Effect of calcium soil amendments on phenolic compounds and soft rot resistance in potato tubers

Nutrients such as boron, nitrogen and calcium stimulate the production of phenols. This research focuses on the role of calcium in increasing phenol metabolism in potato peels and the ensuing tuber resistance to soft rot pathogens was investigated. Two field experiments were conducted at the University of Zimbabwe campus plots in 2008 and 2009 summer seasons. Sprouted tubers of cv. BP1 were planted in plots treated with different fertilizer combinations. The treatments were: 1) compound S (7N: 21P: 8K) + ammonium nitrate (34 %N) 2) compound D (7N: 14P: 7K) + calcium nitrate (19 Ca: 15.5N) 3) compound S + calcium nitrate and 4) compound D + ammonium nitrate. The harvested progeny tubers were inoculated with Pectobacterium carotovorum subsp. brasiliense. Calcium amendment increased the activities of enzymes (phenylalanine ammonia-lyase, polyphenol oxidase and peroxidases) involved in the metabolism of phenolics and total soluble phenols. Calcium amendment significantly reduced (P < 0.05) the maceration effect of P. carotovorum subsp. brasiliense in tuber tissues. Chlorogenic acid, caffeic acid and calcium, but not ferulic acid content were significantly higher (P < 0.05) in plants grown in calcium treated plots. Calcium positively and significantly correlated with polyphenol oxidase (PPO), phenylalanine (PAL) and peroxidase (POD), while chlorogenic and caffeic acid showed a positive relationship with POD and PPO. Calcium amendment significantly reduced maceration symptom caused by the bacteria (P < 0.05), resulting in smaller decayed zone diameters on inoculated tubers from calcium-treated plots. This study shows that soil amendments of calcium increase concentration of calcium, caffeic and chlorogenic acid in tuber peels and also reduces maceration effect of pectinolytic pathogens. Reduced maceration could be due to increased levels of caffeic and chlorogenic acid which have antimicrobial properties.     

几丁质酶产生菌发酵液对水稻生长及防御酶活性的影响

用自然界筛选到的抗稻瘟病几丁质酶产生菌H3发酵液处理水稻幼苗后,检测水稻幼苗质量及其体内苯丙氨酸解氨酶(PAL)、过氧化氢酶(CAT)和过氧化物酶(POD)活性的变化,以期探讨发酵液的作用机理。结果表明,H3菌株产酶发酵液处理2种水稻幼苗后,培两优288苗高和百苗干物重分别比对照分别增加58.9%、35.4%,旱干127苗高和百苗干物重比对照分别增加66.8%、26.2%,苯丙氨酸解氨酶活性和过氧化物酶活性明显增加,过氧化氢酶活性下降。H3菌株发酵液能诱导水稻幼苗防御酶的活性变化,使其朝有利于水稻幼苗生长和抵抗病害的方向发展。     

Study of catechin,epicatechin and their enantiomers during the progression of witches' broom disease in Mexican lime (Citrus aurantifolia)

Witches'broom diseases of Mexican lime (WBDL) caused by ‘Candidatus Phytoplasma aurantifolia, is a big threat to lime production in Southern Iran. In this investigation, concentration of catechin, epicatechin and their enantiomers were monitored during WBDL progression for 6 months. In addition, the activities of peroxidase (POD), phenylalanine ammonia-lyase (PAL), chalcone synthase (CHS) as well as the content of malondialdehyde (MDA) were assayed. The results showed that after 30 days of inoculation, levels of catechin and epicatechin were considerably increased up to 390% and 290% respectively, but both of them significantly decreased after 150 days. These changes in the levels of catechin and epicatechin are in well agreement with the activities of PAL, CHS and POD as well as the level of MDA. Does WBDL influence on biosynthesis of enantiomers in lime? The analysis of catechin enantiomeric ratio of infected leaves demonstrated that after 30 days of inoculation, the ratio of (+)-catechin changed from 61:39 to 79:21 and then remained almost constant. Finally, the infection of lime by WBDL, not only induced the production of resistance enzymes (PAL and CHS) as well as catechin and epicatechin but also enhanced the accumulation of (+)-enantiomer.     

Harpins蛋白防治黄瓜霜霉病机理研究I黄瓜接种Harpins蛋白后PAL酶活性的变化

通过分析棚室黄瓜在喷施不同浓度的Harpins蛋白后,叶片中苯丙氨酸解氨酶(PAL)活性变化 的规律,探讨了Harpins蛋白防治黄瓜霜霉病的机理,研究结果表明:黄瓜在喷施Harpins蛋白后不同 时期PAL活性变化是不一样的,0．005g/L浓度的Harpins蛋白接种后,叶片中苯丙氨酸解氨酶(PAL) 活性变化的规律与空白对照无显著差异,0．015、0．045g/L浓度的Harpins蛋白接种后,叶片中苯丙氨 酸解氨酶(PAL)活性变化的规律与空白对照差异显著。黄瓜接种Harpins蛋白后PAL活性的变化,可 作为一种生化指标来作为Harpins蛋白防治黄瓜霜霉病的一个证据。     

枣果实中苯丙氨酸解氨酶基因的克隆及序列分析

为给从分子水平上揭示枣核发育的机理及培育无核枣优良品种提供理论基础,以"金丝小枣"幼果为试材,对枣果实中苯丙氨酸解氨酶(PAL)基因进行了克隆,并进行了生物信息学分析.用分子克隆方法首次从枣树中克隆了苯丙氨酸解氨酶基因部分.DNA序列,并命名为ZjPAL,ZjPAL长1954 by,编码559个氨基酸.通过核苷酸和氨基...     

柱花草苯丙氨酸解氨酶（SgPALs）对生物胁迫与非生物胁迫的响应

本研究以热研2号柱花草为材料,分析其苯丙氨酸解氨酶（PAL）活性、总酚含量、类黄酮含量、总抗氧化能力和SgPALs基因表达模式对生物胁迫（炭疽菌侵染）与非生物胁迫（干旱和盐胁迫）的响应。结果表明,在3种胁迫处理下,柱花草不同组织部位的PAL活性增加18.58%~123.56%,且叶片的总酚含量、类黄酮含量和总抗氧化能力分别增加65.11%~68.00%、51.00%~76.87%和83.00%~262.08%,差异显著。在干旱和盐胁迫处理下,根系的总酚含量、类黄酮含量和总抗氧化能力也显著提高43.77%~51.12%、45.46%~45.98%和60.45%~97.89%。随后对SgPALs的表达模式分析表明,除SgPAL4外,其他3个SgPALs受炭疽菌侵染诱导上调表达;在干旱胁迫下,根系中4个SgPALs均增强表达,但叶片中仅SgPAL1和SgPAL4上调表达;在盐胁迫下,根系中4个SgPALs也都上调表达,叶片中除SgPAL3下调表达外,其他3个SgPALs增强表达。综上所述,在遭受生物胁迫和非生物胁迫时,柱花草中的SgPALs基因表达及PAL酶活性升高,伴随着总酚与类黄酮含量的同步升高,表明其对环境胁迫的抗性升高。     

Postharvest responses of hydroponically grown lettuce varieties to nitrogen application rate

Limited information is available on the influence of preharvest N application rates on postharvest quality of different lettuce genotypes. Two green leafy lettuce(Multigreen 1 and Multigreen 3) and red leafy lettuce(Multired 4) were grown in gravel film technique and fertigated with five different N application rates: 60, 90, 120, 150 and 180 mg L~(–1). The 120 mg L~(–1) N application is commercially recommended for lettuce. After harvest, lettuce samples were packed in a bioriented poly propylene packaging(5% O_2 and 5% CO_2) and held at 5°C and 85% RH for 3, 6, 9 and 12 days. The genotypes, preharvest N application rates and storage time affected the leaf colour coordinates, phenolic acids(dicaffeoyltataric acid, caffeoyl tartaric acid, 3-caffeoylquinic acid and 3,4-dihydroxycinnamic acid) and browning enzyme activities(phenylalanine ammonia-lyase(PAL), polyphenol oxidase(PPO) and peroxidase(POD)). Lower rates of N application at preharvest stage showed higher weight loss with the storage time increasing in Multigreen 3. In Multigreen 1, colour coordinate b* value decreased remarkably with N application rates from 60 to 120 mg L~(–1) due to the onset of browning during storage. While in Multigreen 3 and N application higher than 60 mg L~(–1) influenced the decrease in b* value. Browning occurred due to the increased activity of PAL enzyme and the availability of the substrates caftaric, chlorogenic, caffeic acids, PPO activity and production of browning pigments due to the activity of POD. Higher, N application rates(120 mg L~(–1)) influenced the browning mechanism and showed brownish red leaves in Multired 4 during storage. Higher ascorbic acid concentration played a role in reducing the onset of browning in the fresh cuts leaves of Mulitired 4 and Multigreen 3 fertilized with lower preharvest lower N application rates(120 mg L~(–1)). Preharvest N application at 90 mg L~(–1) retained the colour, ascorbic acid content and the phenolic acid components and extended the shelf life of Multired 4 lettuce up to 6 days.     

Harpins蛋白防治黄瓜霜霉病机理研究 Ⅰ黄瓜接种Harpins蛋白后PAL酶活性的变化

通过分析棚室黄瓜在喷施不同浓度的Harpins蛋白后，叶片中苯丙氨酸解氨酶(PAL)活性变化的规律，探讨了Harpins蛋白防治黄瓜霜霉病的机理，研究结果表明：黄瓜在喷施Harpins蛋白后不同时期PAL活性变化是不一样的，0.005g/L浓度的Harpins蛋白接种后，叶片中苯丙氨酸解氨酶(PAL)活性变化的规律与空白对照无显著差异，0.015、0.045g/L浓度的Harpins蛋白接种后，叶片中苯丙氨酸解氨酶(PAL)活性变化的规律与空白对照差异显著。黄瓜接种Harpins蛋白后PAL活性的变化，可作为一种生化指标来作为Harpins蛋白防治黄瓜霜霉病的一个证据。     

甘蓝型油菜苯丙氨酸解氨酶的分离纯化与性质研究

分离和部分纯化了甘蓝型油菜荚果中的苯丙氨酸解氨酶,经SDS-聚丙烯酰胺凝胶电泳测得亚基分子量约为46KD,推测其全酶分子量为184KD。酶反应的最适pH值为8.4;最适温度是60℃,70℃处理10min残存活性仍保持在50%,具有较好的耐热性;底物L-Phe最适反应浓度是0.02mol/L;有两个Km值,即Km1为1.01×10-3mol/L,Km2为0.778×10-3mol/L。     

不同高粱基因型感蚜虫前后POD、PPO、PAL酶活性变化分析

对几个不同高粱基因型田间感蚜虫前后的三种酶POD、PPO、PAL活性进行了测定,结果表明,感蚜前后各材料POD活性都有明显的增加,抗蚜虫材料河农16前后均比其它几个材料的活性低;PPO活性感虫后有明显的增加,变化情况与POD类似;PAL活性感后有明显的增加,河农16与其它几个感蚜型相比,稳定性显著。表明POD、PPO与诱导抗性有关,而PAL在抗蚜材料河农16中为组成型表达的,可能受抗蚜虫基因的控制。