施氮量和株高采收时期对油蔬两用型油菜菜薹糖分积累的影响

Effects of Nitrogen Rates and Plant Heights During Harvesting on Carbohydrate Accumulation in Young Stem of Oil-Vegetable Double Usage Type Rapeseed

为明确氮肥用量和采收株高影响油蔬两用型油菜品种菜薹糖分积累的机制,以富硒1号油菜品系为材料,采用裂区试验设计,研究了3个氮肥水平(120、180和240 kg·hm^(-2))和4个采收株高(20、30、40和50 cm)对菜薹糖组分含量的影响,比较了菜薹中蔗糖代谢关键酶转化酶(INV)、蔗糖合成酶(SS)和磷酸蔗糖合成酶(SPS)活性的变化,并对糖代谢关键酶活性基因的表达量进行了分析。结果表明,淀粉含量随着施氮量的增加而降低,其他糖分含量在施氮量为180 kg·hm^(-2)时显著高于其他施氮处理,表明过高和过低施氮量均不利于菜薹糖分积累。就不同采收株高而言,菜薹中果糖、淀粉、葡萄糖和蔗糖含量在株高20 cm采收时最高;海藻糖和山梨醇含量在株高40 cm采收时显著高于其他处理。菜薹SPS活性在各施氮量和采收株高处理下均比INV和SS活性低,表明菜薹中蔗糖以分解成小分子单糖如葡萄糖、果糖等代谢活动为主。在菜薹各采收时期和施氮量处理下,蔗糖分解体系的蔗糖合成酶SUS1/SUS4、SUS3和转化酶A/N-INVA、CINV1、CINV2等基因表达模式互补且为上调,增强了蔗糖的分解,而对蔗糖磷酸合成酶SPS1/SPS2的表达量影响很小。本研究结果为油蔬两用型油菜薹品种合理氮肥运筹提供了理论依据。

In order to uncover mechanism of the effect of nitrogen rates and harvesting plant heights on the carbohydrate accumulation in young stem of oil-vegetable dual usage type of rapeseed(Brassica napus L.),a field experiment,using split plot design,was conducted to assay the contents of carbohydrate profile,to compare the activities of key enzymes for sucrose metabolism including invertase(INV),sucrose synthase(SS),and sucrose phosphate synthase(SPS),and to dissect the transcript amounts of key genes using Fuxi 1 as plant material.Three nitrogen rates including 120,180,and 240 kg·hm^(-2)was served as main plot while four harvesting plant heights including 20,30,40,and 50 cm was served as sub-main plot.Result showed that all carbohydrate contents in young stem of rapeseed at the nitrogen rate of 180 kg·hm^(-2)were significantly higher than other treatments except that starch content decreased as nitrogen rates increased.The result indicated that excessive or deficiency in nitrogen application was not benefit for the carbohydrate accumulation in young stem of rapeseed.For the harvesting plant height treatment,fructose,starch,glucose,and sucrose content at 20 cm of plant height was higher than other plant heights in young stem of rapeseed.However,trehalose and sorbierite achieved the highest content at 40 cm of harvesting plant height in young stem of rapeseed.SPS activity was lower than those of INV and SS under different nitrogen rates and harvesting plant heights,indicating that the cleavage of sucrose into small molecules such as glucose and fructose was the main metabolic process in young stem of rapeseed.The complementary of up-regulation mode of sucrose cleavage genes both on sucrose synthase such as SUS1/SUS4 and SUS3,and invetase such as A/N-INVA,CINV1 and CINV2 enhanced the degradation of sucrose under different nitrogen rates and harvesting plant heights.However,few influences on the SPS1/SPS2 expression were found at different harvesting plant heights.The study provides the evidences for appropriate nitrogen application in oil-vegetable duel usage type of rapeseed.