Effect of aluminum uptake on growth and enzyme activity in Pisum sativum var. ‘Alaska’ and ‘Little Marvel’

It is usually assumed that plant tissue responses to nutritional elements are due to specific genetic differences that may exist either between inbred or closely related species. Little Marvel (dwarf) and Alaska (normal) varieties of 14‐day old pea seedlings were treated with four different concentrations of Al‐containing nutrient solution (0.0mM, 0.2mM, 0.6mM and distilled H₂O), prior to being exposed for 14 days to either DARK, LIGHT, or UV. Selected tissues (root tip, main root, main stem and proximal stem) were bioassayed for peroxidase and polyphenol oxidase enzyme activities, fresh wt vs. dry wt, water uptake and stem growth. The present study suggests that Little Marvel and Alaska pea tissue responds to high toxicity levels of Al by demonstrating an enhancement of enzymic activity. Tissue weight, growth and water uptake also show differential tissue specificity in both Little Marvel and Alaska tissue, in terms of Al toxicity response, given a particular external exposure.     

提取方法对核桃青皮多酚提取效果的影响

为研究不同提取方法对核桃青皮多酚提取效果的影响,以乙醇为提取溶剂,分别采用溶剂提取法、微波辅助提取法、超声波辅助提取法、六偏磷酸钠（SHMP）辅助提取法提取核桃青皮多酚。研究结果表明：在试验条件下不同提取方法对核桃青皮的影响效果不同,其中SHMP辅助微波提取法效果最好,得率为4.01?mg/g,高于对照溶剂提取法的73.4%。因此,SHMP辅助微波提取方法是一种新型高效的核桃青皮多酚提取方法。     

Polyphenol oxidase activity and ortho‐diphenolic content in sunflower leaves in relation to boron nutrition.

Homogenates were prepared from the leaves of hydroponically cultivated sunflowers (Helianthus annuus, L.) under deficient, normal and toxic B conditions and the polyphenol oxidase activity together with the ortho‐diphenolic and micronutrient content was measured every week from one month to flowering.

B deficiency slightly depressed polyphenol oxidase activity and B toxicity decreased it significantly at all times, the response fitting a line versus the logarithm of the B concentration in solution. We found a positive correlation between polyphenol oxidase activity and the B content in leaves.

B action on enzymatic activity seemed not to be caused by direct interaction with substrates as the infiltration of B into deficient leaves did not restore the normal activity

According to our results we suggest that polyphenol oxidase activity may be a valid functional parameter to indicate the nutritional status of B in sunflower plants, if its specificity for B can be demonstrated.

The ortho‐diphenolic content did not change with the B levels used in our experiments. Neither did we find any correlation between enzymatic activity and the o‐diphenolic content of the leaves.     

高场强超声波对芒果多酚氧化酶和过氧化物酶钝化效果的研究

以芒果中多酚氧化酶(PPO)和过氧化物酶(POD)为研究对象,探讨加热与超声波作用对多酚氧化酶和过氧化物酶钝化效果的影响。结果表明:单独的加热(≤50℃)或0℃低温超声波(403.19、601.25、799.31 W/cm2)处理酶液,随着时间的延长,酶活性逐渐下降,但酶残留活性均在75%以上;而超声波与热处理结合能使POD和PPO显著失活,在45℃,799.31 W/cm2条件下处理15 min后,PPO、POD残余酶活力分别降至38.66%、14.43%。试验结果表明:超声波和热处理结合对芒果PPO和POD的钝化有协同效应。     

软儿梨冷冻贮藏过程酚类物质与多酚氧化酶的区域化分布

为研究冷冻贮藏中不同部位酚类物质和多酚氧化酶的分布特征,以青海省地方梨优良品种‘软儿梨’果实为研究材料,采用高效液相色谱法和比色法测定软儿梨果实后熟(室温)、冻藏(-18℃)和解冻(室温)3个时期的果皮、果肉中总多酚、绿原酸的含量和多酚氧化酶活性。结果表明:软儿梨果实后熟后,酚类物质果肉?果皮,多酚氧化酶则果皮?果肉;冷冻贮藏过程中,不同部位的酚类物质和多酚氧化酶均呈现不同程度的升高,但绿原酸在果皮急剧下降、果肉中略有增加。解冻后总体呈下降趋势,2个部位总酚、多酚氧化酶下降明显,而果皮中的绿原酸变化不大。研究表明:软儿梨果实后熟后,酚类物质和多酚氧化酶分布呈现区域化,冷冻贮藏加剧了酚类物质和多酚氧化酶活性的积累,导致了软儿梨冷冻贮藏后果皮先于果肉发生了褐变。     

酶促褐变对贮藏期间蓝莓汁品质的影响

采用热烫的方法,研究贮藏期间多酚氧化酶（PPO）活性对主要蓝莓汁品质的影响。贮藏期间果汁中的总糖、总酸、总酚含量均有所降低,褐变度随贮藏时间的延长而增大。 PPO活性与总酚含量、褐变度显著相关。     

多酚、黄酮及甾醇与番茄抗晚疫病关系

以对番茄晚疫病抗性较强的番茄品种‘25-1’和易感染番茄晚疫病的品种‘京乐502’为试材,通过人工接种病原的方法,研究多酚、黄酮及甾醇与番茄品种晚疫病抗性之间的关系。结果表明：（1）健康叶多酚类和甾醇类含量在2 个品种间无显著差异;黄酮类含量抗病品种‘25-1’显著高于感病品种‘京乐502’。（2）接种后,多酚类和黄酮类含量在2 个品种中均呈先增后减的趋势。峰值出现时间‘京乐502’晚于‘25-1’。总甾醇含量与番茄晚疫病抗性密切相关。接种晚疫病病原后,2 个品种中总甾醇含量均都呈下降趋势。随着病情的发展,感病品种‘京乐502’的总甾醇含量迅速下降,抗病品种‘25-1’下降较为缓慢。     

无核白葡萄多酚氧化酶基因的克隆与序列分析

为获得无核白葡萄中多酚氧化酶(PPO)的基因序列,以无核白葡萄果实为试材,进行基因同源克隆,得到多酚氧化酶基因CDS全长序列,其完整的编码框为1 824 bp,编码607个氨基酸(GenBank登陆号为KP271928);系统进化分析可知,其与葡萄科植物PPO基因同源性最高;生物信息学方法发现该蛋白分子量为67 392.44 Da,等电点为6.42,具典型的酪氨酸家族结构域,无信号肽结构,但有一个跨膜结构域,为亲水性蛋白;二级结构预测发现,PPO具有CuA与CuB两个结合区,分别嵌入蛋白活性腔中。该研究为进一步从分子水平探讨多酚氧化酶与褐变的关系奠定理论基础。     

北青龙衣褐变机制的研究

北青龙衣在由鲜品到干品的贮藏期间会出现失水、颜色变深等褐变现象。研究该褐变过程发生的机制,为控制褐变、提高药材的稳定性提供试验依据。采用北青龙衣鲜果果皮,4℃低温贮藏,研究其褐变度(browning degree,BD)、多酚氧化酶(polyphenol oxidase,PPO)、苯丙氨酸解氨酶(phenylalanine ammonialyase,PAL)、过氧化物酶(peroxidase,POD)活性变化、丙二醛(malondialdehyde,MDA)、总多酚(total polyphenols,TP)、还原糖含量及维生素C(Vitamin C,VC)含量变化。试验数据显示果皮颜色变深、TP含量下降、PPO活性降低、PAL活性上升、SOD和POD活性先上升后下降、MDA含量升高、还原糖和VC含量下降。BD与PPO、SOD、POD活性和TP含量呈显著负相关,与PAL活性呈显著正相关,与VC和还原糖无显著相关性。北青龙衣贮藏过程中发生了酶促褐变和非酶褐变,且以酶促褐变为主,PPO在酶促褐变中可能起主要作用。     

热浸法提取花生壳中多酚类物质的工艺研究

研究了热浸法提取花生壳中多酚类物质的工艺,对影响多酚得率的因素进行了单因素试验,通过正交试验确定最佳工艺条件为:乙醇体积分数为65%,浸提温度为75℃,料液比为1∶30,浸提时间为5h,此条件下多酚类物质的提取率为5.66mg/g。