Quantitative comparison of individual sugars in cultivars and hybrids of taro [<Emphasis Type="Italic">Colocasia esculenta</Emphasis> (L.) Schott]: implications for breeding programs

Taro [Colocasia esculenta (L.) Schott] is cultivated for its starchy corm consumed baked or boiled and processed in snacks (chips or French fries) to satisfy growing urban markets. Most consumers prefer non sweet taros. High content of sucrose (non-reducing sugar), glucose and fructose (reducing sugars) represent undesirable characteristics because they cause browning of the snacks. Breeding taro for improved corm quality is complex and phenotypic recurrent selection is impaired by the long growth cycle and the low vegetative propagation ratio. New high-throughput phenotyping tools are needed to select suitable hybrids in early clonal generations. The aim of the present study was to develop an HPTLC protocol for the quantitation of sugars in the fresh corm (FW). The individual sugars values in 60 hybrids released by four different breeding programs were compared with 300 cultivars from six different countries. Sucrose, glucose, fructose, maltose and ribose were quantitated. Mean total sugars varied from 1.83 to 6.28%FW in hybrids and from 1.32 to 7.69%FW in cultivars. The ratio sucrose/reducing sugars varied from 0.06 to 4.34 in hybrids and from 0.04 to 4.82 in cultivars. The protocol developed in this study is rapid, cost efficient, environment-friendly and more accurate than previous techniques based on dry matter because sample preparation is known to affect chemical composition of individual sugars. This technique can be used in taro breeding programmes for the early detection of undesirable hybrids with high levels of reducing sugars.     

Modified atmosphere packaging of yellow and purple plum cultivars. 2. Effect on bioactive compounds and antioxidant activity

Changes in bioactive compounds (total phenolics and total carotenoids, and individual anthocyanins) as well as total antioxidant activity (TAA) in separate fractions; hydrophilic (H-TAA) and lipophilic (L-TAA), in the peel and the flesh of 2 purple and 2 yellow skin plum cultivars under modified atmosphere packaging (MAP) conditions, using two films with different gas permeability, were studied. Results revealed that in all cultivars, total phenolics and H-TAA increased in the peel and flesh during storage, as well as the two identified anthocyanins: cyanidin-3-glucoside and cyanidin-3-rutinoside in the purple cultivars. These changes were significantly delayed in fruit stored under MAP conditions. Total carotenoids and L-TAA increased in the yellow cultivars (in both peel and flesh) while decreases were observed in the purple cultivars, these changes also being delayed by the use of MAP. Positive correlations were found between H-TAA and total phenolics and between L-TAA and total carotenoids.     

‘皮球桃’及其突变体类胡萝卜素积累及相关关键基因分析

本研究以‘皮球桃’及其芽变桃不同发育阶段的果肉与叶片中脉为试材,采用HPLC法测定两种桃中类胡萝卜素的组分构成与含量积累,并对类胡萝卜素生物合成及代谢过程中关键基因的转录水平进行实时荧光定量PCR分析。结果显示,芽变桃中类胡萝卜素总含量极显著高于‘皮球桃’,β-隐黄质、α-胡萝卜素和β-胡萝卜素的积累差异是造成两种桃呈色不同的主要原因。实时荧光定量PCR结果表明,CCD4在果肉和叶片中脉中的表达规律完全相同,且与类胡萝卜素的积累模式一致,因此CCD4的表达差异可能是导致芽变桃果肉及叶片中脉突变为黄色的重要原因。本研究利用‘皮球桃’及其自然突变体作为探讨类胡萝卜素合成及代谢调控的理想材料,以期从生理及分子层面揭示变异黄桃的形成机理,为桃的类胡萝卜素调控基因开发、变异的早期鉴定、认识和选育富含类胡萝卜素桃品种提供理论基础。     

Changes in hydrophilic and lipophilic antioxidant activity and related bioactive compounds during postharvest storage of yellow and purple plum cultivars

Eight plum cultivars (four dark-purple and four yellow) were harvested at the commercial ripening stage, and changes of fruit quality properties were evaluated during cold storage and subsequent shelf-life, with special emphasis on bioactive compounds (phenolics, anthocyanins and carotenoids) and antioxidant activity (TAA). From the eight plum cultivars, four showed the typical climacteric ripening pattern (‘Blackamber’, ‘Larry Ann’, ‘Golden Globe’ and ‘Songold’) while four behaved as suppressed-climacteric types (‘Golden Japan’ ‘Angeleno’, Black Diamond’ and ‘TC Sun’), the latter being described for the first time. At harvest, large variations in phytochemicals and antioxidant activity were found among cultivars in peel and pulp tissues, although phytochemical concentration and antioxidant activity were higher in the peel than in the flesh (2–40-fold depending on the bioactive compound). During storage, increases in total phenolics for all cultivars (peel and pulp), in total anthocyanin content in the peel of the dark-purple plums, and total carotenoids in the peel and pulp of the yellow cultivars were observed. This behaviour of the bioactive compounds was reflected in TAA changes, since hydrophilic-TAA (H-TAA) was correlated with both phenolics and anthocyanins, while lipophilic-TAA (L-TAA) was correlated with carotenoids. L-TAA comprised about 30–50% of the TAA in plum tissues. Carotenoids and phenolics (and among them the anthocyanins) could be the main lipophilic and hydrophilic compounds contributing to L-TAA and H-TAA, respectively. No significant loss of bioactive compounds and TAA occurred during prolonged plum storage. Moreover, for a better evaluation of the antioxidant potential of plums, the contribution to carotenoids should not be overlooked.     

First genetic maps and QTL studies of yield traits of taro (Colocasia esculenta (L.) Schott)

The paper presents the first taro (Colocasia esculenta L. Schott) genetic maps. Taro is an important vegetatively propagated root crop species in most subtropical areas. It is an allogamous and protogynous species with a basic chromosome number of x = 14. Two F₁ progenies of 123 and 100 individuals obtained from crosses between local cultivars from Vanuatu (VU101 × VU104 and VU373 × VU314) were chosen for this study. Both genetic maps contained 169 markers, mainly AFLPs and 8 SSRs, and were characterised by a high density of markers and a short map length. The maps had 14 and 18 linkage groups (LG) respectively and were not completely saturated. Twenty-four markers were identified across the two progenies and a good co-linearity was observed for the majority of these markers. A QTL detection study was conducted on both progenies with 91 and 89 individuals respectively. Several putative QTLs were identified for corm yield and corm dimensions (which were highly correlated traits) whereas no QTL was detected for dry matter content. This result was relatively unexpected since dry matter content was a more highly heritable trait than corm yield or corm dimensions. A major dominant gene, responsible for the yellow colour of the corm flesh, was also identified. Further mapping studies on taro should include a larger number of SSR markers, larger progenies should be created and other important traits related to yield and eating quality should be included in the QTL analyses.     

HPTLC screening of taro hybrids (Colocasia esculenta (L.) Schott) with high flavonoids and antioxidants contents

Taro (Colocasia esculenta) is the tropical root crop species featuring the greatest flavonoids diversity. Their quantification is important for breeding programmes focusing on biofortification. This study aims at developing an HPTLC protocol to compare the flavonoids fingerprints of more than 1800 hybrids belonging to 24 full‐sib families and to select genotypes with high levels of antioxidants. Twenty different chemical markers were identified based on bands R_f and colour. Flavonoids differ among individuals both quantitatively and qualitatively. Marker ‘A’ yielded the strongest antioxidant response to DPPH, equivalent to the one with quercetin pure standard. Overall, 377 high flavonoids content (HFC) hybrids were selected from 14 different families. The mean corm weight of HFC hybrids always appeared higher than the mean corm weight of the family they belong to. This method allows unambiguous selection of HFC hybrids. It also contributes to taro genetic improvement for nutritional value and access to new markets and to strengthen corm tolerance to pests and diseases. It could be applied to other tropical root crop species.     

Use of image analysis to estimate anthocyanin and UV-excited fluorescent phenolic compound levels in strawberry fruit

Strawberry is rich in anthocyanins, which are responsible for the red color, and contains several colorless phenolic compounds. Among the colorless phenolic compounds, some, such as hydroxycinammic acid derivatives, emit blue-green fluorescence when excited with ultraviolet (UV) light. Here, we investigated the effectiveness of image analyses for estimating the levels of anthocyanins and UV-excited fluorescent phenolic compounds in fruit. The fruit skin and cut surface of 12 cultivars were photographed under visible and UV light conditions; colors were evaluated based on the color components of images. The levels of anthocyanins and UV-excited fluorescent compounds in each fruit were also evaluated by spectrophotometric and high performance liquid chromatography (HPLC) analyses, respectively and relationships between these levels and the image data were investigated. Red depth of the fruits differed greatly among the cultivars and anthocyanin content was well estimated based on the color values of the cut surface images. Strong UV-excited fluorescence was observed on the cut surfaces of several cultivars, and the grayscale values of the UV-excited fluorescence images were markedly correlated with the levels of those fluorescent compounds as evaluated by HPLC analysis. These results indicate that image analyses can select promising genotypes rich in anthocyanins and fluorescent phenolic compounds.     

红叶山茶(Camellia japonica)叶片色素含量与叶色参数的相关性分析

以3个红叶山茶品种‘红叶黑魔法’、‘黑魔法’和‘黑蛋石’为试验材料,分别测定叶片不同发育阶段叶绿素、类胡萝卜素、总花青苷含量及叶色参数L~*、a~*、b~*值,并通过相关性分析探讨叶色参数与叶片色素含量变化之间的关系。结果表明,首先,3个不同发育阶段叶片中叶绿素a、叶绿素b和类胡萝卜素含量呈上升趋势,不同品种同一发育阶段的色素含量相近。‘红叶黑魔法’和‘黑蛋石’叶片总花青苷含量在新叶展开10 d左右达到最大值,此后极显著下降,而‘黑魔法’叶片的花青苷含量则变化不大。其次,从色素比值来看,在新叶展开10 d时,花青苷的所占比值最大,‘红叶黑魔法’和‘黑蛋石’的花青苷比值分别达到87.88%和79.08%,极显著地高于叶绿素所占比值。到50 d时,花青苷比值下降至31.74%和23.68%,且3个品种花青苷含量相近,而叶绿素和类胡萝卜素比例则显著增加,这一结果较好地解释了这3个品种叶片的呈色变化,说明花青苷含量及其各种色素含量的比例变化是导致红叶山茶叶色变化的主要原因。最后,3个品种的a*值均与花青苷含量呈显著正相关,而与叶绿素a、叶绿素b、类胡萝卜素呈负相关,a~*值可作为描述红叶山茶品种叶色变化的代表性参数。     

Changes in the Functional Components and Radical Scavenging Activity of Korean Maize Hybrids According to Different Cropping Seasons

We evaluated the proximate composition, free sugar content, fatty acid composition, carotenoid content, total phenol content, and radical scavenging activity of the grain from various Korean maize hybrid cultivars grown in two different cropping seasons. The moisture, crude ash, crude fat, crude protein, total starch, and amylose contents were significantly higher in most of the maize hybrid cultivars when grown in the early-season than when grown in the late-season. The free sugar content, fatty acid composition, carotenoid content, and total phenol content differed significantly between cultivars and cropping seasons. The highest unsaturated fatty acid compositions of maize hybrids of early-season and late-season were 86.05 and 86.29%, respectively, in the Daanok cultivar. The carotenoid contents were significantly higher in maize hybrids of late-season compared to those of early-season. The highest total phenol content was 108.09 mg/100 g in Singwangok of the late-season. The radical scavenging activity of maize hybrids differed significantly between cultivars and cropping seasons.     

设施桃果实品质发育生理研究

以设施栽培的曙光、早红珠、春捷为试材,研究了桃果实发育过程中,主要品质指标的变化动态。结果表明:维生素C、可溶性蛋白、果皮叶绿素和类胡萝卜素含量随着果实的发育呈下降趋势,总糖、可溶性固形物含量及糖酸比不断增加。可滴定酸、总糖、维生素C和类胡萝卜素含量均在果实接近成熟期迅速变化。果实中淀粉含量很低且呈下降趋势,只是在果实发育前期有所升高。果实中干物质含量变化在花后50d内变化趋势是由低到高,此后,三者呈现不规则变化。可溶性蛋白在果实内含量由高到低递减,前期降减程度最大,后期含量保持相对稳定,其变化规律与果实生长一致。     

Phenotypic segregation and relationships of agronomic traits in Monastrell × Syrah wine grape progeny

The aim of this work was to study the phenotypic segregation of different agronomic and fruit quality traits, and their relationships, in Monastrell × Syrah wine grape progeny. Twenty-two agronomic traits were evaluated and compared for three consecutive years in this progeny. The results show the phenotypic diversity existing in a cross between two different wine grape cultivars. Most of the phenological, productive, morphological, and enological parameters evaluated displayed continuous variation within the progeny, suggesting a polygenic inheritance. Some correlations between traits were detected by the Spearman correlation test, although high coefficients were not found for most of them. Cluster analysis of the progeny grouped the hybrids based on criteria with significance for wine grape breeding. Also, we investigated the relationship between the skin color and total content of anthocyanins with the VvmybA genotype, using the CAPS (Cleaved Amplified Polymorphic Sequence) marker 20D18CB9. The results show that hybrids with two copies of the functional color allele tend to have increased anthocyanins content. Based on this study, 14 genotypes were pre-selected from the breeding population for additional quality studies.     

Cell wall physicochemical aspects of peach fruit related to internal breakdown symptoms

The aim of this study was to dissect the physicochemical aspects of cell wall components in relation to chilling injury symptoms, expressed as flesh browning and postulated as internal breakdown in the present study, in a non-melting peach cultivar (Prunus persica L. Batsch, cv. Andross) during ripening after 4 weeks cold storage at 5 °C. Uronic acids, neutral sugars and cellulose contents were assayed in order to determine the correlation between them and flesh browning. Cation distribution in cell wall material and activities of pectin-modifying enzymes were also monitored. Uronic acid content was higher in both water-soluble and -insoluble pectin fractions in sound peach fruit compared to fruit with internal breakdown symptoms. The chilling-injured fruit were characterized by 26% higher content in total neutral sugars compared to sound fruit, which was mainly attributed to increased galactose, arabinose and glucose contents, whereas tissue derived from sound fruit had a 27% higher cellulose content compared to chilling-injured tissue. Decreased activities of both polygalacturonase and pectin methyl esterase, accompanied by decreased levels of cation binding in the cell walls, primarily of calcium, were recorded in the brown-fleshed tissue. Since the examined tissues originated from fruit subjected to common storage treatments, differences reported here are related to the development of internal breakdown symptoms.     

The production of inbred lines of brussels sprouts with dominant S-alleles

Summary The best sources of Brussels sprout inbred lines with both good agronomic characters and high self-incompatibility are likely to be cultivars of reasonably good agronomic type which have not been too intensively selected. Comparison of three cultivars of different agronomic quality showed that the cultivars of poor and moderate quality had about 55% of plants with a dominant S-allele, but the most highly selected cultivar had only 25% of such plants. A programme of S-allele screening is suggested which incorporates the minimum number of tests required to determine whether or not a particular plant has a dominant S-allele. A survey of S-alleles present in commercial F₁ hybrids showed that the frequency of dominant S-alleles was only 19% in hybrids released prior to the end of 1971, but was 50% in hybrids released since 1971.     

Breeding of cabbage (Brassica oleracea L. var. capitata) with fusarium wilt resistance based on microspore culture and marker-assisted selection

Cabbage Fusarium wilt (CFW), caused by Fusarium oxysporum f. sp. conglutinans, is one of the most devastating diseases of cabbage worldwide. In recent years, CFW has been spreading across northern Chinad. Thus, development of resistant cultivars is necessary to control CFW. Here we report microspore culture from a cross of two elite cabbage inbred lines, 96–100 (highly resistant to CFW) and 01–20 (highly susceptible to CFW), in order to obtain doubled haploids (DHs) to cultivate cabbage materials for resistance breeding. A total of 196 DHs were obtained in 2011 and 2012 and three elite DH lines were selected from them through agronomic trait evaluation as well as marker-assisted selection. These three elite DH lines were crossed with elite cabbage inbred lines to create hybrids, which were then evaluated for their resistance and agronomic traits. Three excellent hybrids were selected. The use of microspore culture and marker-assisted selection greatly shortened the time required to obtain these excellent hybrids. These resistant varieties may become an effective control of CFW in diseased areas.     

抗虫棉不同类型品种苗期耐盐理化特性差异研究

 为揭示不同基因型抗虫棉耐盐性差异的生理机制,指导抗虫棉耐盐品种鉴选和盐碱地棉花生产,以耐盐性差异显著的两类转Bt基因抗虫棉品种——耐盐性强的鲁K536、鲁棉研18优选系,耐盐性弱的新棉33B优选系、鲁K1258——为试验材料,利用不同盐分含量砂培与土培试验相结合,比较研究它们苗期的主要理化指标变化。结果表明,在NaCl胁迫下,耐盐性强的品种苗期叶片内的K⁺含量显著高于耐盐性弱的品种,Na⁺含量显著低于耐盐性弱的品种,丙二醛含量也显著低于耐盐性弱的品种,而游离脯氨酸、可溶性糖、类胡萝卜素含量均显著高于耐盐性弱的品种。耐盐性强的品种棉苗的过氧化物酶活性、叶绿素a、b和a+b含量以及净光合速率明显高于耐盐性弱的品种。表明棉花的耐盐性强弱因基因型而异,基因型间的耐盐性差异与丙二醛、脯氨酸、可溶性糖、类胡萝卜素含量和保护酶活性以及盐离子在叶片中累积量的差异有关。     

Components of partial resistance in phaseolus beans against an Ethiopian isolate of bean rust

Summary Banana weevil (Cosmopolites sordidus Germar) is a major limiting factor in the cultivation of plantains and bananas (Musa spp. L.) in sub-Saharan Africa. The larvae damage the crop by tunneling in the corm. Chemical control is feasible but not sustainable, whereas host plant resistance is safe and has long term benefits. Banana weevil damage and infestation levels and corm hardness were assessed in Musa germplasm in order to determine the genetic control and potential mechanisms of resistance to this insect pest. Susceptibility/resistance to weevil was measured by the percentage coefficient of infestation (PCI) and damage in cross sections (CS) of the corm. All plantains were equally susceptible to the banana weevil, while a wild banana accession and some cooking and dessert banana cultivars showed high levels of resistance. Differential genotypic responses were observed in euploid plantain-banana hybrids. Segregation results suggest that host plant response to weevil in Musa is controlled by gene(s) exhibiting partial dominance towards the resistant parent and modifier genes with additive and dosage effects for susceptibility in the plantain parent. In natural banana germplasm, resistant clones showed increased corm hardness, as measured by a penetrometer in longitudinal and cross sections of outer and central corm tissues. This might suggest a non-preference mechanism for weevil resistance. However, the lack of correlation between corm hardness with PCI and CS scores in the segregating progenies suggested that other mechanisms may be more important in conferring resistance to banana weevil.     

Golden rice: introgression, breeding, and field evaluation

Considerable progress has been made on the genetic engineering of rice for improved nutritional content involving micronutrients and carotenoid content. Golden Rice, developed by genetic engineering (Agrobacterium and biolistic transformation) was used in rice breeding for the transfer of high-nutritional value to the local rice cultivars. Simultaneously, commercial Asian indica rice cultivars were also developed with expression of high-carotenoid levels. The lines were developed based on POSITECH (PMI) selection system or made marker free by segregating out the marker gene from the gene of interest. Anther culture was used to develop the homozygous stable lines, which could be of much use in further introgress-breeding and in farmer’s field. Enhanced carotenoids levels (up to T3 generation) were observed in a number of lines compared to the T0-T1 seeds which could be due to transgeneration effect of growing under greenhouse versus field conditions. However, a few introgressed lines showed less carotenoid levels than the original lines used in the breeding process. Agronomic performance of introgressed lines, non-transgenic controls, and transgenic golden rice (IR64 and BR29) developed at IRRI showed acceptable and comparable data under identical limited field conditions (screenhouse data). Syngenta generated a new Golden Rice (US cultivar) containing high level of carotenoids grown in the field at Louisiana, USA is expected to be available to the public domain. Incorporation of genes for carotenogenesis in seeds by transgenesis or by introgression did not change any significant agronomic characteristics in rice plants. The ongoing and future study of bioavailability, quality, larger field testing and freedom to operate will ensure the benefit of Golden Rice to the people who need them most.     

Watermelon lycopene β-cyclase: promoter characterization leads to the development of a PCR marker for allelic selection

In the carotenoid biosynthetic pathway, lycopene β-cyclase (LCYB) catalyzes the cyclization that converts lycopene into β-carotene. Only a single copy of LCYB was identified and was suggested to encode a chromoplast-specific LCYB (CYCB type) in watermelon [Citrullus lanatus (Thunb.), Matsum & Nakai]. Splicing variants in the 5′-untranslated region were identified, but alternative splicing did not provide an explanation of the regulation of carotenoid accumulation in watermelon flesh. A quantitative assay using real time-PCR showed that differential expression was not detected between red- and canary yellow-fleshed watermelon cultivars. LCYB promoter regions were isolated and characterized, and a sequence difference was identified in the promoter region between red and canary yellow LCYB alleles. This polymorphism did not change the expression of LCYB, but does provide a reliable marker for discriminating LCYB alleles for red and canary yellow flesh. To develop a PCR-based marker to distinguish between the two LCYB alleles, we designed primers flanking the polymorphic region. The newly developed marker, designated Clcyb.600, co-segregated perfectly with flesh color phenotypes and single nucleotide polymorphism (SNP) markers developed in our previous study. Moreover, the Clcyb.600 marker offers easier discrimination of LCYB alleles than SNP or cleaved amplified polymorphic sequence markers, as it does not require restriction enzyme digestion for genotyping. Genotyping of LCYB promoter alleles in various commercial cultivars and plant introductions indicated that watermelon cultivars can be classified into two groups, those carrying a red LCYB allele or a canary yellow LCYB allele.     

甘薯块根类胡萝卜素与薯肉色的研究

甘薯块根类胡萝卜素的含量随品种不同有很大差异。高者达28.08毫克/100克鲜重,少者仅0.12毫克/100克鲜重。块根薯肉色与类胡萝卜素的含量呈正相关,r=0.82,达极显著水平。类胡萝卜素的组成成分也影响着块根的薯肉色。β-胡萝卜素是甘薯块根的主要色素,当其含量达总量60%以上,且类胡萝卜素的总量也高时,块根薯肉色橙红。用色差