甘蓝型油菜耐铝极端品种筛选及耐铝生理机制初步解析

Screening extreme varieties with aluminum tolerance and analyzing physiological mechanisms of aluminum tolerance in Brassica napus

为筛选不同铝敏感性油菜品种并探究油菜对铝毒的耐受机制,以997份甘蓝型油菜自然品种为材料,采用土培初筛和营养液复筛的两步筛选法,以地上部鲜质量和相对根系伸长率为指标筛选获得甘蓝型油菜不同铝敏感性品种,解析油菜耐铝的生理机制。结果显示,997份甘蓝型油菜自然品种苗期在酸性土壤上表现出显著的基因型差异,从中筛选出142个不同铝敏感性极端品种,含77份铝耐受品种和65份铝敏感品种;进一步利用营养液培养体系在加铝和不加铝处理下对142个油菜品种进行复筛,通过聚类分析发现,97个品种在2个培养体系中具有较好的生长一致性;经过多次表型重复试验最终确定2个铝耐受品种(806和985)和2个铝敏感品种(482和811)。在铝毒处理下铝敏感品种(482和811)生物量相比不加铝处理下降约45%,根系生长显著被抑制,而铝耐受品种则无明显差异。进一步分析发现,相比铝敏感品种,铝耐受品种在铝毒条件下根系中积累的铝更少,活性氧含量更低,且根系中抗氧化酶(CAT和POD)的活性相比无铝处理显著增加,这可能是油菜耐铝的重要生理机制之一。

997 natural Brassica napus varieties were used to screen rapeseed varieties sensitive to aluminum(Al)and study the tolerance mechanism of rapeseed to Al toxicity.The two-step screening method of soil culture initial screening and nutrient solution culture re-screening was conducted.The aboveground fresh mass and relative root elongation were used as indicators to screen Brassica napus varieties sensitive to aluminum.The physiological mechanism of aluminum tolerance in rapeseed was analyzed.The results showed that 997 natural Brassica napus varieties had significant genotypic differences at the stage of seedling in acidic soil.142 extreme varieties with different aluminum sensitivity including 77 varieties tolerant to aluminum and 65 varieties sensitive to aluminum were screened.A nutrient solution culture system was used to re-screen the 142 rapeseed varieties under aluminum and no aluminum.The results of cluster analysis showed that 97 varieties exhibited good consistency of growth in two cultivation systems.Two aluminum varieties(806 and 985)tolerant to aluminum and two varieties(482 and 811)sensitive to aluminum were finally determined after multiple repeated phenotypic experiments.The biomass of varieties(482 and 811)sensitive to aluminum under aluminum toxicity decreased by about 45%compared to that under nonaluminum treatment,and root growth was significantly inhibited,while varieties tolerant to aluminum had no significant difference.Compared to varieties sensitive to aluminum,varieties tolerant to aluminum accumulated less aluminum in their roots under aluminum toxicity,had lower levels of reactive oxygen species,and significantly increased the activity of antioxidant enzymes including CAT and POD in their roots compared to that under no aluminum,indicating that it may be one of the important physiological mechanisms of aluminum tolerance in rapeseed.