蔗糖合酶基因AtSUS3干涉后对拟南芥角果发育的影响

蔗糖合酶(SuSy)是植物蔗糖代谢关键酶之一,该研究利用反向遗传学手段,采用RNAi技术抑制拟南芥中AtSUS3基因的表达,测定纯系转基因植株的抽苔率,并对酶活性、糖含量等指标以及糖代谢相关基因的表达进行了检测,探讨SuSy在植物发育中的作用。结果显示:(1)转基因拟南芥的抽苔平均早于野生型植株2～3d,且优先3～4d完成抽苔。(2)开花后生长天数对角果蔗糖和葡萄糖含量有显著影响,而对果糖含量影响不显著;开花后5d时,野生型株系的葡萄糖含量显著高于转基因株系SUS3-2,至15d时,两种转基因株系葡萄糖含量均显著低于野生型株系。(3)开花后生长天数对SuSy、SPS、INV的活性均有显著影响,随开花时间延长,野生型株系SuSy活性显著低于转基因株系,而SPS和INV则相反。(4)AtSUS3基因沉默对其他糖代谢基因有不同程度的影响,开花后5d时,转基因植株的角果中AtCesA1、AtCesA7和AtCINV1的表达量较野生型都有所增加;开花后15d时,转基因植株的角果中AtCesA1、AtCesA7的表达量较野生型高,而AtCINV、AtCwINV的表达量比野生型低。研究表明,拟南芥AtSUS3基因沉默后,在正常生长条件下未造成植株发育异常,同时还可能通过同源家族中其他SuSy的表达水平增加,促进了该酶及糖代谢相关基因整体水平的增加,有助于角果成熟。

Sucrose Synthase Gene-AtSUS3 with RNA Interference Affects Siliques Maturation in Arabidopsis thaliana

Sucrose synthase is a key enzyme in sucrose metabolism.In this study,we investigated the function of SUS family in Arabidopsis by using reverse genetics method.AtSUS3 was silenced in mRNA level by RNA interference technology.Using pure transgenic lines,we observed plants bolting rate,analyzed SUS,SPS,INV and CesA activity,detected soluble carbohydrate content and tested expression pattern of glycometabolism genes.(1)Comparison to wild plant,transgenic lines promote early bolting on an average of 2~3 d and ahead of time to complete bolting about 3~4 d.(2)Growth days after flowering (DAF) have significant impact on sucrose and glucose contents,but the impact on the fructose content does not significantly.5 DAF,the glucose content of the wild-type and transgenic line SUS3-15 is significantly higher than that of transgenic line SUS3-2.15 DAF,the glucose content of the transgenic lines is significantly lower than wild-type.(3)The growth days after flowering have a significant impact on SuSy,SPS and INV activities.With time extending,SuSy activity in the wild-type is significantly lower than that in the transgenic lines,but the SPS and INV activities are opposite.(4)We also detected that interfering AtSUS3 has different degrees impact to mRNA expression pattern in other sucrolysis genes.In 5 DAF transgenic siliques,the expression of AtCesA1,AtCesA7 and AtCINV1 are higher than that in wild siliques.In 15 DAF transgenic siliques,the expression of AtCesA1 and AtCesA7 are also higher than that in wild siliques,but the expression of AtCINV and AtCwINV are lower than that in wild siliques.These results indicated that transgenic plants have not developed anormally in normal culture conditions after AtSUS3 with RNA interference.It might be promote whole SuS activity to improve by other homologue SuSy genes and sucrolysis genes expression lever increase.All these reasons might facilitate siliques maturation.