Identification of organic acid-related genes and their expression profiles in two pear (Pyrus pyrifolia) cultivars with difference in predominant acid type at fruit ripening stage

‘Yandangxueli’ is a pear cultivar with predominant citric acid in the ripe fruit, different from most of pear cultivars such as ‘Gengtouqing’ in which malic acid is the predominant acid type. It was found that ‘Yandangxueli’ accumulated citric acid for three times against that in ‘Gengtouqing’ at fruit ripening stage. To investigate the mechanism of citric acid accumulation in ‘Yandangxueli’, organic acids content, gene expression and enzyme activity were studied in both cultivars. Five genes, Pp:mtCs, Pp:cyAco, Pp:cyIdh, Pp:mtMdh and Pp:cyMe which encoded citric synthase (CS), cytosolic aconitase (cyACO), NADP-dependent isocitrate dehydrogenase (NADP-IDH), NAD-dependent malate dehydrogenase (NAD-MDH) and NADP-dependent malic enzyme (NADP-ME) respectively, were identified from pear fruit. Their expression profiles and the corresponding enzyme activities were determined throughout fruit development in both cultivars. Results from these enzymes indicated that there were no strict relationship between gene expression, enzyme activity and citric acid accumulation. Expression analysis for two Py:vVAtp genes encoding vacuolar H⁺-ATPase A subunit and one Py:vVpp gene encoding Vacuolar H⁺-pyrophosphatase showed that they were all with up-regulated expression at the later development stage of ‘Yandangxueli’ but with down-regulated expression in ‘Gengtouqing’. Therefore, it is concluded that the different ability in citric acid transportation and storage might be involved in the high citric acid content in ‘Yandangxueli’.     

Effect of Citrate Concentration on the Extraction Efficiency of Selected Micronutrients from Soil

This study was carried out with the objective of evaluating the effect of citrate concentration on the extraction efficiency of some micronutrients from soil. Composite surface soil samples (0–20 cm) were collected from Eastern Harage Zone (Babile and Haramaya Districts), Wolaita Zone (Damot Sore, Boloso Bombe, Damot Pulasa and Humbo Districts) and Dire Dawa Administrative Council in purposive sampling. The treatments were arranged in completely randomized design (CRD) with three replications. A greenhouse pot experiment with soybean plant was conducted to determine the correlation between soil test methods and the selected micronutrients, such as iron (Fe), copper (Cu), manganese (Mn) and zinc (Zn) in the leaves of the plant. The results showed that, among the different citrate concentrations with strontium chloride (SrCl₂) tested for the determination of available Fe, Mn and Zn, the highest correlation coefficients (r = 0.82, p < 0.05), (r = 0.96, p < 0.001) and (r = 0.98, p < 0.001) were found between the diethylenetriamine pentaacetic acid (DTPA) method and 0.02 M strontium chloride (SrCl₂)-0.025 M citric acid extractant, respectively. Therefore, 0.02 M SrCl₂-0.025 M citric acid extractant is considered to be the most effective for the determination of Fe, Mn and Zn in soils of the studied areas. Similarly, high correlation coefficients (r = 0.97, p < 0.001) were found between DTPA and 0.02 M SrCl₂-0.05 M citric acid and (r = 0.88, p < 0.01) between DTPA and 0.02 M SrCl₂-0.025 M citric acid extractants for the determination of available Cu from soils. Hence, the 0.02 M SrCl₂-0.05 M citric acid extractant was shown to be the best for the determination of Cu in soils of the studied areas. However, considering the use of universal extractant, the 0.02 M SrCl₂-0.025 M citric acid extractant could easily be adopted as a procedure for the determination of Fe, Cu, Mn and Zn for both agricultural and environmental purposes. The greenhouse experiment confirmed the result.     

柠檬酸对三种人工合成氧化铁磷吸附特性的影响

试验采用了3种人工合成的氧化铁为材料,研究了氧化铁对磷的吸附以及柠檬酸对氧化铁磷吸附特性的影响。结果表明:3种人工合成的氧化铁对磷的吸附特性及柠檬酸对氧化铁吸附磷的影响都可用Langumir方程来描述,都达到了极显著水平。从磷的最大吸附量(Sm)、吸附反应常数(K)和最大缓冲容量(MBC)来看,未加入柠檬酸时,水铁矿对磷的吸附在容量和强度方面均为最高;而在加入柠檬酸时,3种人工合成的氧化铁对磷的吸附能力的顺序并无差别,水铁矿和针铁矿的磷Sm和MBC要比赤铁矿大很多。     

柠檬酸在早期断奶仔猪日粮中的应用

将４８头早期断奶仔猪分为３组,其中两个试验组分别加入柠檬酸０．７％（１组）和１．０％（２组）,另一组不加为空白对照。３周试验结果表明,日增重１组和２组分别比对照组提高１２．１８％和２．２４％,组间差异不显著（Ｐ＞０．０５）。饲料利用率１组和２组分别比对照组提高５．５６％和１５．６９％。头均全期经济效益１组和２组比对照组提高１２．７７％和６．３２％,１组又比２组提高６．０６％。     

营养因子对黑曲霉发酵生产柠檬酸的影响

[目的]研究营养因子对黑曲霉发酵生产柠檬酸的影响。[方法]通过发酵试验考察了营养条件与柠檬酸产量的关系。[结果]单因素试验表明,柠檬酸发酵的发酵最佳时间为120 h,最佳碳源为蔗糖,最佳氮源为(NH4)2SO4。正交试验结果表明,最佳培养基配比为:蔗糖10%,(NH4)2SO40.4%,MgSO4.7H2O 0.025%,pH值6.0。[结论]确定了黑曲霉发酵柠檬酸的较优配方,为柠檬酸的工业高效生产提供理论参考依据。     

光周期对扁豆真叶内源激素及游离氨基酸含量的影响

试验研究了不同光周期诱导对扁豆发育进程的影响，结果表明16h光周期诱导显著延迟了初花期和初荚期，其他处理差异不显著、初花节位随光照处理时数的增加而升高。在整个诱导过程中。SD(8h、10h)处理下真叶内的游离氨基酸含量高于LD(14h、16h)处理下的；赤霉素(GA)，峰出现时间与光处理时间正相关；脱落酸(ABA)峰出现的时问与光处理时数负相关；细胞分裂素(CTK)在各处理中均呈倒“V”形趋势，其含量随光周期处理时数的增加而增加。扁豆光周期诱导过程中，真叶内各激素及同化物参与了成花诱导。SD处理能使扁豆GA形成高峰时间提前，使ABA高峰延后，而LD处理则正相反。LD处理使CTK含量高于SD处理。GA、CTK与ABA是所有影响扁豆成花的激素中起主要作用的激素。推测：相对短日植物扁豆的成花信号中多种内源激素和游离氨基酸共同起重要作用，它可能是数量性状，当这一信号高峰出现并达到一定量时，引起成花反应，进而导致花的开放。     

酸化饲粮对仔猪几种血液生化指标的影响

本研究以柠檬酸为酸化剂,选择269头29±1—59±1日龄的大约克夏和长白仔猪,分三次试验,分析了酸化饲粮对仔猪血清胰岛素、脂肪酶、甘油三酯、游离脂肪酸、血糖、总蛋白等六种生化指标的影响。结果表明,采食酸化饲粮后仔猪血清胰岛素浓度提高,脂肪酶活力下降(P>0.05),甘油三酯含量降低(P>0.05).游离脂肪酸含量降低(P<0.05),血糖浓度下降(P<0.05),总蛋白含量提高(P<0.01)。胰岛素浓度的提高进而使合成代谢加强是酸化饲粮促进仔猪生长的重要生化基础。     

活性乳酸菌饮料中发酵乳酸度与柠檬酸用量关系的研究

为了研究活性乳酸菌饮料中发酵乳酸度与柠檬酸用量的关系,本实验首先对影响口味的各因素(糖量、柠檬酸量、发酵乳酸度)最适范围进行了确定,然后通过三因素三水平选出最佳配比,最后以最佳配比的酸度为标准,在加糖量为5.5%时,测得了不同发酵乳酸度下所需柠檬酸的量。结果表明:发酵乳酸度与柠檬酸用量可以作出一条线形曲线。     

Morpho-pomological and chemical characterization of pomegranate (Punica granatum L.) genotypes in Apulia region,Southeastern Italy

A recent increasing demand in Western countries for pomegranate products by consumers is especially supported for the nutritional and medicinal characteristics, due to the antioxidant properties of this fruit. Some studies have been published on the morphological and biochemical characteristics of pomegranate fruits in some Mediterranean countries, but little information is available about the genotypes present in Italy and in particular in Apulia (Southeastern region of Italy). This study (2008–2009) evaluated morpho-pomological and chemical parameters of eight pomegranate genotypes localized in private small orchards. Significant differences were observed among the pomegranate genotypes for many of the parameters investigated. In particular, fruit weight ranged from 168.9 g (SouMol) to 574.9 g (SouOst), °Brix from 14.7 (ComTri) to 18.0 (SouMol), titratable acidity from 5.4 (ComMol) to 25.0 (SouTri) g/L. SouMol showed the highest polyphenols (97.1 mg/L) and vitamin C (236.3 mg/L) contents. Oil content of the seeds was between 5.90% and 10.30%, no differences have been observed for the fatty acid composition with conjugated linoleic acid (CLA) isomers as the most abundant fraction (81.23%). Considering all the evaluated parameters, and especially those referring to the organoleptic characteristics and antioxidants content, it must be stated that the best genotypes worthy to be considered from agricultural and industrial points of view were AdeSgi for fresh market and SouOst for the juice industry.     

柑橘果实柠檬酸代谢研究进展

柑橘果实中柠檬酸含量是决定果实品质好坏的重要因素之一.综述柑橘成熟果实中有机酸的种类、柑橘果实发育过程中柠檬酸的代谢、调控、相关酶及柠檬酸代谢的分子生物学研究等内容;详细介绍柠檬酸的代谢途径及相关酶活性的变化,并提出今后的研究方向、思路和需要解决的问题.