铝诱导甜高粱根尖胼胝质积累的调控途径研究

Aluminum (Al)-induced callose accumulation is one of Al toxicity mechanism in higher plants. Our previous study has found that over expression of SbGlu1 encodingβ-1,3-glucanase enhance the Al tolerance in arabidopsis by regulating the the decomposition of callose. The transitional difference of SbGlu1 between the Al tolerance and sensitive sweet sorghum can contribute to their variance in the sequence of promoter. Thus, present study included following contents (1) Investigating the upstream regulatory transcription factor and interacting protein of SbGLU1 by yeast one/ two hybrid library screening. (2)Functional analysis was performed on the transcription factor SbSTOP1, which putatively related closely to Al resistance in sweet sorghum. The regulatory downstream genes were selected by chromatin immune co precipitation and yeast two hybrid library selection. (3) Functional analysis was performed on the selected transcription factors or interactive genes by over-expression in the rice and rice art1 mutant. With above research, it is expected to elucidate the regulatory pathway of Al-induced callose accumulation mechanism in sweet sorghum.

铝胁迫下植物根尖胼胝质积累是重要的铝毒害机制。课题组前期研究发现，β-1,3-葡聚糖酶基因（SbGlu1）通过调控甜高粱胼胝质降解而提高其抗铝性，且耐铝和铝敏感品种SbGlu1的转录水平差异是由于启动子序列存在差异所致。因此，本研究欲通过（1）寻找SbGlu1的调控基因、蛋白；（2）克隆分析与抗铝性相关的转录因子SbSTOP1并寻找SbSTOP1的互作蛋白以及下游调控基因；（3）解析SbGLU1及SbSTOP1与互作因子之间的调控机制等3个方面的研究，以图进一步阐明Al诱导甜高粱根尖胼胝质积累的调控途径，为深入解析甜高粱抗铝及铝毒害机理提供科学支撑。

铝毒害是酸性土壤上限制农作物产量的主要因素。C2H2锌指转录因子STOP1可调控诸多Al响应基因，在植物耐Al过程中发挥关键作用。然而甜高粱STOP1的功能此前尚未报道。铝诱导植物根尖胼胝质积累不仅是Al毒害指标，亦是一种Al毒害机制。过量表达催化胼胝质降解的β-1,3-葡聚糖酶I（SbGlu1）可提高植物耐Al性，然而此酶在Al胁迫下的分子调控机制尚不清楚。. 项目首先从 SbSTOP1 向下，在研究SbSTOP1性质与功能的同时寻找其调控的下游基因；然后从 SbGlu1 向上，寻找调控 SbGlu1 的上游转录因子；最后解析Al 诱导甜高粱根尖胼胝质积累的调控途径。主要研究结果如下：. 1. 甜高粱中共发现四个SbSTOP1基因，其转录水平受Al诱导。. 2. 四个SbSTOP1蛋白定位于细胞核中，且具有转录活性。SbSTOP1d调控SbMATE、SbSTAR1 、SbSTAR2a及SbSTAR2b耐Al基因的转录。SbSTAR1 、SbSTAR2a及SbSTAR2b基因的转录水平受Al诱导，分别过量表达于拟南芥中，可提高转基因植物的耐Al性。. 3. SbSTOP1d与SbSTOP1b/SbSTOP1d具有相互作用，可能以同源二聚体或异源二聚体的方式发挥功能。. 4. SbSTOP1d异源表达于Atstop1可提高转基因植物的耐Al性。. 5. SbSTOP1对SbGlu1具有转录调控作用。. 6. 异源表达SbSTOP1可提高转基因株系中β-1,3-葡聚糖酶基因的转录水平，降低胼胝质含量，揭示一种新的耐Al调控途径，即SbSTOP1通过调节β-1,3-葡聚糖酶转录进而参与Al胁迫下胼胝质的降解。