过量表达Fa14-3-3C促进拟南芥对低氮胁迫耐受性的研究

Enhanced tolerance of Arabidopsis over expressing Fa14-3-3C from tall fescue(Festuca arundinacea)to low-nitrogen stress

氮元素是植物生长发育过程必不可少的营养元素之一,对禾本科作物生长的影响更加明显。本研究采用RACE技术从高羊茅叶片中克隆获得Fa14-3-3C基因全长,并对其亚细胞定位与分子功能进行系统研究。在烟草表皮细胞中观察发现Fa14-3-3C-GFP主要定位在细胞质中与细胞膜上。将Fa14-3-3C基因在拟南芥中过量表达获得3个单拷贝转基因株系(抗性分离比为3∶1)。在低氮胁迫反应中,Fa14-3-3C过量表达株系OE-1与OE-3的根鲜重显著比野生型高,而OE-2与野生型差异不显著,通过荧光定量PCR分析发现OE-1与OE-3过量表达明显而OE-2没有过量表达,说明Fa14-3-3C对植物耐低氮胁迫调节具有剂量效应。定量观察植物根系生长发现在低氮处理早期OE-1转基因株系就显著优于野生型,主要是通过补偿根系生长的方式缓解低氮胁迫对植物的伤害。因此本研究不仅获得了耐低氮胁迫候选基因,而且验证了其在模式植物中的分子功能,为进一步通过基因工程等手段培育耐低氮胁迫种质资源奠定基础,具有重要理论研究价值与生产应用前景。

Ni trogen is essent ial for the growth and development of plants, especially gramineous crop plants. In this study, the full-length Fal4-3-3C gene was obtained by rapid amplification of cDNA ends from leaves of tall fescue （Festuca arundinacea ） . S u b c e l lu la r localization an aly se s sh ow ed th a t F a l4 - 3 - 3 C -GF P was main ly located in the cytoplasm and cell membrane when it was transiently expressed in tobacco epidermal cells. F a l i - 3-3C was transferred into Arabidopsis and th re e sin g le-co p y T -D N A in s e r t io n s tra in s sh owin g a 3 ： 1 h y g ro - mycin resistance segregation ratio were obtained. When wild-type and Fal4-3-3C overexpression strains were subjected to nitrogen deficiency, the root fresh weight was higher in strains OE-1 and OE-3 （but not OE-2） than in wild type. Quantitative real-time PCR analyses showed that Fal4-3-3C was highly expressed in OE-1 and OE-3, but not in OE-2, reflecting a dosage effect on the response to nitrogen deficiency. Dynamic analyses of the root growth of wild-type and Fal4-3-3C overexpression strains in nitrogen-deficient medium revealedthat OE -1 showed a dramat ic advantage over wi ld- type plants at the early stage of ni t rogen deficiency. This was mainly due to compensation growth to alleviate the negative effects of low-nitrogen stress in the OE -1 s tra in . Therefore, we have cloned a candidate gene conferring resistance to low-nitrogen stress, and verified its molec-ular function in the model plant Arabidopsis. T h e s e re su l ts are fu n d am e n ta l ly im p o r ta n t fo r b re ed in g crop plants resistant to low-nitrogen stress via genetic engineering.