Molecular evaluation of genetic variability in wild populations of mulberry (Morus serrata Roxb.)

Sixteen populations of the wild mulberry, Morus serrata Roxb., were analysed for their genetic diversity with the aim of using them in introgressive breeding programmes with cultivated relatives. Five genets from each population were collected from different natural populations of M. serrata present in Uttaranchal and Himachal Pradesh in India, and diversity of morpho‐anatomical traits and inter‐simple sequence repeat (ISSR) markers were studied. Significant amounts of genetic diversity were observed among these populations for morpho‐anatomical as well as DNA markers. The 17 ISSR primers generated a total of 95 DNA markers, 51 of which were polymorphic, revealing 67% polymorphism among the populations. The pair‐wise genetic distance, estimated from these DNA markers varied from 0.091 between Urgam‐3 and Kathpuria to 0.258 between Dakrakao‐1 and Dunda with an average genetic distance of 0.165. Clustering analysis grouped these 16 populations into three broad groups. The grouping showed a moderate correlation with the geographical distances. Based on the morphological traits and molecular genetic variability, plants of Urgam‐1, Bhowali farm, Nainitikar, Dunda or Korwa‐2 can be selected for breeding and conservation programmes.     

23个广西本地芒果品种的ISSR分析

本研究对23个分别来自广西本地品种或广西选育的品种进行了SSR分析,并用15个芒果栽培品种印度（4个品种）、美国（3个品种）、缅甸（3个品种）、泰国（2个品种）及菲律宾、巴基斯坦和斯里兰卡（各1个品种）和2个芒果近源种冬芒（1个）和扁桃（1个）作为参照.从42个ISSR引物中筛选出9个多态性好的引物构建DNA指纹图谱来鉴别芒果的基因型.根据这9个引物获得的电泳图谱结果表明,本研究中所有供试品种能互相区分开来并表现出丰富的遗传多样性,说明ISSR是一种鉴定芒果品种（系）非常有效的方法.用74条多态性条带聚类分析作图发现所有供试的广西品种与秋芒、马切苏芒、象牙芒和爱文芒归为一个大类,而且广西本地芒果品种之间的亲缘关系较近.     

Root traits and yield in sugar beet: identification of AFLP markers associated with root elongation rate

Morpho-physiological and molecular analysis were conducted to identify useful root indexes of sugar beet nutrient uptake capacity and productivity. Root architectural parameters, root elongation rate, sulfate uptake rate and glucose and fructose content in the root apex, traits involved in the plant response to sulfate stress, were evaluated in 18 sugar beet genotypes characterized by different root yield. Morpho-physiological traits, determined on 11-day-old seedlings grown in hydroponics under sulfate deprivation, showed variations from 59 to 197% and were significantly correlated (P < 0.01) with root yield. Under field conditions, the highest root yield genotype (L18), which has the highest root phenotypic values following sulfate shortage, also showed the greatest root length density and leaf relative water content, with respect to the lowest root yield genotype (L01). Bulk segregant analysis based on AFLP analysis, done on a segregating progeny obtained from the cross between the two lines L01 × L18, allowed the identification of two AFLP markers associated to the root elongation rate parameter that showed the highest variation among all the analyzed root traits. The genetic diversity of root adaptive traits and the use of marker-assisted selection aimed at increasing sugar yield under water and nutrient stress in sugar beet breeding programmes are discussed.     

Leaf yield component combining abilities in mulberry (Morus spp.)

A line × tester analysis was carried out in mulberry (Morus spp.) to determine the genetic interaction in the expression of various quantitative characters including leaf yield. Eight clonal varieties were selected, 3 of them were designated as lines (♀) viz. Berhampore-1, China white and MS-5 and 5 of them were called as testers (♂) viz. Mandalaya, Kosen, Assamjati, MS-1 and Kajli. Combining ability studies were conducted on these parents along with their F₁ hybrids for the variables laminar index, growth rate, weight of 100 dry leaves, number of primary branches per plant, plant height, nodal distance, leaf-twig ratio, aerial biomass, moisture content, moisture retention capacity and leaf yield. Broad genetic variability was observed among the genotypes. The ratio of General Combining Ability (GCA) and Specific Combining Ability (SCA) indicated the predominance of non-additive genes in mulberry. While China white (female) and MS-1 (male) were the best general combiners among the parents, Berhampore-1 × Kajli was the best cross for leaf yield. Results suggest that selective crossing followed by proper screening may be the best approach for breeding of high yielding varieties in mulberry. This revised version was published online in July 2006 with corrections to the Cover Date.     

Application of ISSR markers in the genus Lycopersicon

The level of polymorphism in tomato was studied using ISSR-PCR. Five tomato species: Lycopersicon esculentum, Lycopersicon pennellii, Lycopersicon cheesmanii, Lycopersicon humboldtii, Lycopersicon hirsutum and two Lycopersicon esculentum substitution lines IL 6-3 and WSL 6 were analyzed. ISSR-PCR was performed with fourteen primers. Nine of these fourteen primers were individually able to distinguish all tomato species. The data were used to create a phylogenetic tree of the five tomato species. The tree showed complete correspondence to previous phylogenetic investigations. ISSR-PCR on two Lycopersicon esculentum substitution lines IL 6-3 and WSL 6 enabled us to place thirteen ISSR markers on the classical map of Lycopersicon esculentum chromosome 6. Some of the markers were not located in the pericentromeric region. Using one ISSR and one RGA (Resistance-gene analogs) primer resulted in fingerprints having some new bands compared with ISSR fingerprints. This revised version was published online in August 2006 with corrections to the Cover Date.     

应用ISSR分子标记绘制红麻种质资源DNA指纹图谱

以6份红麻种质资源为材料, 对UBC807~UBC80等80个ISSR引物进行筛选, 筛选出多态性好的ISSR引物20个。利用这20个ISSR引物扩增来自国内外84份红麻种质资源, 共获得230条谱带, 平均每个引物扩增出11.5条谱带, 其中多态性谱带185条, 多态性条带比率为80.43%, 表明供试的红麻种质资源遗传多样性较丰富。以供试84份红麻种质资源的ISSR扩增谱带为基础, 建立了供试材料扩增条带指纹数据库的Excel文件。根据指纹图谱唯一性原则, 采用自行开发的DNA指纹数据分析软件, 再从20个多态性好的ISSR引物中遴选出UBC 813、UBC 825、UBC 836、UBC 888和UBC 889引物, 绘制出82个红麻种质资源的DNA指纹图谱, 为红麻种质资源分子身份证的构建奠定了基础。     

Comparison of two crossing and four selection schemes for yield, yield traits, and slow rusting resistance to leaf rust in wheat

The most important breeding objectives in crop improvement are improving grain yield, grain quality, and resistances to various biotic and abiotic stresses. The objectives of our study were to compare two crossing and four selection schemes for grain yield, yield traits, and slow rusting resistance to leaf rust (Puccinia recondita) based on additive genes in wheat (Triticum aestivum), and to identify the most efficient crossing and selection methodologies in terms of genetic gains and cost efficiency. Segregating populations were derived from 18 simple crosses and the same number of top (three-way) crosses. Half of the crosses were derived from Yecora 70 and the other half from Veery #10 as the common leaf rust susceptible parents. The four selection schemes were: pedigree, modified bulk (F₂ and F₁-top as pedigree, selected lines in F₃, F₄, F₂-top, F₃-top as bulk; and pedigree in F₅ and F₄-top populations), selected bulk (selected plants in F₂, F₃, F₄, F₁-top, F₂-top and F₃-top as bulk; and pedigree in F₅ and F₄-top populations), and nonselected bulk (bulk in F₂, F₃, F₄, F₁-top, F₂-top and F₃-top; and pedigree in F₅ and F₄-top populations). A total of 320 progeny lines, parents and checks were tested for grain yield, other agronomic traits and leaf rust resistance during the 1992/93 and 1993/94 seasons in Ciudad Obregon (Sonora State, Mexico) which represents a typical high yielding irrigated site. The influence of the type of cross and the selection scheme on the mean grain yield and other traits of the progenies was minimal. The selection of parents was the most important feature in imparting yield potential and other favourable agronomic traits. Moreover, the highest yielding lines were distributed equally. Progeny lines derived from Veery #10 crosses had significantly higher mean grain yield compared to those derived from the Yecora 70 crosses. Furthermore, a large proportion of the highest yielding lines also originated from Veery #10 crosses. Mean leaf rust severity of the top cross progenies was lower than that of the simple cross progenies possibly because two parents contributed resistance to top cross progenies. Mean leaf rust severity of the nonselected bulk derivatives was twice that of lines derived from the other three schemes. Selected bulk appears to be the most attractive selection scheme in terms of genetic gains and cost efficiency. This revised version was published online in August 2006 with corrections to the Cover Date.     

Genome mapping and molecular markers identification for yield,yield component and fibre quality traits in tetraploid cotton

The identification of quantitative trait loci (QTL) across different environments is a prerequisite for marker‐assisted selection (MAS) in crop improvement programmes. CottonSNP63k Illumina infinium array was used for genotyping 178 inter‐specific recombinant inbred lines and the parents, and identified 1,667 homozygous polymorphic markers between the parents. Of these, 1,430 markers were used for the construction of linkage map after removing 237 redundant markers. The genetic map spans a total genetic length of 3,149.8 cM with an average marker interval size of 2.2 cM. The phenotypic data from five environments were analysed separately using inclusive composite interval mapping which identified a total of 56 QTL explaining phenotypic variances (PVE) in the range of 8.18%–28.91%. There were 11 and 24 major QTL found for fibre quality and yield components, respectively. A total of 64 QTL were identified through Multi‐Environment Trials analysis, of which 34 recorded QTL × Environment interactions.     

Molecular markers for yield components in Brassica juncea – do these assist in breeding for high seed yield?

A population of 112 F₁-derived doubled haploid lines was produced from a reciprocal cross of Brassica juncea. The parents differed for seed quality, seed color and many agronomic traits. A detailed RFLP linkage map of this population, comprising 316 loci, had been constructed, and was used to map quantitative trait loci (QTL) for seed yield and yield components, viz. siliqua length, number of seeds per siliqua, number of siliques per main raceme and 1000-seed weight. Stable and significant QTLs were identified for all these yield components except seed yield. For yield components, a selection index based on combined phenotypic and molecular data (QTL effects) could double up the efficiency of selection compared to the expected genetic advance by phenotypic selection. Selection indices for high seed yield, based on the phenotypic data of yield and yield components, could only improve the efficiency of selection by 4% of the genetic advance that can be expected from direct phenotypic selection for yield alone. Inclusion of molecular data together with the phenotypic data of yield components in the selection indices did not improve the efficiency of selection for higher seed yield. This is probably due to often negative relationships among the yield components. Most of the QTLs for yield components were compensating each other, probably due to linkage, pleiotropy or developmentally induced relationships among them. The breeding strategy for B. juncea and challenges to marker assisted selection are discussed.     

ISSR profiling of Indian cultivars of mulberry (Morus spp.) and its relevance to breeding programs

Mulberry, Morus spp. has a wide range of use, the chief among them is to feed the silk producing caterpillar Bombyx mori L. (Bombycidae; Bombycoidea). As a homeland of mulberry, India has a number of indigenous mulberry species, of which a few are widely cultivated. In the present investigation genetic distance among such eleven mulberry cultivars originated from six different states of India covering a wide geographic area extending from 15^° N to 32^° N latitude and 72^°E to 89^°E longitude was studied using inter-simple sequence repeat primers. Out of the 20primers tested, 13 primers, viz, nine di-nucleotide, three tri-nucleotide and one penta-nucleotide repeats, gave clear and reproducible band profiles. While the (AT)_n rich primers could not amplify the DNA, the (GA)n, (AC)n and (AG)n rich primers gave excellent amplification profiles. The genetic distance among the cultivars varied from a minimum of 0.053, between Punjab local and Bombay local, to a maximum of 0.431, between Almora local andSujanpur-5. Clustering of the cultivars according to nearest neighbor method created three groups. The north-Indian cultivars made a separate and distinct group while the cultivars originated from eastern and southern India occupied a distinct position. Almora local was found quite different from others. The first two canonical functions identified through discriminant function analysis accounted for 91.2% of the total variability. Distribution of cultivars belonging to six different zones on canonical matrix realized from Discriminant Function Analysis (DFA) revealed wider variability for West Bengal, Karnataka and Punjab which reaches the group centroids of Uttar Pradesh and Himachal Pradesh. This attests to the past contribution of West Bengal in east and Karnataka in south towards development of mulberry cultivars indifferent parts of India. Step-wise linear regression analysis, further, identified two markers (825.₁₄₀₀ and835.₇₅₀) associated with leaf yield, which also satisfied the Beta estimation, thereby testifying strong association of these two markers with leaf yield. This finding along with the classification of the eleven cultivars bear strong relevance to mulberry breeding for different agro climatic areas. This revised version was published online in August 2006 with corrections to the Cover Date.     

Molecular mapping of quantitative trait loci for plant growth, yield and yield related traits across three diverse locations in a doubled haploid rice population

A doubled haploid (DH) population of 125lines derived from IR64 × Azucena, an indica – japonica cross were grown in three different locations in India during the wet season of 1995. The parents of mapping population had diverse phenotypic values for the eleven traits observed. The DH lines exhibited considerable amount of variation for all the traits. Transgressive segregants were observed. Interval analysis with threshold LOD > 3.00 detected a total of thirty four quantitative trait loci (QTL) for eleven traits across three locations. The maximum number of twenty QTL were detected at Punjab location of North India. A total of seven QTL were identified for panicle length followed by six QTL for plant height. Eight QTL were identified on three chromosomes which were common across locations. A maximum of seven QTL were identified for panicle length with the peak LOD score of 6.01 and variance of 26.80%. The major QTL for plant height was located on Chromosome 1 with peak LOD score of 16.06 flanked by RZ730-RZ801 markers. Plant height had the maximum number of common QTL across environment at the same marker interval. One QTL was identified for grain yield per plant and four QTL for thousand grain weight. Clustering of QTL for different traits at the same marker intervals was observed for plant height, panicle exsertion, panicle number, panicle length and biomass production. This suggests that pleiotropism and or tight linkage of different traits could be the plausible reason for the congruence of several QTL. Common QTL identified across locations and environment provide an excellent opportunity for selecting stable chromosomal regions contributing to yield and yield components to develop QTL introgressed lines that can be deployed in rice breeding program. This revised version was published online in July 2006 with corrections to the Cover Date.     

树莓基因组DNA的提取及ISSR反应体系的正交优化

摘 要：以树莓优良野生种质插田泡（Rubus coreanus）为材料,比较了SDS法、CTAB法和改良CTAB法提取树莓基因组DNA的效果,结果发现三种方法均能提取到树莓DNA,但改良CTAB法优于CTAB法和SDS法,其所得的DNA质量最好,杂质最少。通过正交试验设计,对Taq酶,primer,dNTP和DNA用量进行了筛选,建立了树莓ISSR技术最优反应体系,即25 μl反应体系中含有1×PCR Buffer,2 mmol/L Mg2+,1.5 U Taq酶,0.2 μmol/L primer,0.4 mmol/L dNTP和20 ng DNA。采用引物UBC835和UBC873分别对10个树莓品种和8个树莓野生资源进行检验发现,该体系工作效果良好。     

Genetic gain in yield and changes associated with physiological traits in Brazilian wheat during the 20th century

The objective of this study was to characterize physiologically wheat cultivars released in different decades and identify selection criteria for the continued genetic progress in Brazil. Ten cultivars released from 1940 up to 2009 were tested during 2010 and 2011 crop seasons. The following traits were evaluated: grain yield (GY), thousand-kernel weight (TKW), grain number per m⁻² (GN), plant height (PH), harvest index (HI), above-ground biomass (BIO), relative Chlorophyll content and leaf gas exchanges. The increase in grain yield was 29 kg ha⁻¹ yr⁻¹ a genetic gain of 0.92%, annually. Grain yield improvement was largely associated with HI (0.94^**), number of grains m⁻² (0.93^**), BIO (0.88^**) and reduced PH (−0.93^**). The post-anthesis Chlorophyll content, stomatal conductance and pre/post-anthesis photosynthetic rate were positively correlated with GY. Genetic gains of Brazilian wheat are mainly related to the increases of HI, GN, and BIO. These improvements were achieved by reducing PH and raising gas exchanges and chlorophyll content.     

黄麻SSR标记与纤维产量性状的相关性

Simple sequence repeat (SSR) markers correlated to fiber yield traits would be a beneficial tool for molecular marker-assisted breeding in jute. In this study, 397 SSR markers were screened from 311 jute germplasms by the phenotype identification from 2016 to 2018 and 116 pairs of primers. The correlation analysis between SSR markers and fiber yield related traits by SPSS revealed that the range of the coefficient of variation related to 9 fiber traits was from 13.05% to 76.78%, indicating a comprehensive genetic variation. The correlation analysis of the agronomic traits showed that there were significantly correlations among these traits. The average correlation coefficient between branch height and nodes of main stem was the highest (r = 0.931), followed by the correlation coefficients (r = 0.781) of fresh bark weight per plant and fresh stem weight per plant and the coefficients (r = 0.779) of dry bark weight and fresh bark weight per plant. Analysis of variance (ANOVA) showed that the traits of main stem nodes, number of branches, plant height and branch height were relatively stable in different years with the higher broad heritability capacity. Furthermore, the SSR markers associated with fiber yield related traits were identified by Pearson correlation method. Stepwise regression analysis among each trait associated SSR markers indicated that there were six markers associated significantly with fiber yield related traits, and phenotypic variation explained by each SSR marker varied from 3.9% to 22.5%. These results will accelerate the development of molecular design breeding in jute.     

Construction of a genetic map of melon with molecular markers and horticultural traits, and localization of genes associated with ZYMV resistance

Abstract: A partial linkage map of melon was constructed from a cross between PI414723 and Dulce. Twenty-two SSR, 46RAPD, 2 ISSR markers and four horticultural markers [female flower form (a), Fusarium resistance, striped epicarp (st), and fruit flesh pH (pH)] were analyzed in an F₂/F₃ population to produce a map spanning 14 linkage groups. We report for the first time map positions for the st, a, and pH genes. One SSR marker was tightly linked to pH. Mapping the a gene for the female flower form to molecular linkage group 4 enabled the merging of the map of horticultural traits with the of molecular markers in this region. Using the 22 SSR markers of this map, two of the three postulated ZYMV resistance genes were located using a BC₁ population (PI414723 recurrent parent). One SSR marker was tightly linked to a ZYMV resistance gene, designated Zym-1. This revised version was published online in August 2006 with corrections to the Cover Date.     

砂仁及其混伪品益智仁的ISSR分子鉴别

为创建砂仁及其主要混伪品益智仁的ISSR分子鉴别方法,以UBC818为引物,对影响ISSR-PCR反应体系的引物、dNTPs、DNA模板、Taq DNA聚合酶和Mg2+浓度进行5因素4水平正交优化试验,并在此基础上筛选阳春砂ISSR引物及砂仁正伪品的鉴别引物.结果表明,20 μL阳春砂ISSR-PCR最佳反应体系包括引...     

Late‐season photosynthetic rate and senescence were associated with grain yield in winter wheat of diverse origins

There is a lack of studies that have investigated grain yield, its components and photosynthesis in late stages of wheat growth, giving us insufficient understanding of how these factors interact to contribute to yield during this period. As a result, three field experiments were carried out examining 20 winter wheat genotypes of diverse origins under irrigated, terminal drought and dryland conditions in the southern Idaho. Our objective was to evaluate the interaction between post‐anthesis physiological traits, especially leaf‐level photosynthetic capacity, senescence and yield components on grain yield in different moisture regimes. Genotype differences were found in leaf‐level photosynthesis and senescence, canopy temperature depression, grain yield and yield components in each water regime. Grain yield was closely associated with traits related to grain numbers. In all three moisture regimes, positive correlations were observed between grain yield and photosynthesis that were dependent on the timing or physiological growth stage of the photosynthetic measurement: highly significant correlations were found in the mid‐ and late grain filling stages, but no correlations at anthesis. Consistent with these findings, flag leaf senescence at the late grain filling stage was negatively correlated with grain yield and photosynthetic rate (under terminal drought and dryland conditions). These findings provided evidence that grain yield was sink‐limited until the final stages of growth, at which time sustained photosynthesis and delayed senescence were critical in filling grain. Because the trends were consistent in moisture sufficient and deficient conditions, the results suggest that late‐season photosynthesis and delayed leaf senescence are driven by the size of the reproductive carbon sink, which was largely governed by factors affecting grain numbers.     

Genetic improvement in wheat yield and associated traits. A re-examination of previous results and the latest trends

Two field experiments were carried out with seven wheat cultivars (three of them, including a commercial hybrid, released during the last 10 years) representing different eras of plant breeding, to evaluate genetic improvement over the last century in grain yield, height, biomass, harvest index and grain yield components. Plots were fertilized and irrigated, and lodging and diseases were prevented. Main culm height was negatively correlated with the year of release of the cultivars, probably as a consequence of selection for increased lodging resistance. There was no significant association between total above-ground biomass and year of release of the cultivars. On the other hand, grain yield increased as newer cultivars were released. Results indicate that during recent years harvest index has been kept as the main attribute responsible for increases in grain yield. In general, number of grains/m² was associated with increases in grain yield during the century. However, the newest cultivars showed an increased grain weight. In both growing seasons, cultivars released before 1980 showed a trend towards reduced grain weight, but cultivars released after 1987 had a similar number of grains per m² with a higher grain weight than their predecessors. This was probably because the most modern cultivars have a longer grain-filling duration with a similar length of growth cycle.     

Fast and reliable strawberry cultivar identification using inter simple sequence repeat (ISSR) amplification

ISSR amplification was evaluated for its applicability to strawberry varietalidentification. Eighteen primers based on various di- tri- or tetra- SSR motifswith 3 or 0 5'-selective nucleotides for anchoring were screened against thestrawberry genome by agarose gel electrophoresis. PCR conditions wereoptimised to obtain high quality patterns. Five primers that gave informativepatterns were selected and used to characterise, by polyacrylamide gelelectrophoresis, 30 strawberry varieties of various geographic and geneticorigins. A total of 390 bands, 113 of which were polymorphic (30%),were generated using these five primers. Genetic similarity between varietieswas estimated using Jaccard's coefficient of similarity. The associationsbetween varieties revealed by UPGMA analysis were consistent withpedigree data. With only one primer, all the varieties were distinguishedincluding those with a common pedigree. Banding patterns were highlyreproducible for DNA samples extracted from different tissues (leaves,sepals, and rhizomes) of the same plant, or from different plants (clones)of the same variety. ISSR technique is therefore a potentially useful tool forthe identification of strawberry varieties because it is simple, fast,cost-effective, highly discriminant and highly reliable.     

烟草SRAP和ISSR分子遗传连锁图谱构建

采用烤烟品种台烟7号与白肋烟品种白肋21杂交,构建了187个单株的F₂遗传作图群体,利用所筛选的68个能扩增出多态性条带的SRAP和ISSR引物,对F₂作图群体进行PCR扩增和遗传连锁分析,初步构建了一张包含26个连锁群、112个(92个SRAP和20个ISSR)标记位点的烟草遗传连锁图谱。该图谱覆盖长度为1 560.2 cM,平均图距18.1 cM。有16个标记未进入连锁群。26个连锁群包含2~20标记不等,连锁群遗传距离0~291.0 cM。连锁群上有24.1%的标记出现偏分离,主要集中在LG1和LG4连锁群上,其余分散在不同连锁群。该图谱为烟草重要农艺性状的基因定位、以及分子标记辅助选择等研究奠定基础。