| In order to study the molecular mechanism of exogenous ethylene workingin promoting the sugercane yeild and sucrose, this experiment took the cloned ofthree members of ACC synthase genes family and the full length cDNA of ACCoxdiase gene as the probes, respectively, the aim is to proof-test the spatial andtemporal expressions of ACC synthese genes (Sc-ACS1, Sc-ACS2 and Sc-ACS3)and ACC oxdiase gene(GZ-ACO) in stalks of different varieties, and to test theeffect of ethephon treatment to genes expression and their correlations withethylene production and sucrose accumulation in sugarcane.The results as follows:1,Took the sugarcane stalks as materials,we extracted total RNA fromjuices,bagasse and the mixture of juices and bagasse with isothiocyanate methodand Trizol Reagent Kit method. The result was that we extracted 28S,18S and5S rRNA from juices and the mixture;,but only 5S rRNA from bagasse; Thetranscription level ofmRNA, which from the juices, can be stand for the mRNAtranscription level of the sugarcane stalks.The total RNA from juices withisothiocyanate method was better than Trizol Reagent Kit method in yeild and purity.2,At late growth stage of sugarcane, the ethylene emanation of bothsugarcane varities were higher than CK after treated with ethephon of 400mg·L-1concentrations at 3d .Then the highest level was observed at 7d after treatment.The ethylene emanation was still higher than that of CK,although it wasdecreased gradually in a month.Therein, the B1 variety and G17 variety wererespectively decreased to the level of CK at 21d and 28d after treatment.Theethephon treatments improved significantly the ethylene emanation inimmature-internodes,and the discrepancy level was prominent.3,At late growth stage of sugarcane, ethephon of 400mg·L-1 concentrationsimproved sucrose accumulation in both varieties,it showed asimmature-internodes＞maturing-internodes＞matured-internodes.while theeffects of increasing suger content with ethephon were varied in differentvarieties. The sucrose accumulation of B1 was higher than control in all theinternodes beginning at 14d after ethephon treatment,especially, significantlyhigher than in the control at both 28d and 56d after treatment. Compared withthe control, the effect of sucrose accumulation inthe variety GT17 was not soobvious at 28d after ethephon treatment, even it was inhibited. And it wasexpressed significantly higher than control at 56d in the immature-internodes.The extent of sucrose improvement were the highest in immature-internodes ofthe both varieties and reached prominent discrepancy.4,Northern blotting analysis in both varieties showed that the expressions of Sc-ACS1 and Sc-ACS2 were retained at a lower level,while Sc-ACS3 andGZ-ACO were retained at a higher level in the control Of both varieties at lategrowth stage of sugarcane. Therein,before sucrose accumulation saturation, theexpression of Sc-ACS1 as follows: mature-internodes＞maturing-internodes＞immatured-internodes;and after sucrose accumulation saturation,the expressionlevel was contrary, immature-internodes＞maturing-internodes＞matured-internodes. The expressions of Sc-ACS2,Sc-ACS3 and GZ-ACO wasimmature-internodes＞maturing-internodes＞matured-intemodes at the entirelate growth stage and the process of sucrose accumulation. The discrepancy ofexpressions of four genes expressions were in spatial,temporal and theabundance of expressions.At 14d after treatment,the test showed that theexpression of Sc-ACS1 in B1 was stronger than that in G17; but the expressionof Sc-ACS2 and GZ-ACO were adverse,which was stronger in G17 than that inB1.The ethephon of 400mg·L-1 concentrations handled valid improved theexpressions of four genes in three internodes,especially in the immatureinternodes and the effect was long-term. Among them, the three members ofSc-ACS genes expressed in immature internodes, the expressions level ofSc-ACS1 and Sc-ACS2 were still keep on high level at 14-30d and then returnedto normal level of control;and Sc-ACS3 was still retaining high level aftertreatment at 45d and then returned to normal level of control at 56d; GZ-ACOhave a little improvement at 7d and 14d and then returned to normal level ofcontrol.The influence of ethephon on the expressions of four genes in different internodes of varieties mainly reflected that there was difference up in timewhen the Sc-ACS, ,Sc-ACS3 and GZ-ACO reached the theirsleves highestexpression;the expression reached the peak level in B1 at 14d after treatment andstill keep on high level,but G17 reached higher level at 56d. The law of fourgenes expressions in stalks was accordant with the regulation of ethyleneemanation and accumulation of sucrose.
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