哈姆林甜橙蔗糖合酶Ⅰ和酸性转化酶基因表达与果实糖积累的关系

蔗糖合酶(Sucrose synthase,SS)与酸性转化酶(Acid invertase,AI)是甜橙糖代谢过程中的两个关键酶,SS催化尿嘧啶核苷二磷酸葡萄糖和果糖合成蔗糖的可逆反应,AI则不可逆的催化蔗糖分解为果糖和葡萄糖,它们在甜橙糖代谢过程中起着重要作用。笔者以哈姆林甜橙品种为试验材料,采用半定量RT-PCR法,对4个时期哈姆林叶片中的SSI基因和AI基因的表达进行了分析。结果表明,4个时期哈姆林叶片中均可检测到SSI基因和AI基因在转录水平上的表达,但表达量存在差异。SSI基因在果实发育过程中表达量呈低-高-低-高趋势。AI基因在哈姆林果实发育成熟过程中的表达逐渐减弱,与果实糖累积呈负相关。     

马铃薯块茎还原糖的测定方法比较

对传统的铜还原-碘量法和3,5-二硝基水杨酸比色法测定块茎烘干样中的还原糖进行了比较研究。结果表明,比色法的准确性和精密性均稍好于铜还原-碘量法,且操作简便、快速、环境及人为因素对其影响较小。     

甘蔗SPS基因家族成员表达与糖分积累关系解析

以甘蔗高糖品种福农95-1702和低糖品种ROC-5为材料,分析SPS I、Ⅱ、Ⅲ、Ⅳ、Ⅴ在高、低糖这两个品种的幼叶、第三功能叶和不同蔗茎的表达,测定甘蔗糖分积累早期、中期和后期的糖分含量。结果显示,在功能叶和茎第二节中,三个阶段SPS家族成员在高糖品种的含量整体趋势高于低糖品种,结合蔗糖积累特点分析表明其可能在蔗糖合成中扮演着重要的角色。与正三叶相反,在幼叶中,三个阶段SPS家族成员在高糖品种的表达量整体趋势低于低糖品种,表明其可能与嫩叶的生长等其他生理性状相关,在成熟茎中,随着蔗糖积累时间的增加,高糖品种中的优势表达基因减少,而低糖品种中的优势表达基因增加,这可能与低糖品种中、后期大量积累蔗糖相关。     

Rate of Cooling Alters Chip Color,Sugar Contents,and Gene Expression Profiles in Stored Potato Tubers

When stored at temperatures below 10 °C, potatoes accumulate sucrose and the reducing sugars glucose and fructose. This process, cold-induced sweetening, has been studied extensively because potatoes with elevated reducing sugar contents produce undesirable, dark-colored products and acrylamide, a suspected carcinogen, during high-temperature cooking. Potatoes in commercial storages are cooled slowly, but many research studies have used potatoes cooled rapidly. In this study, effects of cooling rate and variety on chip color, sugars, and gene expression were examined. Sucrose and reducing sugar contents were substantially lower in slowly cooled than in rapidly cooled tubers of ‘Snowden’ and “MegaChip’ for the first 11 weeks after cooling to 3 °C began. Differences in gene expression for VInv, β-amylase, SPS, AGPase and GBSS were observed between cooling treatments and varieties. Overall, the data showed that cooling rate, time in storage, and variety influenced multiple aspects of cold-induced sweetening.     

Resistance of Potato Tubers to a Highly Aggressive Isolate of Phytophthora infestans in Relation to Tuber Age

The goal of these studies was to evaluate the influence of tuber age on the expression of resistance to Phytophthora infestans in five selected potato genotypes (three cultivars and two clones) varying in tuber resistance and maturity type, and also to select the best time for testing potato tubers for resistance to blight. Resistance was evaluated by inoculating whole tubers at 13 different times as they progressively aged during growth and storage. Tuber age was expressed as weeks after planting. Tubers were rated from week 13 (late July) until week 43 (late February) for tubers planted on 27–28 April, over three consecutive seasons (2001–2003). Analysis of variance performed on tuber resistance data showed significant effects of genotype, year and tuber age. Significant contributions of genotype × year, genotype × tuber age, year × tuber age and year × genotype × tuber age interactions were also detected. A slight increase in tuber resistance with tuber age was observed for cvs Bzura, Sokół and Irga, while the opposite trend was observed for the clones 97-A-63 and DG 92-227. Changes in tuber resistance with age of tested genotypes were not related to their maturity type. The period of most stable expression of tuber resistance was observed when tubers were tested between the 16th and 28th week after planting.     

Glycoalkaloid Concentration in Potato Tubers Related to Storage and Consumer Offering

Steroidal glycoalkaloids (SGA) are unwanted potato constituents for consumers because they are highly toxic and therefore have to be controlled in the food chain. Three experiments were carried out focusing on storage aspects and on exposure to artificial light at the point of sale. The experiments showed that an elevated temperature (10 °C) during long-term storage without sprouting inhibitors led to an increase in SGA contents (up to 518 mg SGA kg⁻¹ dry matter) in two of three investigated cultivars independent of the sprouting level. Cold storage (4 °C) slightly enhanced SGA contents in two cultivars. Sprout control resulted in a tendentious decrease in SGA contents in a set of another three cultivars. Growing location and wet and cool seasons had an influence too. Moderate exposure to light resulted in an increase in SGA in autumn, but in a decrease in spring time. Again, cultivars tested responded differently. The addressed factors have to be considered when developing strategies in minimising SGA level in table potatoes.     

菠萝酸性转化酶基因家族初步生物信息学及表达分析

酸性转化酶（acid invertase, AIN）在菠萝采后蔗糖降解过程中起着重要作用,基于菠萝全基因组数据库,预测菠萝AIN家族基因并进行生物信息学分析,解析其在采后菠萝不同贮藏温度下的表达变化情况,为阐明AIN基因在采后菠萝果实贮藏特性中的作用奠定基础。以水稻AIN家族基因为探针,在菠萝全基因组中鉴定到2个菠萝细胞壁酸性转化酶基因（cell wall acid invertase, CWIN）和2个液泡酸性转化酶基因（vacuolar acid invertase, VIN）,分别命名为AcCWIN1、AcCWIN2、AcVIN1、AcVIN2,设计编码区引物进行测序验证,并进行生物信息学分析。进化分析结果表明,AcCWIN1、AcCWIN2和AcVIN1、AcVIN2蛋白分别归于细胞壁酸性转化酶和液泡酸性转化酶2个进化支上,且均属于糖基水解酶家族GH32,基因结构、保守域和保守基序均一致。荧光定量分析结果表明,菠萝果肉中AcVIN1和AcVIN2在果实采后贮藏过程中表达量升高,且AcVIN1在发生黑心病的部位大量表达,而AcCWIN1和AcCWIN2在采后贮藏过程中表达量逐渐降低,且随着贮藏温度的升高其表达量降低,预示AcVIN1、AcVIN2较AcCWIN1、AcCWIN2在菠萝采后蔗糖降解和黑心病的发生方面发挥着更为重要的作用。     

毛叶枣果实发育过程中糖分的积累规律

研究高朗1号、新世纪、蜜枣和缅甸长果4个毛叶枣品种果实发育过程中可溶性糖分的组成及其变化.结果表明:毛叶枣果实可溶性糖组分主要是蔗糖、葡萄糖和果糖;在果实发育初期,糖含量少,果实中蔗糖积累始于果实膨大中后期,直至成熟期;高朗1号、新世纪果实中果糖与葡萄糖的积累规律较相似,其含量变化不明显;蜜枣和缅甸长果果实中果糖的积累速度明显快于葡萄糖的.     

低温胁迫对木薯幼苗叶片转化酶及可溶性糖含量的影响

以华南124(SC124)、华南8号(SC8)和阿根廷7号(ARG7)3个木薯品种为材料,研究在持续低温胁迫下木薯幼苗叶片转化酶活性(SAI,NI)及可溶性糖含量的变化。结果表明:可溶性酸性转化酶(SAI)在木薯耐寒品种中(ARG7)活性较高;低温胁迫均能提高3个品种木薯中SAI酶的活性,但是在耐寒品种ARG7中表现为稳定提高。中性转化酶(NI)在木薯耐寒品种中(ARG7)活性较高,低温胁迫也能提高3个木薯品种中的NI酶活性,而NI酶活性均表现为短期提高。初步推断,SAI活性与木薯的抗寒存在一定的正相关。低温胁迫后3个木薯品种叶片蔗糖、还原糖和可溶性总糖的含量均升高,且抗寒品种ARG7叶片的还原糖、蔗糖和可溶性总糖含量极显著高于SC124和SC8。     

Coordinated Regulation of Cold Induced Sweetening in Tetraploid Potato Families by Isozymes of UDP-Glucose Pyrophosphorylase and Vacuolar Acid Invertase

Past investigations have suggested that both UGPase and AcInv activities can be used as markers to screen genetically diverse potato clones for cold induced sweetening resistance (CIS-R). The goal of this study was to define their cooperative interaction in regulating sweetening. Inter- and intra-ploidy hybridizations of good (G) and poor (P) processing 24 or 48 chromosome potato clones were used to create 24 potato families. Potatoes were field grown and 460 progeny (≤20 each family) were stored for five months in the cold (4 C). Tubers from each progeny plant were evaluated for cold induced sweetening resistance (CIS-R) and correlated with the percentage of A-II isozymes of UDP-glucose pyrophosphorylase (UGPase; EC 2.7.7.9); and acid invertase activity (AcInv; EC 3.2.1.26). Each progeny was given a CIS-R score of 1–10 (1-most resistance, 10 least resistance). The families were grouped into four classes based on (1) high or low AcInv activity (low being a SA of 0.30 or less) (2) high or low percentage of A-II isozymes (low being 50% or less), and (3) CIS-R score. In high AcInv families, CIS-R was low regardless of the percentage of A-II isozymes present. In low AcInv activity families, there was a trend for average chip color to improve as the percentage of A-II isozymes increased from 0% to 40%. This increase in CIS-R in low AcInv families is likely due to the kinetic properties unique to the A-II forms of UGPase (principally UGP5) which limit the formation of sucrose via sucrose-6-phosphate synthase (SPS; EC 2.4.1.14). Lower concentrations of sucrose can lead to a decrease in reducing sugar production via vacuolar AcInv and lighter chip and fry colors. In selecting tetraploid parents, for the development of processing potato clones with improved CIS-R, it is recommended they have a basal AcInv SA of 0.30 or less and have A-II isozymes of UGPase.     

3,5-二硝基水杨酸(DNS)比色法测定马铃薯还原糖含量的研究

试验针对3,5-二硝基水杨酸(DNS)比色法测定马铃薯还原糖含量的吸收光谱及其对测定值可靠性的影响因素进行了研究。找到了分析马铃薯还原糖的最佳条件:λ射波长为510nm,显色剂用量为6mL,在沸水浴的显色时间范围为12～15min,结果表明该方法的灵敏度得到了提高。由于该方法具有方便、安全、成本低等优点,适合于常规实验室马铃薯还原糖批量和定量的测定。     

Control of the Potato Virus X Through Application of Root Extracts of Chlorophytum nepalense to Potato Plants and Tubers

The perennial herb Chlorophytum nepalense (Lindley) Baker, widely distributed throughout the northern parts of Tripura State of India, is used traditionally by Tripuri farmers as a root extract to control dark viral necrotic lesions of sprouted potato tubers and plants. The root extracts strongly reduced infection of potato plants and sprouted tubers by Potato virus X under glasshouse conditions. The root extract was found to contain the three plant-viricidal compounds chlorogenic acid, kaempferol-3-O-(3′,6′di-O-E-p-coumaroyl)-β-d-glucopyranoside, and luteolin and suggests that the isolated compounds may have the potential to be used as natural plant-viricidal compounds.     

Effects of Different Nitrogen Application Rates on Starch Accumulation,Starch Synthase Gene Expression and Enzyme Activity in Two Distinctive Potato Cultivars

Nitrogen (N) is the most important nutrient for potato growth. N fertilizer has an important effect on the tuber yield and starch content in potatoes. In this study, taking the high-starch cultivar Kexin 22 and the low-starch cultivar Kexin 19 as experimental materials, three N fertilizer application rates—0, 150 and 300 kg/ha—were used to investigate the effects of different N application rates on starch accumulation and the expression of starch synthase genes in potato tubers with different starch contents. In the cultivar Kexin 22, the accumulations of amylose, amylopectin and total starch showed a ranking of N150 > N300 > N0 for the entire growth period. The cultivar Kexin 19 showed an accumulation pattern of N0 > N150 > N300 in the early growth period, N150 > N300 > N0 in the middle growth period and N300 > N150 > N0 in the late growth period. Compared with those in Kexin 19, the expressions of the glucose-1-phosphate adenyltransferase (AGPP-L), granule-bound starch synthase (GBSSI), starch-branching enzyme I (SBEI) and soluble starch synthase III (SSIII) genes in Kexin 22 were upregulated, whereas no obvious difference existed in the expression of the alkylglycerone phosphate synthase (AGPP-S) and soluble starch synthase II (SSII) genes between the two cultivars. In Kexin 22, the different N application rates had a significant effect on the peak expression levels of AGPP-L, GBSSI, SBEI and SSIII but had a small effect on the peak expression time for these genes. Among these genes, most showed a ranking of N150 > N300 > N0 in the early and middle growth periods, and all showed a ranking of N300 > N150 > N0 in the late growth period; most showed a peak expression time on the 65th day after emergence (DAE 65). In Kexin 19, the different N application rates had a significant effect on the peak expression levels and peak expression times of the AGPP-L, GBSSI, SBEI and SSIII genes. Among these genes, all showed a ranking of N0 > N150 > N300 in the early growth period, whereas most showed a ranking of N150 > N300 > N0 in the middle growth period, and all showed a ranking of N300 > N150 > N0 in the late growth period. In Kexin 19, the peak gene expression was shifted to an earlier date under the low N levels, and it was delayed under the high N levels. The effects of the N application rate on the activities of starch synthases AGPP, GBSS, SSS and SBE showed largely the same trends as those in the expression levels of the related genes. Therefore, to obtain a high harvest of starch yield, different N application rates should be recommended for different cultivars.     

氮素水平对马铃薯干物质积累及库活性的影响

为了探讨内蒙古阴山以北地区马铃薯生产中氮肥适宜施用量,以‘克新1号’品种为材料,采用田间小区试验的方法,研究了氮素水平对马铃薯干物质积累及库活性的影响。结果表明:在当地土壤肥力条件下,马铃薯干物质积累量与库活性均表现出随施氮量的增加呈先增加后降低的趋势。在360 kg/hm2施氮量下,马铃薯公顷干物质积累量、单株叶片干物质积累量、单株块茎干物质积累量和库活性均最大,分别为5 989.81 kg/hm2、20.03 g/株、84.32 g/株、0.072 g/g·d。因此,360 kg/hm2的施氮量,可以作为当地马铃薯生产中的最佳氮肥施用量。     

Sugar-Starch Metabolism and Antioxidant Potential in Potato Tubers in Response to Different Antisprouting Agents During Storage

Single applications of different antisprouting agents like hot water treatment, spearmint oil and clove oil were carried out on potato cultivar “Lady Rosetta” to compare their efficacy with that of synthetic chloro isopropyl N-phenyl carbamate (CIPC). The tubers were stored at ambient storage conditions (25?±?2 °C) for 81 days to assess changes in their sugar-starch concentrations and antioxidant potential. Antioxidant potential in the tubers was assessed as their total phenolic concentrations and radical scavenging activities. In addition, the enzymatic activities were also determined in order to evaluate the possible depletion of these antioxidants as substrate during storage. Results revealed significant response of stored potatoes to all antisprouting agents compared with the control (P?≤?0.05). CIPC and clove oil applications maintained tuber dormancy almost twice as long (81 days) as observed in the control (45 days). Application of spearmint oil and hot water treatment maintained tuber dormancy for almost 2 months. However, it was associated with an increased percentage sprouting during the last weeks of storage. At the end of storage, the highest starch (16.83%) and lowest sugar (0.99%) concentrations were estimated after CIPC application and maximum total phenolic concentration (143.57 mg gallic acid equivalent (GAE)/100 g), and highest antioxidant activity (39.73%) were found after clove oil application. Enzymatic activities were not statistically different between CIPC and clove oil application during most of the storage period. Results showed that efficient replacement of CIPC with clove oil in the premium potato cultivar might be useful; this may avert related food safety and environmental issues and would also ensure organic potato storage.     

Effect of Growth Regulators and Ethanol on Termination of Dormancy in Potato Tubers

The main objective of this study was to find the best practice of inducing the sprouting of dormant potato tubers. We compared two protocols of breakage of dormancy, which are based on dipping excised potato eyes in an aqueous solution of gibberellic acid (GA₃) and kinetin (standard 1) or in the aqueous solution of GA₃, thiourea, and daminozide (standard 2), with a newly reported approach based on ethanol. We tested the effect of ethanol alone or in combination with GA₃ and/or kinetin on dormancy release and sprouting of the potato tubers. As a model, we used two potato genotypes (cultivars Pasat and Dorota), with long dormancy of 5 and 10 weeks respectively. We showed that the standard 2 was the most effective treatment both for dormancy breaking and in promoting sprout growth, especially for cv. Dorota, for which the treatment induced 82.3% of tuber eye-plugs to sprout 28 days after treatment and to produce 93.2% of emerged plants after subsequent 28 days of cultivation in the greenhouse. For this cultivar, similar efficacy was observed for the combination of 4% ethanol with GA₃ and kinetin. The same concentration of ethanol combined with GA₃ but without kinetin was the most efficient treatment for breaking dormancy of cultivar Pasat. However, the difference between the various treatment combinations was statistically insignificant. Ethanol alone or in combination with kinetin poorly induced breakage of dormancy, confirming the main role of GA₃ in artificial dormancy breaking. Thus our study showed that the standard 2 is the most effective approach for breakage of dormancy at least with long term-dormancy cultivars.     

马铃薯贮藏块茎低温糖化研究进展——(Ⅰ)生理生化机理

马铃薯低温贮藏造成还原糖积累是影响块茎加工品质最重要的因素,有关低温糖化机理一直是马铃薯品质改良研究的热点。本文总结了马铃薯基因型、环境因子、ABA和生物膜组成变化对还原糖积累的影响,重点从生理生化水平上探讨了块茎碳水化合物代谢路径变化与还原糖积累的关系,为抑制还原糖含量改良块茎品质打下了理论基础。     

Glyphosate Carryover in Seed Potato: Effects on Mother Crop and Daughter Tubers

Field studies were conducted in 2008 and 2009 in Aberdeen, ID, Ontario, OR, and Paterson, WA to determine the effect of simulated glyphosate drift on ‘Ranger Russet’ potato during the application year and the crop growing the next year from the daughter tubers. Glyphosate was applied at 8.5, 54, 107, 215, and 423 g ae ha^?1 which corresponds to 1/00, 1/16, 1/8, ¼, and 1/2 of the lowest recommended single-application rate for glyphosate-resistant corn and sugar beet of 846 g ha^–1. Glyphosate was applied when potato plants were at 10 to 15 cm tall (Early), or at stolon hooking (H), tuber initiation (TI), or during mid-bulking (MB). In general, the MB applications caused less visual foliar injury to the mother crop than earlier applications at ID or OR, and H applications at WA. Mother crop injury increased as glyphosate rate increased regardless of location, application timing, and rating date. U.S. No.1 and total tuber yields were usually related to the injury level resulting from glyphosate application timings and rates. Although injury to the mother crop from glyphosate applied at MB usually was the lowest compared to injury from other application timings, when daughter tubers from that timing were planted the following year, emergence, plant vigor, and yield was most detrimentally impacted compared with that of daughter tubers from other timing treatments. MB daughter tuber emergence was less than 30 % of the nontreated control tuber emergence while emergence of daughter tubers from the other treatments was 60 to 95 %. As rate of glyphosate applied to the mother crop increased, daughter tuber emergence decreased. When MB daughter tubers did emerge, plants were chlorotic and stunted as if the plants had been directly sprayed with glyphosate. Regardless of whether the daughter tubers had defects or not, results the following year were the same. Implications are that if a mother seed crop encounters glyphosate during bulking, injury may not even be noticeable on the foliage or the tubers, however, emergence, vigor, and yield of the crop growing the following year from the daughter tubers could be greatly impacted.     

Mosaic Virus Symptoms in Potato Crops and the Occurrence of Growth Cracking in Tubers

Infection of potato plants by viruses causing mosaic symptoms may result in a reduction in crop yield, depending on severity of symptoms and incidence. In 2004 and 2007, an investigation was undertaken to examine the relationship between plants with mosaic symptoms and the occurrence of growth cracking in daughter tubers. Samples of pairs of plants affected by mosaic symptoms and plants with no symptoms were collected from nine potato crops, of which seven were cv. Estima, containing at least 20% mosaic-affected plants. Growth cracking was more prevalent on mosaic-affected plants of cv. Estima than on plants with no symptoms. The incidence of growth cracking was much greater on plants showing mosaic symptoms caused by a mixed infection of Potato virus A and Potato virus V together than on symptomatic plants infected by either virus alone. The presence of virus in plants with no symptoms did not affect the incidence of tubers affected by cracking. In a crop of the advanced selection Blue Tzar, plants with mosaic symptoms caused by Potato virus Y ^N produced more tubers with cracking than plants with no symptoms. Growth cracking did not occur in the one sampled crop of cv. Désirée infected by Potato virus A.