氮磷亏缺条件下杨树幼苗根系分泌酚酸的动态

摘要

采用循环收集装置收集杨树幼苗根系分泌物,采用超高压液相色谱法( UPLC)对根系分泌物中的酚酸含量进行测定.结果表明:在正常、缺N、缺P处理下杨树幼苗根系均能分泌对羟基苯甲酸、香草醛、苯甲酸和肉桂酸等酚酸类物质,养分缺乏显著促进杨树根系分泌酚酸.在缺N条件下,杨树幼苗较正常培养条件下酚酸分泌增加量为对羟基苯甲酸125％～263％、香草醛201％ ～316％、苯甲酸230％～332％、肉桂酸138％～188％,且根系分泌的各酚酸量随着胁迫时间的延长呈明显增加趋势,但3个培养时间段内(0～5天,6～10天,11 ～15天)酚酸分泌量差异未达显著水平(P＞0.05)；在缺P条件下,杨树幼苗较正常培养条件下酚酸分泌增加量为:对羟基苯甲酸96％～124％、香草醛58％～156％、苯甲酸222％～734％、肉桂酸99％ ～ 328％,其中,苯甲酸和香草醛的分泌量随胁迫时间的延长呈明显增加趋势,而苯甲酸和肉桂酸呈现先升后降的趋势.缺N、缺P处理下,杨树幼苗根系分泌酚酸的平均速率也存在一定差异,对羟基苯甲酸和香草醛在缺N条件下的平均分泌速率高于缺P培养,而苯甲酸和肉桂酸的平均分泌速率低于缺P培养.杨树幼苗在N,P缺乏条件下根系分泌酚酸的动态规律在一定程度上反映了逆境对植物分泌酚酸的影响.%A cycling collection device was used to collect root exudates of poplar 1-107 (Populus × euramericana ' Neva' ) seedlings grown under N or P deficiency conditions. The ultrahigh performance liquid chromatography (UPLC) was used to assay the amount of phenolic acids in the root exudates, to study the secretion dynamics of several phenolic acids. The results showed that some phenolic acids, ie. P-hydrobenzoic, vanillin, benzoic acid and cinnamic acid, were able to be secreted from roots of the seedlings grown under normal and nutrient deficiency conditions. However, nutrient deficiency could significantly promote the secretion of phenolic acids from the roots. Under nitrogen-deficient conditions, the amount of p-hydrobenzoic acid was 125% -263% , vanillin 201% -316% , benzoic acid 230% -332% , cinnamic acid 138% -188% of that in normal conditions, respectively. The secretion amount of phenolic acids increased with the stress duration. But, there was no significant difference among three culturing periods (0-5 d, 6-10 d, 11 -15 d). Under phosphorus-deficient conditions, the secretion amount of p-hydrobenzoic acid increased by 96% - 124% , vanillin 58% - 156% , benzoic acid 222% - 734% , cinnamic acid 99% - 328% in comparison with the normal conditions. Furthermore, the amount of benzoic acid and vanillin all increased with treatment duration under phosphorus deficiency conditions, while the amount of benzoic acid and cinnamic acid appeared increasing initially and then decreasing with treating time. Additionally, the average secretion rate of phenolic acids was significantly different between nitrogen and phosphorus deficiency conditions. The secretion rate of p-hydrobenzoic acid and vanillin under nitrogen-deficient conditions was faster than phosphorus-deficient conditions, while the secretion rate of benzoic acid and cinnamic acid was slower than phosphorus-deficient conditions. The secretion dynamics of phenolic acids reflected the effects of stress environments on the secretion of poplar roots, and shedlight on the mechanism of their accumulation in the rhizosphere soil.