蓝莓根系响应铝胁迫的生理途径分析

Cultivation areas of which have increased rapidly in China recently, because of the high economic values of blueberry. Blueberry plants are limited to acidic soils high in organic matter. Establishing blueberry on a mineral soil is successful when adding organic matter in the form of peat, however the amendments of peat may account for as much as 45% of planting costs. How to reduce the application of organic matter is becoming the bottleneck of blueberry industry. Aluminium (Al) toxicity is the major limiting factor of plant growth on acidic soils, recent works showed that blueberry was oxylophytes plant but sensitive to Al. Al ions may be binded by the addition of organic matter, which helped to reduce Al toxic effect on blueberry growth. It is suggested that one of important prerequisites is the improvement of blueberry Al tolerance to reduce the application of organic matter . However, the physiology and molecular regulator mechanisms of blueberry under Al stress is still unclear. So two blueberry cultivars with an Al-resistant genotypes and an Al-sensitive genotype are chosen to study Al resistance mechanisms of blueberry from nutrient absorption, change on the components of cell wall, anti-oxidation capacity, Al-activated organic acid exudation. And SSH is used for identification of differentially expressed genes in blueberry roots to understand the molecular mechanisms underlying the differential response to Al-stress. Ultimately,it is combined the physiological approaches with molecular results to clarify the main physiology approaches and key genes for blueberries to tolerance to Al toxicity. It is hoped to elucidate Al tolerance mechanisms of blueberry through this project, which would be beneficial to cultural practices and future selection of blueberry cultivars adapted to acidic soils low in organic matter.

蓝莓经济价值高，国内种植面积急剧增加。蓝莓生长需富含有机质的酸性土壤，实际种植常施用大量泥炭等有机物满足其生长，有机物的施用占种植成本45%。如何减少有机物施用降低成本正成为蓝莓产业发展的限制因子。铝毒是酸性土壤上植物生长的主要限制因子，研究表明蓝莓喜酸但易受铝毒害，有机物的施用对蓝莓铝毒害缓解有重要作用，提高蓝莓耐铝性有助于减少有机物施用。但蓝莓耐受铝毒害的生理机制仍不明确，影响着蓝莓品种的改良。因此本项目以耐铝性差异大的两个蓝莓品种为材料开展对比实验，从根系养分吸收、细胞壁组份变化、抗氧化能力、根系分泌物等方面，系统的探索蓝莓耐铝毒生理途径；基于SSH技术研究蓝莓根系铝诱导的基因表达状况，从而了解蓝莓耐铝毒的分子途径。并结合生理和分子实验结果，明确蓝莓耐受铝毒的关键生理途径和关键基因。最终通过本项目阐明蓝莓耐受铝毒害的生理和分子机理，为其种质资源评价和遗传改良提供理论依据。

蓝莓经济价值高，国内种植面积急剧增加。蓝莓生长需富含有机质的酸性土壤，实际种植常施用大量泥炭等有机物满足其生长，有机物的施用占种植成本45%。如何减少有机物施用降低成本正成为蓝莓产业发展的限制因子。铝毒是酸性土壤上植物生长的主要限制因子，研究表明蓝莓喜酸但易受铝毒害，有机物的施用对蓝莓铝毒害缓解有重要作用，提高蓝莓耐铝性有助于减少有机物施用。但蓝莓耐受铝毒害的生理机制仍不明确，影响着蓝莓品种的改良。因此本项目以耐铝性差异大的两个蓝莓品种为材料开展对比实验，从根系养分吸收、细胞壁组份变化、抗氧化能力、根系分泌物等方面，系统的探索蓝莓耐铝毒生理途径；基于SSH 技术研究蓝莓根系铝诱导的基因表达状况，从而了解蓝莓耐铝毒的分子途径。.研究结果表明铝耐受品种在长期铝胁迫处理下生物量、养分吸收以及叶片净光合速率没有受到任何影响，而敏感品种则受到显著抑制；进一步研究表明耐受品种养分吸收不受影响是由于铝胁迫处理下根系活力没有下降，细胞膜脂结构未受破坏，同时根系形态结构发生变化，根直径变小，单位质量根系长度和比表面积增加。.两个蓝莓品种根系和茎干中铝含量无显著差别，但是敏感品种叶片中铝含量204 mg/kg显著高于耐受品种77 mg/kg，表明蓝莓铝敏感品种叶片易累积铝。铝在敏感品种叶片累积导致并没有提高叶内酚类、黄酮类以及花青素等抗氧化能力强的物质含量增加，而铝耐受品种叶片中酚类物质显著增加，表明铝耐受品种可通过降低叶片铝累积量以及提高叶片抗氧化能力，从而保护叶片不受铝毒害。.铝胁迫处理下，铝耐受品种筛选到差异表达基因126个，其中上调68个，下调58个，铝敏感品种根系筛选到差异表达基因468个，其中上调380个，下调88个。差异基因主要与细胞新陈代谢、跨膜运输以及逆境响应相关。.对比分析两个蓝莓品种铝胁迫下根系分泌物的结果表明，两个品种均未检测到有机酸等缓解铝毒害的根系分泌物，而蓝莓根系分子研究中也未发现与根系有机酸分泌的相关基因(Mate或ALMT1)表达存在差异。