Peroxidase Isoenzymes in Development of Tall and Dwarf Cultivars of Rice

Four cultivars of rice, Hansraj (tall), Jamuna, Padma and Sabarmati(all dwarf) were analysed for variation in isoperoxidase patternsduring development by horizontal starch-gell electrophoresis.The samples were taken at weekly intervals, starting with soakedseeds (12 h) until the post panicle stage. There is a distinctpattern of peroxidase isoenzymes in the tall and dwarf cultivarsstudied. Some isoenzymes appear at a particular developmentalstage while others disappear while some remain fairly constantonce they are activated. Hansraj showed more qualitative fluctuationsin peroxidase than did the three dwarf varieties. A few isoperoxidaseswere specific to some varieties such as bands A₃ and A₇ forHansraj and band A₄ for Sabarmati. These specific bands of peroxidasemay have some role to play in development of Hansraj (tall)and Sabarmati (with aroma). Besides this, greater fluctuationsin peroxidase activity in the tall variety may be due to loosecontrol in the regulation of peroxidase activity. The significanceof controlling elements of enzyme activity is discussed.     

Fertility in Crosses Involving Diploid and Autotetraploid Raspberries: I. The Embryo

Crosses between diploid raspberry cultivars (Rubus idaeus L.)and their autotetraploid forms have shown that embryo shapedepends on three main factors—the variety, the stage ofdevelopment reached before growth ceases, and the ploidy ofthe embryo itself. Embryo growth, however, depends on the abilityof the endosperm to nourish the embryo and so on the harmoniousco-existence of derivatives of the gametes which formed theendosperm. Crosses between plants of unequal ploidy produceendosperms which are unbalanced. In general, the order of fertilityof the crosses is 2n selfed, 4n selfed, 4n X 2n, 2n X 4n, andthis can be partly explained if the effect of chromosome doublingis to increase the genetic strength of the male gametes morethan that of the female. Variations in the embryo growth inthe 2n X 4n and 4n x 2n crosses are ascribed to smaller differencesin genetic strength between varieties and between the male andfemale gametes within a variety. Embryos derived from crosseswithin a single variety grew less well than those derived fromcrosses between varieties, other factors being equal, and thisis considered to be an early expression of inbreeding depressionin the embryo.     

菊属11个野生种和12个栽培品种遗传关系的ISSR分析

为进一步明确菊属野生种与栽培品种的遗传关系和多样性,本研究利用ISSR分子标记技术对菊属11个野生种和12个栽培品种之间的遗传关系进行比较分析.从75个ISSR引物中筛选出了14个引物,对供试材料的DNA进行扩增,共获得142条清晰可辨的谱带,多态位点比率为95.1%;菊属野生种的平均有效等位基因数(effective number of alleles,Ne)、平均Nei's基因多样性指数(Nei's gene diversity,H)及Shannon信息指数(shannon's information index,I)均高于栽培菊花,说明各野生种间基因差异比较显著,多态性强于栽培品种.UPGMA聚类结果表明:菊属野生种呈现由低倍向高倍进化的趋势;栽培菊花之间遗传关系复杂,大体可以推断出平瓣是菊花的基本瓣形;菊花脑与栽培菊花亲缘关系最近,小红菊、龙脑菊、若狭滨菊与栽培菊花关系亦较近,神农香菊与其它材料关系最远.本研究的结果表明菊属野生种与栽培品种之间遗传关系比较复杂,而ISSR分子标记技术可以较好地从分子水平上揭示出菊属植物间的遗传关系.     

Polyploidy creates higher diversity among Cynodon accessions as assessed by molecular markers

Developing a better understanding of associations among ploidy level, geographic distribution, and genetic diversity of Cynodon accessions could be beneficial to bermudagrass breeding programs, and would enhance our understanding of the evolutionary biology of this warm season grass species. This study was initiated to: (1) determine ploidy analysis of Cynodon accessions collected from Turkey, (2) investigate associations between ploidy level and diversity, (3) determine whether geographic and ploidy distribution are related to nuclear genome variation, and (4) correlate among four nuclear molecular marker systems for Cynodon accessions’ genetic analyses. One hundred and eighty-two Cynodon accessions collected in Turkey from an area south of the Taurus Mountains along the Mediterranean cost and ten known genotypes were genotyped using sequence related amplified polymorphism (SRAP), peroxidase gene polymorphism (POGP), inter-simple sequence repeat (ISSR), and random amplified polymorphic DNA (RAPD). The diploids, triploids, tetraploids, pentaploids, and hexaploids revealed by flow cytometry had a linear present band frequency of 0.36, 0.47, 0.49, 0.52, and 0.54, respectively. Regression analysis explained that quadratic relationship between ploidy level and band frequency was the most explanatory (r = 0.62, P < 0.001). The AMOVA results indicated that 91 and 94% of the total variation resided within ploidy level and provinces, respectively. The UPGMA analysis suggested that commercial bermudagrass cultivars only one-third of the available genetic variation. SRAP, POGP, ISSR, and RAPD markers differed in detecting relationships among the bermudagrass genotypes and rare alleles, suggesting more efficiency of combinatory analysis of molecular marker systems. Elucidating Cynodon accessions’ genetic structure can aid to enhance breeding programs and broaden genetic base of commercial cultivars. O. Gulsen and S. Sever-Mutlu contributed equally to this work.     

Embryogenesis and plant regeneration of pakchoi (Brassica rapa L. ssp. chinensis) via in vitro isolated microspore culture

Isolated microspores of various populations of three varieties of the Chinese cabbage pakchoi (Brassica rapa ssp. chinensis) were cultivated in vitro on NLN82 medium (Lichter 1982) and embryos and plantlets obtained with nine cultivars. The best embryo yield per bud was 57.4. A 33°C one day heat treatment was generally necessary to induce embryogenesis. Analysis of ploidy level through flow cytometry for two cultivars indicated that haploids were present.Abbreviations BA 6-benzylaminopurine - DAPI 4,6-diamidino-2-phenylindol - NAA naphthalene acetic acid - DH doubled haploid     

Peroxidase Activity in Leaves of Wheat Cultivars Differing in Resistance to Erysiphe graminis DC.

The peroxidase activities in leaves from resistant and susceptible cultivars of wheat infected and non-infected by Erysiphe graminis DC were studied. In non-infected wheat, soluble and ionic bound peroxidase activity level was found to be higher in the resistant cultivar than that in the one susceptible to Erysiphe graminis DC. After infecting wheat leaves with Erysiphe graminis DC a remarkable increase in the activity of soluble and ionic bound peroxidases was detected 5 days after inoculation only in the resistant cultivar. In the susceptible cultivar a high increase in the activity of the soluble and ionic bound peroxidases occurred only 15 days after inoculation. Using ion exchange chromatography four peroxidase fractions were obtained from infected susceptible and resistant cultivars as from non-infected ones. The fraction II in non-inoculated resistant cultivars was much higher than that in the susceptible one. This fraction increased after inoculation in both cases reaching a higher level in resistant cultivars. Fraction I was higher in the susceptible cultivar. Electrofocusing profiles of peroxidase from the susceptible and resistant cultivar differed from one another. New peroxidase bands after inoculation appeared only in the resistant cultivar.     

Factors Influencing Diversity of Farmers’ Varieties of Sweet Potato in Uganda: Implications for Conservation

Factors Influencing Diversity of Farmers’ Varieties of Sweet Potato in Uganda: Implications for Conservation. There is increasing concern that agricultural intensification is causing loss of crop biodiversity due to displacement of traditional farmers’ varieties by a small number of improved cultivars. Using ethnobotanical surveys, we assessed the implication of adoption of new sweet potato (Ipomoea batatas) cultivars on the maintenance of farmers’ varieties in Uganda. Other factors influencing varietal diversity were also assessed. A total of 102 farmer households distributed in the top three sweet potato production agro-ecological zones were interviewed. With the exception of released cultivars, very few varieties appeared in more than one region. The majority of the respondents indicated that they continue to plant some of the existing varieties when they adopt new cultivars. Loss of planting materials due to drought was a major constraint to maintaining varietal diversity for this vegetatively propagated crop. Limited land and lack of access to best management practices were also key constraints to maintenance of farmers’ varieties. The primary criteria for adopting new cultivars were higher yield, taste, and duration to maturity. Yield stability, tolerance to native biotic and abiotic stresses, and good taste were important for maintenance of currently grown varieties. Overall, criteria for variety selection varied with household characteristics including farmer age and gender, uses of the crop, micro-climatic conditions in the farmers’ fields, and level of access to agricultural extension. The observed heterogeneity in selection criteria, influence of social ties, and the role of environment in varietal maintenance have important implications for establishing breeding priorities and preservation of crop diversity.     

Salinity induced oxidative stress and antioxidant system in salt-tolerant and salt-sensitive cultivars of rice (Oryza sativa L.)

Indices of oxidative stress viz., superoxide radical and H₂O₂ content increased in leaves of all the cultivars with the rise in salinity level, the increase was more pronounced and significant in salt-sensitive varieties and non-significant in resistant cultivars. Except for glutathione reductase (GR), basal activities of all other antioxidative enzymes viz. superoxide dismutase (SOD), catalase (CAT), peroxidase (POX), ascorbate peroxidase (APX) and glutathione reductase (GR) were significantly higher in leaves of all the resistant cultivars as compared to the sensitive ones. A differential response of salinity was observed on various enzymatic and non-enzymatic components of antioxidant system in leaves of salt-tolerant and salt-sensitive cultivars of rice (Oryza sativa L.). Activities of superoxide dismutase and glutathione reductase enhanced in all the tolerant cultivar while declined in the sensitive cultivars with increasing salinity from 0 to 100 mM. Salt-stress induced the activities of catalase and peroxidase in all the cultivars but the magnitude of increase was more pronounced in the sensitive cultivars than in the tolerant cultivars. Contrarily, APX activity increased in the salt-sensitive cultivars but showed no significant change in the salt-tolerant cultivars. The amount of ascorbic acid content, reduced glutathione (GSH), reduced/oxidized glutathione (GSSG) ratio was higher in leaves of the tolerant cultivars than that of the sensitive cultivars under saline conditions. It is inferred that leaves of salt-tolerant cultivars tend to attain greater capacity to perform reactions of antioxidative pathway under saline conditions to combat salinity-induced oxidative stress.     

Genetic Diversity and Variation Among Botanical Varieties of Old Portuguese Wheat Cultivars Revealed by ISSR Assays

Inter-simple sequence repeats (ISSRs) were used for genetic diversity analyses of an Old Portuguese wheat collection. Eighteen primers produced 96.3 and 98.5% of ISSR polymorphism in bread and durum wheat cultivars, respectively. The unweighted pair group method with arithmetical averages (UPGMA) phenogram clearly split all cultivars based on their species/ploidy, reflecting a defined genetic structure. ISSRs revealed high genetic diversity at interspecific, intraspecific, and intercultivar levels. Thirty-three exclusive ISSR markers were found. Cultivars were clustered according to their botanical varieties and, in a few cases, with their homonym(s). No statistically significant differences were found between genetic diversity parameters of durum and bread wheat, probably due to high intraspecific diversity. Similar analyses were performed among botanical varieties, and their relationships were defined. Cladograms resembled UPGMA clustering. This highly genetically diverse Old wheat collection will be conserved and maintained, and it could be further used in breeding programs to widen the narrow genetic basis of modern wheat varieties and to avoid the loss of rare and unique alleles.     

Elicitation of peroxidase activity and lignin biosynthesis in pepper suspension cells by Phytophthora capsici

Cell suspension cultures of three varieties of Capsicum annuum L., each with a different degree of sensitivity to the fungus Phytophthora capsici, responded to elicitation by both lyophilized mycelium and fungus filtrate with a hypersensitive reaction. They showed the synthesis or accumulation of PR-proteins with peroxidase (EC 1.11.1.7) activity and the accumulation of lignin-like polymer (as measured by derivatization with thioglycolic acid). The cultivation medium was optimised for both plant and fungus growth in order to avoid any stress during their combination. The resistant pepper variety, Smith-5, showed a more intense response to the elicitor preparations than the sensitive varieties, Americano and Yolo Wonder. This was particularly evident when the cell suspensions were elicited with the filtrate. After elicitation, the cell walls thickened through the accumulation of lignin, as can be observed by staining microscope preparations with methylene blue. Elicitation also reduced the level of total peroxidase activity in the susceptible varieties, while such activity increased in resistant varieties, and was accompanied by de novo expression of acidic peroxidase isoenzymes in the extracellular and cell wall fractions. Of note was the PR protein of pI 5.7 showing peroxidase activity, which was induced by both elicitor types in the elicited cell suspensions of the resistant variety alone, making it a marker of resistance. The increases in the activity of these peroxidases in the resistant variety are in concordance with the accumulation of lignin observed 24 h after inoculation by both elicitors from the fungus. The possible role of these isoenzymes in lignin biosynthesis, used to reinforce the cell walls against fungal penetration of the cells, is discussed. These results are in accordance with those previously observed in plant stem sections.     

A Comparison of Stem Peroxidases in Bush and Vine Forms of Squash (Cucurbita maxima Duch.and C. pepo L.)

Total peroxidase activities and peroxidase isozymes were comparedamong 10 bush- and vine-squash cultivars of Cucurbita maximaDuch. and C. pepo (L.) Several qualitative variations of isozymeswere detected between C. maxima and C. pepo, and some differenceswere evident among varieties of C. pepo. There were no qualitativedifferences between genetically similar bush and vine strains.Quantitative differences were difficult to resolve, althoughit did appear that in varieties of C. maxima exhibiting lowlevels of peroxidase activity, isozymes C₃, C₄, and C₆ wereless intense. Depending upon the cultivars compared, total peroxidase activityin bush forms was either higher or lower than, or the same astheir vine counterparts. Since the major bush genes in the varietiesstudied are believed to be allelic, the results indicate thatthe over-all genotype of squash varieties can influence therelative expression of peroxidase activity between bush andvine forms.     

Responses to drought induced oxidative stress in five finger millet varieties differing in their geographical distribution

The study presents the impact of drought stress on five finger millet varieties (PR202, VL146, VL315, PES400 and VR708), representing contrasting areas of Indian sub-continent. Drought stress induced increase in the activity of superoxide dismutase, ascorbate peroxidase and glutathione reductase was higher in PR202 and VL315, while the activity was lower in the varieties PES400 and VR708. Ascorbate peroxidase : superoxide dismutase ratio, which is a crucial factor in alleviating drought stress, was higher in varieties PR202 and VL315, whilst the varieties PES400 and VR708 exhibited a lower ratio under stress. The variety PES400 recorded maximum stress induced damage, as indicated by higher accumulation of malondialdehyde and hydrogen peroxide; whereas the variety PR202 recorded least stress induced cytotoxic damage. The results clearly indicate that better drought tolerance of the variety PR202 is positively related to the capacity of its antioxidant system to scavenge reactive oxygen species, resulting in a reduced incidence of oxidative damage. Ascorbate peroxidase : superoxide dismutase ratio is found to be a critical factor governing the stress tolerance potential of different varieties. Therefore, varieties PR202 and VL315 were found to be tolerant while PES400 was susceptible to drought stress.     

Evaluation of salinity tolerance in sorghum (<Emphasis Type="Italic">Sorghum bicolor</Emphasis> L.) using ion accumulation,proline and peroxidase criteria

Salt tolerance of sorghum varieties in terms of fresh weight, ion accumulations, proline content and peroxidase activity was analyzed in this study. Three sorghum varieties, Payam, Kimia, and Jambo, differing in salt tolerance, were grown in a greenhouse-hydroponic culture with a complete nutrition solution to which 0, 50, 100, 150 and 200 mM NaCl was added. Plant roots and leaves were harvested at 15 and 30 days after treatment and subjected to analysis. Clear decline in K⁺ and Ca²⁺ concentrations and increase in Na⁺ and proline contents were observed in the root and leaf tissues at each NaCl concentration in all varieties during the NaCl treatment. The Ca²⁺ concentration in leaves was higher than in roots, and had the following order in the tested cultivars: Jambo, Kimia, and Payam. Total peroxidase activity increased under salinity stress and it was proportional with the salt concentration. Payam had the largest decrease (46.95%) in fresh weight caused by NaCl, while Jambo had the lowest decrease, 28.63%. Linear regression analysis revealed significant relationships between the estimated factors and fresh weight. The profiles of isoperoxidases were modified under stress conditions. Two isoforms, A1 and A2, were detected in all three varieties with different intensities. Under NaCl stress, isoperoxidases were strongly expressed and a third isoform, A3, was specifically found in variety Jambo suggesting that A3 is implicated in salt adaptation of this variety.     

RAPD discrimination of Agaricus bisporus mushroom cultivars

Cultivars of the white button mushroom Agaricus bisporus are difficult to differentiate, which has made strain protection problematic for this crop species. We have used RAPDs to discriminate between 26 strains of A. bisporus, 24 of which were commercial cultivars, and to characterise the genetic relatedness of these strains. Using 20 primers, 211 RAPD markers were identified and used in hierarchical cluster, patristic distance and parsimony analyses. All strains could be differentiated using the aggregated primer data. Although no one primer could differentiate all 26 strains, several individual primers yielded unique fingerprints for a variety of strains. The greatest differences (up to 28% variation) were observed in comparisons with or between two wild collections of A. bisporus. Quondam cultivars, commercial brown and off-white varieties proved more variable than the widely grown 'hybrid' types. Of the 15 hybrid varieties analysed, only one differed substantially (20% or more variable). The patristic and parsimony analyses both demonstrated the gross similarity of the hybrids, many of which appear to be essentially derived varieties from two original hybrid cultivars. RAPD analyses can assist mushroom strain identification and could play a role in the protection of novel cultivars.     

Analysis of genetic diversity and population structure within Florida coconut (<Emphasis Type="Italic">Cocos nucifera</Emphasis> L.) germplasm using microsatellite DNA,with special emphasis on the Fiji Dwarf cultivar

Using 15 simple sequence repeat (SSR) microsatellite DNA loci, we analyzed genetic variation within Cocos nucifera germplasm collections at two locations in south Florida, representing eight cultivars. The loci were also used in a parentage analysis of progeny of the 'Fiji Dwarf' variety at both locations. A total of 67 alleles were detected, with eight the highest number at any one locus. These loci identified 83 of the 110 individual palms. Gene diversity of the 15 loci ranged from 0.778 to 0.223, with a mean of 0.574. 'Fiji Dwarf', 'Malayan Dwarf', 'Green Ni?o' and 'Red Spicata' cultivars resolve as distinct clusters in a neighbor joining tree using modified Rogers distance, while the tall varieties form two aggregates. The highest gene diversity was found in the tall cultivars (H = 0.583 cumulatively), and the lowest in the 'Malayan Dwarf' (H = 0.202). After the tall coconuts, the 'Fiji Dwarf' was most genetically diverse (H = 0.436), and had the largest number of unique alleles. Genetic identity is highest among the 'Malayan Dwarf' phenotypes, and between the tall varieties. The 'Red Malayan Dwarf' is genetically distinct from the 'Green' and 'Yellow Malayan Dwarf' phenotypes, which cannot be distinguished with the SSR loci used. Off-type 'Malayan Dwarf' phenotypes (putative hybrids with talls) can be identified genotypically. Parentage analyses of 30 'Fiji Dwarf' progeny propagated from five adults surrounded by other cultivars estimate that only 20% of the progeny were out-crossed to the other varieties, while 40-46% were possible selfs. This suggests that a seed-production orchard of the variety maintained at reasonable distance from other varieties, will likely yield only 'Fiji Dwarf' genotypes. Our data are discussed in the context of hypotheses of coconut dissemination around the world.     

SSR标记鉴定浙江省主要无性系茶树品种的研究

为促进浙江省茶树育种的发展,利用SSR引物对浙江省茶树育成品种的遗传多样性进行了研究,筛选出可用于鉴别浙江省茶树品种的核心鉴定引物和标准品种,并进一步应用于未知茶苗身份鉴定。首先,利用35对SSR引物研究了36个茶树育成品种,并进行聚类分析;然后,根据电泳谱带和基因型筛选出核心鉴定引物和标准品种;最后,对4株未知茶苗进行了身份鉴定。结果表明:共有34对引物表现出多态性,各品种基本按遗传背景聚类,重复样本间遗传距离介于0~0.094;有10对引物确定为核心鉴定引物,8个品种为标准品种;4株未知身份茶苗中,NH-01属于乌牛早品种,另外3株并非浙江现有品种。本研究认为,核心鉴定引物在两个浙江育成品种间差异引物对≥2时,应判定为不同品种;差异引物对≤1时,应判定为相同品种或极相似品种,必要时应引入其余24对引物计算遗传距离进一步验证,遗传距离>0.140判定为不同品种,遗传距离≤0.140判定为同一品种。     

利用流式细胞光度术鉴定苹果倍性的研究

利用流式细胞光度术测定了苹果１２个二倍体,５个三倍体细胞ＤＮＡ含量。结果表明：二倍体细胞核ＤＮＡ含量平均为２．２７ｐｇ,三倍体细胞核ＤＮＡ含量平均为３．１３ｐｇ。     

Cyclopiazonic acid production byPenicillium griseofulvum in relation to different cultivars of maize

The reaction of 15 varieties of maize to the growth and cyclopiazonic acid (CPA) production ofPenicillium griseofulvum was examined as a means of identifying varieties which would be resistant to this infestation. Only one variety, MMEH-25, was resistant to the fungus, seeds containing little CPA 30 days after infestation. This variety and Ganga-5, which was only moderately resistant, are popular commercial cultivars.     

中国大蒜(Allium sativumL.)18个品种的酯酶同工酶多态性分析

采用聚丙烯酰胺凝胶电泳(PAGE)分离了中国大蒜3个生态型（低温反应敏感型、低温反应中间型和低温反应迟钝型）中18个较典型的品种的酯酶同工酶,并用排序分析法对18个品种的亲缘关系进行了分析,将18个品种分为3个变种群: 1.“苏联”蒜变种群(var.Russia),2.吉木萨尔白皮蒜变种群(var.Jimusaer),3.中国内陆大蒜变种群(var.China)。其中中国内陆大蒜变种群又可分为5个品种群：①关中蒜品种群,②西北蒜品种群,③西南蒜品种群,④云贵蒜品种群,⑤华东蒜品种群。实验结果初步证实,大蒜生态型不能完全等同于基因型,酯酶同工酶的变化可能更能说明大蒜的亲缘进化关系。     

Temporary chromosome number stabilization in potato cell cultures

Cell cultures of Solanum chacoense (monohaploid) and Solanum tuberosum (tetraploid cultivars and parthenogenetically derived dihaploid clones) were found to be highly mixoploid.Relative stabilization of chromosome number at the ploidy level of the original plant material was achieved in microcalli obtained from single cells or small cell colonies (up to about 5 cells) of stock callus lines. This relative stabilization was maintained over three subcultures, which is sufficient for selection procedures. It has been shown that the stabilization can be maintained during a number of further subcultures. Division centers were repeatedly observed in calli characterized by high mitotic activity. As has been shown for the first time there exist significant differences in the ploidy levels of several division centers within one and the same callus. This is of particular importance to callus subculture.