硼促进根过渡区质外体碱性化减轻豌豆根尖铝毒的机理

Both boron deficiency and Al toxicity are the major factors affecting the agricultural productivity in acid soil. It is well known that B application alleviates Al toxicity, however, there are still debates on whether Al accumulation in roots can be reduced by B supply. Our previous research shows that B promotes the alkalinization and reduces Al accumulation in root transition zone while increase Al in elongation zone, which is hypothesized to be related to the regulation of plasma membrane H+-ATPase by auxin polar transport through root transition zone. Taking advantages of modern techniques such as LCSM, NMT, RT-PCR, FIA etc, the relationship between apoplast alkalinization and roles of B in alleviating Al toxicity will be studied under different pH situations with the adoption of rapid alkalinization factors (RALF) peptide. Relation between apoplast alkalinization and H+-ATPase will be carried out with the treatments of FC and VA, the stimulator and inhibitor of H+-ATPase, while adopting the mutants of RALF and its acceptor (ralf1 and fer4). The regulation of auxin transport on H+-ATPase will be studied by inhibiting the transporters of auxin efflux/influx by NPA/CHPAA or using mutants of the transporters (aux 1-7, eir 1-4). Auxin distribution will be detected in lines of auxin reporter and sensor, PIN2:GFP, DR5rev:GFP, DR5rev:GFP/pin2, DII-VENUS. Brefeldin (BFA), the inhibitor of exocytosis, will be used to study the mechanism of B and Al in regulation of auxin polar transport in the gene expression of PIN2 and AUX1, PIN2 recycling and auxin sensing. The mutants of auxin binding protein (abp1 mutants abp1-5 and its acceptor (rop6-1) will be used to confirm roles of auxin polar transport and auxin perception in regulation of H+-ATPase and apoplast alkalinization of root transition zone. The aims of the research are to disclose the mechanism of B in promoting apoplast alkalinization and alleviating Al toxicity to roots, thus to provide the understanding of the agricultural practice of B fertilization in alleviating Al toxicity besides supplying B, therefore to promote the productivity in acid soils.

缺硼和铝毒均是影响酸性土农业生产的重要问题,普遍认为施硼可以缓解铝毒，然而硼是否减少根尖铝累积尚存争议。我们前期的研究表明硼显著促进过渡区质外体碱性化，降低过渡区却促进伸长区铝的累积，其机理可能与生长素在过渡区的极性运输对质子泵的调控有关。利用LCSM、NMT、RT-PCR、FIA等技术，设计不同 pH（缓冲）环境，引入快速碱化因子RALF,研究过渡区质外体碱性化与铝毒的关系；利用FC、VA、突变体ralf1和fer4，研究过渡区碱性化与质子泵的关系；采用阻断生长素极性运输，利用生长素敏感元DII-VERNUS等，研究生长素运输对不同根区质膜H+-ATPase的调控；并利用囊泡运输抑制剂BFA和生长素感受突变体，研究硼和铝是否通过作用于生长素运输载体表达和循环及生长素信号感受而调节生长素极性运输。旨在更深入揭示硼缓解铝毒的内在机理。对于指导南方酸性土施肥，减轻土壤铝毒，具有重要实践意义。

缺硼和铝毒均严重影响南方酸性土壤农业生产。硼肥的施用可以具有补充土壤微量元素硼的作用外，还具有缓解铝毒的作用，然而其机理不清楚。采用NMT/MIFE、CLSM等技术，结合拟南芥突变体生长素合成、运输突变体，设计不同pH和缓冲处理及NPA、VA/FC等药剂学实验，研究了硼促硼缓解铝毒与根过渡区碱性化的关系；硼促进根过渡区碱性化缓解铝毒与质膜H+-ATPase的关系；生长素极性运输对不同根区质膜PM-H+-ATPase的调控；硼铝调控生长素极性运输的机理。通过研究证实硼通过调控生长素的极性运输，调节不同根区质子泵活性，促进根过渡区质外体碱性化，减少过渡区铝的累积，缓解铝毒的机理。研究还发现硼缓解铝毒的作用可能存在具有其他新机制。研究对于指导南方酸性土壤施肥，减轻土壤铝毒，具有重要实践意义。.研究成果已在植物学经典权威期刊Plant Physiology(2018)、Frontiers in Plant Science（2017，2篇）、Journal of Nanobiotechnology（2019）等发表相关研究成果（含专利4项），在5个国际会议和5个国内学术会议以大会报告、口头报告、会议论文和墙报等形式广泛交流成果，引起了国内外学者广泛关注，根系生长与生长素极性运输和细胞壁果胶的研究在国内外形成了重要影响力，在接下来的1-3年预计发表有重要影响力的文章3-4篇。.通过研究培养硕士研究生5名（4名已经毕业），博士研究生2名（1名已经毕业）。为更好地完成研究任务，借助学校高水平大学建设契机，在项目执行期间开展了广泛的国际合作与交流，全职引进海外高层次人才3名，兼职海外高层次人才11名，其中协助一人获得国家特聘专家，另一人获得广东省珠江学者讲座教授，组建了国际膜生物学与环境研究中心和国际化团队。