stock ZGDD's cotyledons in RCG plant ZGDD/ZGDD(scion/stock),scion could flower in LD.These results demonstrated that late-maturing soybean's cotyledons had photoperiodism,and produced florigen in SD.3.In RCG plant ZGDD/HH27(scion/stock),the relative expression level of GmFT2 a in stock HH27's cotyledons were significantly higher than that of ZGDD/ZGDD.Making RCG between 35S:GmFT2a ZGDD(as stock)and wild type ZGDD(as scion),35S:GmFT2a ZGDD stock could induce wild type ZGDD flowering in LD.These results demonstrated that GmFT2 a was positively correlated with florigen.Florigen may be the product of GmFT2 a itself or its downstream genes.4.This study used improved stem-cutting method to harvest soybean exudates.Then,we used improved TRIzol method to extract RNA and protein in exudates.These methods provided important technologies to explore florigen in early-maturing soybean's cotyledons.