Lipid composition and post-wounding degradation in potato slices from cultivars differing in susceptibility to autolysis

Summary The effect of cutting on lipid content and degradation were compared in tubers of potato cultivars resistant (Acresta, Aminca, Eba) or susceptible (Kastor, Pana, Tasso) to autolysis. Susceptible cultivars showed greater degradation of lipids and phospholipids as well as higher activity of lipid acyl-hydrolase. No significant differences were detected in the activity of lipoxygenase in the tissues of the studied cultivars.     

Hypersensitive and enzyme responses in potato tuber tissue treated withVerticillium dahliae and arachidonic acid

Wound-healing tuber tissues from two potato cultivars, one resistant (cv. Reddale) and one susceptible (cv. Kennebec) to Verticillium wilt caused by the fungusVerticillium dahliae were treated with elicitor preparations of either an autoclaved mycelial extract of the fungus or with the fungal component arachidonic acid (AA). Wound-healing tissues were analyzed for hypersensitive cell browning (HCB) and alterations in lipoxygenase (LOX), polyphenoloxidase (PPO), and peroxidase (PER) activities, because all three enzymes are thought to be involved in the hypersensitive response and plant defense. Healing Reddale tissues that were treated with the elicitors exhibited a much more rapid and intense HCB than did the healing Kennebec tissues. By 96 h, Reddale tissues treated with either elicitor preparation appeared dark brown and necrotic. Treated Kennebec tissues appeared only slightly darker than the controls after 96 h. LOX, PPO and PER activities in treated Reddale tissues were significantly less than that found in the control after 48 h, and by 96 h PPO and PER activities were nearly zero. In contrast, LOX activity in AA-treated Kennebec disks was higher than in the control at 96 h, while the activities of PPO and PER had decreased to about 60% of the control at the same time period. Our results show that HCB is strongly correlated withV. dahliae and AA elicitor treatments in the resistant vs. the susceptible cultivar, while the overall role of the three enzymes in cell browning and death remain unclear.     

百香果贮藏过程中香气成分及其相关酶活性的变化特征

为阐明采后百香果香气品质的变化特征,本研究采用顶空-固相微萃取（HS-SPME）结合气相色谱-质谱联用技术（GC-MS）,研究了常温（25 ℃）、低温（6 ℃）贮藏期间百香果香气物质主要成分及其含量,酯类化合物代谢关键酶脂氧合酶（LOX）、醇酰基转移酶（AAT）、乙醇脱氢酶（ADH）和氢过氧化物裂解酶（HPL）活性的变化规律。结果表明：百香果在常温和低温贮藏期间,果汁中的香气物质均以酯类为主,相对含量分别占总香气物质的40.00%~60.32%和54.95%~69.27%,其次是醇类和酮类;进一步通过结构鉴定,在酯类物质中相对含量较高的化合物为丁酸乙酯、正己酸乙酯、丁酸己酯、乙酸乙酯、己酸己酯;常温下,百香果酯类物质相对含量在贮藏4 d时出现峰值（60.32%）、贮藏12 d时下降为40.00%,而低温下,其相对含量延至贮藏20 d时出现峰值（69.27%）,整个贮藏期内保持在54.62%~69.27%,表明低温贮藏可以维持酯类物质较高的相对含量。对百香果酯类代谢途径关键酶活性分析发现,果汁中LOX、AAT和HPL在低温贮藏前期（0~10 d）活性变化不大,贮藏后期表现活跃,最高值出现时间迟于常温贮藏,表明低温可以有效抑制酯类代谢关键酶活性;另外,酯类香气化合物相对含量与LOX、AAT、ADH、HPL活性具有较强相关性。本研究为百香果采后品质保持和保鲜技术提供了参考依据。     

Influence of post harvest temperature treatments,storage period and harvest date on development of spraing caused by tobacco rattle virus and potato mop-top virus

Summary The frequency of PMTV-spraing and TRV-spraing increased during storage in several cultivars. The only exception was cv. Saturna, where a decrease was observed in 1992. A spraing inducing treatment of one week at 18 °C followed by one week at 8 °C immediately after an early harvest increased the frequency and provided a rough estimate of the development of spraing in untreated tubers during storage. Under most circumstances wound healing at 25 °C compared with 15 °C resulted in a lower frequency of spraing during the storage period. The date of harvest had an important influence on development of spraing during storage and on the effect of post harvest temperature treatments. Therefore, physiological processes that induce or erase spraing are strongly related to tuber maturity. The mechanisms controlling development of symptoms seemingly are identical for the two spraing inducing vira.     

The Rate of Virus Spread in New Potato Cultivars in the North of Poland

The aim of this research was to assess the rate of increase in the level of tuber infection by PVY, PVM, and PLRV during three consecutive years of multiplication in the field for 17 new cultivars registered in Poland in 2009–2011 and for two cultivars not listed in the registry but popularly cultivated. The research was conducted in Bonin near Koszalin (north-western Poland) in 2010–2013. Tuber infection was assessed using DAS ELISA in a grow-out test in the winter-spring period. Among the 19 cultivars examined, eight had high resistance to PVY (above grade 8 on a scale of 1–9); during the 3-year research period, they were not infected. Also, cv. Gawin seemed more resistant than previously assumed. In contrast, cvs. Hermes and Sylvana, which were rated in the Netherlands as quite resistant, were clearly very susceptible (grade 3–4) in Polish conditions, as within 2 years 100% of tubers were infected with this virus. The greatest susceptibility to PVM was shown by cvs. Danuta and Stasia, 50% of which were infected, despite moderate exposure to the virus. Cultivars Zenia, Etiuda, Jubilat, and Viviana appeared very resistant to PVM as the number of infected tubers did not exceed 5%. PVM was not detected in the tubers of cvs. Bursztyn, Gustaw, and Legenda, which confirmed that these cultivars possess the Rm gene. Not all cultivars regarded susceptible (grade 3–4) to PLRV were infected. The virus was not found in tubers of cv. Bursztyn, while in cv. Hermes, assessed in the Netherlands as being quite resistant, almost 40% of tubers were infected.     

马铃薯不同品系贮藏期品质分析

马铃薯秋天入窖后,测定不同品系的还原糖含量、可溶性糖含量、淀粉含量,其结果为:还原糖含量入窖后到次年3月份逐渐升高,之后又快速下降,6-21还原糖含量最低,小白花还原糖含量最高;可溶性糖含量较稳定,只是不同品系表现趋势不同,6-21可溶性糖含量最低,1-38可溶性糖含量最高;淀粉含量也较稳定,6个品系总趋势为逐渐下降;1-38淀粉含量最高;大多数马铃薯品系的还原糖与可溶性糖呈正相关,可溶性糖与淀粉、还原糖与淀粉呈负相关。     

白叶1号的低温抗逆特性分析

比较了浙江省白化品种白叶1号返白阶段和主栽品种龙井43的低温抗性。结果表明,常温(25℃)环境下,返白期白叶1号反映光合能力的净光合速率Pn和最大羧化反应效率Vcmax都只有龙井43的70%~80%,而APX、POD等抗氧化酶活力比龙井43高30%以上。低温(2℃)处理24 h后,白叶1号反映光合能力的各项参数反而高于龙井43,同时其APX、POD、SOD活性也比龙井43分别高38.9%、33.3%、23.3%。说明白叶1号可能由于白化现象的产生,导致其抗氧化系统修复能力得到提高,因此在低温胁迫中,能够更为有效地清除叶片H2O2累积,缓解H2O2造成的氧化胁迫及光合抑制现象,具备比龙井43更好的低温耐受性。     

Compositional and enzymatic changes associated with the sugar-end defect in Russet Burbank potatoes

This study was initiated to determine the starchsugar composition and the activities of relevant enzymes of carbohydrate metabolism in Russet Burbank (cv.) potatoes exhibiting the sugar-end defect. The frequency of sugar-end tubers was increased by applying a single, transient, moisture-deficit stress period following tuberization. The following properties were unique to sugar-end tubers compared to normal tuber tissue. (1) Starch and total solids decreased markedly while glucose content increased 15-fold, (2) The concentration of Suc was markedly lower, (3) Pi was slightly but significantly increased, (4) The activities of UGPase and Susy decreased nearly 3 and 2-fold, respectively, (5) The activity of AGPase decreased 50%, (6) The ratio of STPLase to AGPase shifted over 3-fold in favor of starch mobilization, (7) Basal AcInv activity (assayed in the presence of inhibitor) increased 7-fold during storage, (8) Tuber Glc concentration showed a better correlation to basal Aclnv activity than to total Aclnv activity (inhibitor destroyed), (9) Kinetic analysis suggested that the level and/or effectiveness of the Aclnv inhibitor was decreased in the sugar-end tuber tissue. These results are discussed in relation to metabolic changes which occur in converting a starch storing tuber to one primarily involved with starch mobilization.     

1-MCP和乙烯利处理对采后菠萝蜜果实活性氧代谢的影响

以‘海大2号’菠萝蜜果实为材料,研究0.5 mg/L1-MCP(1-甲基环丙烯)和1 000 mg/L乙烯利处理对菠萝蜜果实活性氧代谢的影响,并探讨其与活性氧、活性氧清除酶和还原物质的关系,为菠萝蜜果实的保鲜提供理论依据。结果表明:随着菠萝蜜果实的成熟衰老,LOX(脂氧合酶)活性迅速增加,H2O2(过氧化氢)和MDA(丙二醛)含量快速积累,CAT(过氧化氢酶)和APX(抗坏血酸过氧化物酶)活性不断下降,SOD(超氧化物歧化酶)、POD(过氧化物酶)活性和GSH(谷胱甘肽)、还原型ASA(还原型抗坏血酸)含量均呈现先升后降的变化趋势。乙烯利处理极显著提高了LOX活性和降低了POD、APX和贮藏前期SOD活性,加快了贮藏中期H2O2和MDA含量的积累。1-MCP处理极显著降低了LOX活性和H2O2、MDA的含量,减少了活性氧产生,同时极显著提高了SOD、CAT活性和贮藏后期的POD、APX活性及GSH、还原型ASA含量,增强了活性氧清除能力。这些结果表明,乙烯利和1-MCP对菠萝蜜果实成熟衰老过程中活性氧的产生、保护酶活性及还原物质含量起重要调控作用。      

Ascorbate Oxidase levels in Wheat and their Relationship to Baking Quality

Flour samples from 127 samples of wheat of 13 different cultivars grown throughout New Zealand during two seasons were extracted with 1mNa₂SO₄(pH 8·3) and assayed for ascorbate oxidase (AOX) at pH 6·2 by a continuous spectrophotometric method. The mean AOX activity of the cultivar with the greatest activity, Domino, was more than three times that of the cultivar with the lowest activity, Brock. The differences in AOX activity amongst cultivars were maintained for two seasons. The range of AOX activities of different wheat samples within each cultivar was about two-fold for most cultivars. A sample of cv. Domino with the highest activity was 14 times more active than the lowest activity sample of cv. Brock. There was a significant correlation between low AOX activity and bake score of cultivars or individual wheat samples. There was also a correlation between log AOX and protein content, and protein content was also correlated with bake score. Flour stored for 300 days at 20°C and wheat stored for two or more years had reduced AOX activities and bake scores. However, flour containing low endogenous AOX activity produced the same bake scores with ascorbic acid plus squash AOX as with ascorbic acid alone. It was concluded that the level of AOX in wheat was not critical to the ascorbic acid improver effect, provided sufficient oxygen was mixed into the dough by high-speed mixers.     

Changes in sugar content and invertase activity in tubers of some Indian potato varieties stored at low temperature

Summary Significant differences were found in sugar content and invertase activity of tubers of 8 Indian cultivars stored at 3–5°C. Freshly harvested tubers of all the cultivars had low amounts of sugars, which increased during storage, and little or no basal invertase activity but both basal and total invertase activities in all the cultivars increased during storage. There were significant correlations between the reducing sugar content and basal and total invertase activities. Publication no. 116, Central Potato Research Institute, Shimla.     

Change in Some Glycoalkaloids of Potato under Different Storage Regimes

The potato (Solanum tuberosum L.) is an important food crop worldwide. Potato tubers can be stored to provide continuity of supply between production seasons, but it is important that they be stored under appropriate conditions as incorrect storage will result in deterioration in end user quality and may increase glycoalkaloid levels. We have investigated the effects of types of household storage on potato glycoalkaloid content (total glycoalkaloids [TGA]; α-solanine; α-chaconine) in Turkey. Tubers of potato cultivars (cvs.) Agria and Bettina were stored under four types of storage conditions (indirect sunlight for 10 h per day and dark storage for the remaining 14 h per day; storage under continuous fluorescent light; storage in constant darkness; storage in the dark in a refrigerator) for 56 days. Samples of tubers were taken at the beginning of the storage period and after 14, 28 and 56 days of storage for tuber glycoalkaloid measurement. Tubers stored in the three light environments showed an increase in glycoalkaloid levels; however, none of the cv. Agria tubers reached the critical level of 200 mg/kg tuber. On day 56 the TGA level of cv. Bettina tubers stored under fluorescent light reached 234.31 mg/kg.     

Influence of growth conditions on the value of crisphead lettuce

Crisphead lettuce (Lactuca sativa L. varcapitata cvs.Marius andSaladin) were grown with a nitrogen supply from 50 to 200 kg N/hectare. Heads were stored for one or two weeks at 1 °C in cold storage or ice bank cooling. Samples were taken for measurement of dry matter, sugars, vitamin C and nitrate. The content of dry matter, sugars (glucose, fructose) and vitamin C decreased with increasing level of nitrogen, and the content of nitrate increased. Except for nitrate the contents of the other quality attributes decreased at all nitrogen supply levels during storage. No differences were found between the storage systems, and beside fructose no significant differences were found between the two cultivars. The content of dry matter, vitamin C, and nitrate decreased from the outer to the inner head fraction, while the content of sugars increased. Trimming decreased the content of dry matter, vitamin C and nitrate and increased the content of sugars. To obtain heads from storage with a relatively high content of dry matter, sugars and vitamin C, and a relatively low content of nitrate the nitrogen supply must be as low as possible. Except for nitrate where no distinct results were found in this experiment it must also be recommended to store the heads as short time as possible. Possibly the cv.Saladin has some advantage quality attributes after storage compared with the cv.Marius.     

小麦籽粒成熟与萌发期间LOX的动态变化

为了解小麦籽粒中脂肪氧化酶(LOX)同工酶的代谢过程,选用4个小麦品种(鲁麦22、中优9507、内乡188、蒿优9409)为材料,采用薄层等电聚焦电泳(IEF)活性染色法检测和分析了小麦在籽粒成熟与种子萌发期间LOX同工酶酶谱的变化,并采用分光光度计法测定其活性.结果表明,在籽粒成熟期间,中优9507、内乡188、蒿优9409含有5条不同的同工酶条带,鲁麦22含有8条不同的LOX同工酶条带;随籽粒成熟度的增加,酸性和中性部分的LOX同工酶的合成与含量逐渐减少,碱性部分的LOX同工酶的合成与含量缓慢增加,说明成熟末期小麦籽粒主要积累碱性LOX;4个品种的LOX活性随籽粒成熟均呈现先逐渐降低至最低点后轻微反弹的变化趋势.在种子萌发期间,4个小麦品种都含有7条LOX同工酶条带,除萌发第一天外,随种子萌发的进行,酸性部分的LOX同工酶合成与含量减少,碱性和中性部分的LOX同工酶合成与含量缓慢增加,说明小麦种子在萌发过程中主要积累碱性LOX;4个品种的LOX活性均呈先保持一恒定高值后迅速下降至一恒定低值的变化趋势.无论是籽粒成熟期间还是种子萌发期间,影响小麦籽粒或种子中LOX酶活性大小的主要是酸性的LOX同工酶.     

水分胁迫对番木瓜糖代谢和膜脂过氧化的影响

以番木瓜(CaricapapayaL.)穗中红品种的5叶期小苗为试材,在水培条件下,研究了体积分数5%,7.5%,10%聚乙二醇(PEG)水分胁迫对番木瓜糖代谢和膜脂过氧化的影响。结果表明:随水分胁迫强度的增大,葡萄糖和果糖、相对电导率、饱和脂肪酸含量、乙烯释放率和脂氧合酶(LOX)活性均不同程度的提高,而叶片相对含水量、不饱和脂肪酸含量及脂肪酸不饱和指数则降低。相对电导率和LOX活性分别与干旱乙烯的生物合成有密切的关系。      

Changes in sugar,ash and minerals in four guava cultivars during ripening

Investigation of four guava cultivars showed that when the fruits were harvested at different stages of growth and development, total sugars increased slowly during the initial growing period followed by rapid increase during maturation and repining for all cultivars. The maximum level varied from 7.5 to 26.9%. Individual sugars: (fructose, glucose and sucrose) increased slowly during the initial growing period followed by rapid increase during maturation and ripening for all cultivars. The cultivars differed in their final sugar content; fructose varied from 5.6 to 7.7%, glucose from 1.9 to 18.1%, and sucrose from 6.2 to 7.8%. Total ash for all cultivars decreased slowly during the initial growing period followed by a sudden increase in the latter stage of maturation and ripening, with maximum level varying from 5.2 to 7.9%. Minerals: Ca, Mg, Na, K and P, for all cultivars decreased slowly during all stages of development. These results suggest that when guava fruits were picked 106–126 days after fruit set it ensures sufficient amount of total sugars and appreciable amount of minerals.     

In vitro tuberisation of potato: the interaction of ancymidol and photoperiod

Summary Ancymidol-induced in vitro tuberisation under different photoperiodic regimes (dark, SD=8 h, LD=16 h) and sucrose concentrations (2, 4, 6 and 8%) in cv. Jaerla (early) and cv. Baraka (late) was studied. Tuberisation was scored after 4 (dark) or 8 (light) weeks. Ancymidol significantly increased tuberisation under LD-SD for any sucrose concentration in both cultivars. Ancymidol also significantly increased tuberisation under LD-dark for 6% sucrose in both cultivars. Tuberisation in cv. Jaerla was significantly higher than in cv. Baraka for any photoperiodic treatment in the presence or absence of ancymidol with 4, 6 or 8% sucrose. The photoperiod SD-SD resulted in the higher level of tuberisation for any combination of sucrose, cultivar and ancymidol. The possible role of ancymidol is discussed.     

苯并噻二唑诱发水稻对稻瘟病抗性中防卫相关酶活性的变化

分析了苯并噻二唑（BTH）诱导水稻对稻瘟病抗性中苯丙氨酸解氨酶（PAL）、肉桂醇脱氢酶（CAD）、过氧化物酶（POD）、脂氧合酶（LOX）、β-1,3-葡聚糖酶和几丁酶等活性的变化。结果表明BTH诱导处理亲和性水稻品种第3叶后提高了处理叶及其上位第4叶中CAD、LOX和β-1,3-葡聚糖酶等的活性;经BTH处理的幼苗接种稻瘟菌后,处理叶和其上位叶中CAD、POD、LOX和β-1,3-葡聚糖酶等活性快速增加,且增长幅度均显著大于对照。几丁酶活性在受稻瘟菌侵染后升高,但BTH诱导处理并不能促进其增加;PAL活性在BTH处理及稻瘟菌接种后均无明显变化。这些结果说明,BTH处理能诱导CAD、POD、LOX和β-1,3-葡聚糖酶等活性的增加,而且这些酶活性的升高可能与BTH诱发系统获得抗性的表现有关。     

Effect and interaction of crop management factors on the glycoalkaloid concentration of potato tubers

Summary Potato tuber glycoalkaloid content was measured in response to nitrogen fertilizer rate, storage temperature, length of storage period and cultivar. Cvs Gemchip, Norchip and Russet Burbank were grown with applied nitrogen fertilizer rates of 0, 168 or 336 kg/ha and then stored at either 4.4 or 10°C. Total glycoalkaloid content was determined one month before harvest, at harvest, after three months of storage and after nine months of storage. Higher rates of nitrogen, higher storage temperature and a period of storage all resulted in significantly (P<0.05) higher concentration of glycoalkaloids. The cv Norchip had higher glycoalkaloids than cvs Gemchip or Russet Burbank. Only the storage period had more influence than the environment (difference between years). Significant (P<0.05) two-way interactions were detected for year x cultivar, year x nitrogen, storage period x cultivar and nitrogen x cultivar. Most interactions were due to the unique responses of cultivars.     

低温贮藏对琯溪蜜柚汁胞粒化与木质素代谢的影响

以琯溪蜜柚果实为材料,分别在1、4、7 ℃和室温下贮藏琯溪蜜柚果实,探讨贮藏温度对汁胞粒化、木质素含量以及汁胞木质素代谢相关酶活性的影响。结果表明：木质素合成相关酶的活性在整个贮藏过程中逐渐升高,汁胞粒化指数和木质素含量也均随着贮藏时间的延长而增高;在4、7 ℃下贮藏时,汁胞木质素含量、粒化指数以及木质素合成相关酶PAL、CAD、PPO和POD的活性均显著低于室温和1 ℃;在不同的贮藏温度下,琯溪蜜柚汁胞粒化程度与汁胞中木质素含量均呈正相关的关系。因此,1 ℃的低温不适宜琯溪蜜柚的贮藏,而4~7 ℃较适宜琯溪蜜柚的贮藏。