Mineral Nutrition of Higher Plants, 2nd edition, H. Marschner. Academic Press, London (1995), 889, (ISBN 0-12-473543-6). Price: 29.95 Pound Sterling

Detection and analysis of genetic variation can help us to understand the molecular basis of various biological phenomena in plants. Since the entire plant kingdom cannot be covered under sequencing projects, molecular markers and their correlation to phenotypes provide us with requisite landmarks for elucidation of genetic variation. Genetic or DNA based marker techniques such as RFLP (restriction fragment length polymorphism), RAPD (random amplified polymorphic DNA), SSR (simple sequence repeats) and AFLP (amplified fragment length polymorphism) are routinely being used in ecological, evolutionary, taxonomical, phylogenic and genetic studies of plant sciences. These techniques are well established and their advantages as well as limitations have been realized. In recent years, a new class of advanced techniques has emerged, primarily derived from combination of earlier basic techniques. Advanced marker techniques tend to amalgamate advantageous features of several basic techniques. The newer methods also incorporate modifications in the methodology of basic techniques to increase the sensitivity and resolution to detect genetic discontinuity and distinctiveness. The advanced marker techniques also utilize newer class of DNA elements such as retrotransposons, mitochondrial and chloroplast based microsatellites, thereby revealing genetic variation through increased genome coverage. Techniques such as RAPD and AFLP are also being applied to cDNA-based templates to study patterns of gene expression and uncover the genetic basis of biological responses. The review details account of techniques used in identification of markers and their applicability in plant sciences.

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Advances in molecular marker techniques and their applications in plant sciences

Principles of Plant Breeding

D'un point de vue historique, le developpement de la technique d'elevage des bourdons (Bombus spp.) se caracterise par trois phases. Durant la 1 re phase, les reines ont ete attirees dans des domiciles artificiels et diverses techniques ont ete utilisees pour stimuler les reines a fonder une colonie. Les connaissances acquises durant cette phase ont rendu possibles les etudes de terrain concernant la biologie des bourdons. Elles ont aussi ete utilisees pour ameliorer la pollinisation des cultures dont la floraison etait synchrone du developpement naturel des colonies. La comprehension grandissante des mecanismes qui regulent l'activation des reines et leur production d'oeufs et des mecanismes qui gouvernent la colonie dans son ensemble a permis aux chercheurs d'elever des bourdons toute l'annee. La 3 e phase a vu la transition vers l'elevage commercial, technique qui necessite une connaissance plus detaillee des moyens pour maximiser la reussite de l'elevage. En moins de 20 ans, l'elevage commercial a atteint une production annuelle d'un million de colonies. Bien que de nombreuses especes, parmi les 250 existantes, aient ete elevees, seules cinq especes sont utilisees dans les programmes de pollinisation (Tab. III). Parmi ces cinq especes, l'espece eurasienne Bombus terrestris est de loin la plus importante sur le plan commercial, suivie par l'espece nord-americaine Bombus impatiens. Le tableau I fournit des details sur les pays qui utilisent ces especes et sur les societes qui les produisent et les vendent. L'acceptation rapide des bourdons et leur vaste introduction en tant que pollinisateurs peut s'expliquer par les avantages economiques par rapport aux techniques plus anciennes, souvent artificielles. La figure 1 montre la transition rapide qui s'est operee dans le cas des tomates sous serre aux Pays-Bas. Et la figure 2 l'accroissement des ventes mondiales. Le tableau II presente l'evolution dans le temps de l'expansion mondiale. Aujourd'hui les bourdons sont utilises pour la production agricole sur tous les continents. Bien qu'ils pollinisent des cultures de plein champ et des cultures sous cage (Tab. IV), leur utilisation predomine dans la production de tomates sous serre. Celle-ci couvre 40 000 ha et represente une valeur de 12 000 millions d'euros. La pollinisation par les bourdons entraine une baisse des couts de production, un accroissement des rendements et une meilleure qualite des fruits, ainsi qu'une plus grande utilisation de la lutte biologique contre les ravageurs des cultures. A cause de l'acceptation generale de la nouvelle technologie, les gains financiers pour les agriculteurs ont rapidement disparus tandis que le consommateur a continue de beneficier d'une meilleure qualite. La plupart des colonies ne sont produites que par un petit nombre de societes et sont transportees sur de longues distances. En fait elles sont expediees dans des regions eloignees de leur habitat d'origine. Il est donc justifie d'avoir des craintes sur les consequences ecologiques. Par exemple, B. terrestris a recemment ete implante au Japon, au Chili et en Tasmanie. La, il entre en competition avec les especes indigenes et peut transmettre des parasites et des pathogenes de bourdons a de nouveaux hotes. Il faut donc preferer la production locale de pollinisateurs autochtones.

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A century of advances in bumblebee domestication and the economic and environmental aspects of its commercialization for pollination

The origin of plant cell and tissue culture can be found in a treatise published during the mid-18th century, entitled La Physique des Arbes, that describes the formation of callus tissue following the for mation of a ring of cortex from elm trees. Over the next two centuries, the discovery of plant growth hormones, in particular auxins and cytokinins, and detailed analyses on the nutritional requirements of plants, led to the formulation of media that could maintain actively dividing cultures derived from gymnosperms, and both dicotyledon ous and monocotyledonous angiosperms. However, much of the prog ress and technological development in the in vitro propagation of plant cells, tissues, and organs has occurred during the last 25 years. Recently, plant tissue culture techniques have been used as basic tools in the rapidly expanding field of plant biotechnology for the development and clonal propagation of new and/or improved plant varieties. Plant tissue culture is used for the micropropagation of commercially valuable cultivars that include ornamentals, oil palm, Glycyrrhiza, Pyrethrum, pine, Eucalyptus, sugar cane, and potatoes. Cultured plant tissue is also used for the selection of cells and, ul timately, the regeneration of plants that are tolerant to physical stresses such as pathogens, drought, and temperature extremes, and to chemical stress agents such as salinity, herbicides, proteins, and pyrethrins. In addition, new plants have been produced by the fusion of protoplasts prepared from cultured cells of different species in cluding sunflower and french bean, tomato and potato, and various cultivars of Datura. Finally, bacterial vectors and various mechanical methods have been used to introduce foreign genes into cultured plant tissues. Genetic transformation can result in profound changes in the phenotype and/or biochemical profile of the regenerated trans genic plants that are not characteristic of the wild type. An impressive variety of technologies in tissue culture, genetic manipulation, and molecular biology have been developed for nu merous plant species. Many of these techniques, sometimes referred to as plant biotechnology, have been extensively summarized and compiled in a well-balanced collection of easy-to-follow protocols presented in three separate, but complimentary, volumes. Plant Cell, Tissue and Organ Culture consists of 22 chapters (with 86 figures) and 5 appendices. The chapters cover critical aspects of (a) the es sential requirements for the operation of a plant tissue culture lab oratory; (b) the basic procedures of micropropagation, regeneration, and somatic embryogenesis; (c) some specific applications of organ culture systems such as embryo rescue and culture, and anther and microspore culture for haploid and double haploid production; (d) elementary transformation technology; and (e) useful microtechnique and analytical protocols specifically adapted to cultured tissues and cells. The appendices provide a convenient summary of media for mulations and commercial suppliers for the materials described in the text.

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Plant Cell, Tissue and Organ Culture

Determination of screening techniques to salinity tolerance in tomatoes and investigation of genotype responses

https://research.sabanciuniv.edu/130/1/stvkaf01883.pdf

Genotypic variation in the response of pepper to salinity

Germplasm characterization is essential and molecular markers provide valuable information for breeding programs. Sequence-related amplified polymorphism (SRAP) and phenotypic markers were studied to determine diversity and relationships among 23 okra (Abelmoschus esculentus (L) Moench) genotypes. The 39 combinations of forward and reverse SRAP primers were used to evaluate the 21 Turkish and two randomly selected USA genotypes as outgroups, and produced 97 scorable markers, of which 50% was polymorphic for all 23 genotypes. Seventeen out of the 23 genotypes (74%) were distinguished from each other with mean similarity of 0.93. As to phenotypic markers, 33 heritable traits were evaluated in field with ten replications, 28 of them (85%) were found to be polymorphic. The UPGMA (unweighted-pair group method arithmetic average) dendrogram based on the 33 phenotypic markers distinguished all genotypes, but failed to detect any geographic association of okra genotypes, being consistent with previous study. It can be concluded that SRAP markers are useful for studying diversity and relationships among okra germplasm, and have potential in marker-aided selection, linkage mapping, and evolutionary studies.

Diversity and relationships among Turkish okra germplasm by SRAP and phenotypic marker polymorphism

Fusarium wilt (Fusarium oxysporum Schlecht. f. sp. melongenae) is a vascular disease of eggplant (Solanum melongena L.). The objectives of this work were (1) to confirm the monogenic inheritance of fusarium wilt resistance in eggplant, (2) to identify molecular markers linked to this resistance, and (3) to develop SCAR markers from most informative markers. We report the tagging of the gene for resistance to fusarium wilt (FOM) in eggplant using SRAP, RGA, SRAP-RGA and RAPD markers. Analysis of segregation data confirmed the monogenic inheritance of resistance. DNA from F2 and BC1 populations of eggplant segregating for fusarium wilt resistance was screened with 2,316 primer combinations to detect polymorphism. Three markers were linked within 2.6 cM of the gene. The codominant SRAP marker Me8/Em5 and dominant SRAP-RGA marker Em12/GLPL2 were tightly linked to each other and mapped 1.2 cM from the resistance gene, whereas RAPD marker H12 mapped 2.6 cM from the gene and on the same side as the other two markers. The SRAP marker was converted into two dominant SCAR markers that were confirmed to be linked to the resistance gene in the F2, BC1 and F2 of BC3 generations of the same cross. These markers provide a starting point for mapping the eggplant FOM resistance gene in eggplant and for exploring the synteny between solanaceous crops for fusarium wilt resistance genes. The SCAR markers will be useful for identifying fusarium wilt-resistant genotypes in marker-assisted selection breeding programs using segregating progenies of the resistant eggplant progenitor used in this study.

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Development of SRAP, SRAP-RGA, RAPD and SCAR markers linked with a Fusarium wilt resistance gene in eggplant

The genetic relationships among 56 melon (Cucumis melo L.) genotypes collected from various parts of Turkey were determined by comparing their phenotypic and molecular traits with those of 23 local and foreign melon genotypes to investigate the taxonomic relationships and genetic variation of Turkish melon germplasm. Sixty-one phenotypic characters and 109 polymorphic RAPD markers obtained from 33 primers were used to define the genetic similarity among the melon genotypes by dendrograms or two and three dimensional scaling. There were high correlations (r ≥ 0.97) among the four resulting matrices used in molecular characterization. The correlations between phenotypic (Euclidean) and molecular Euclidean, Jaccard, Simple matching, and Nei analyses were r = 0.41, r = −0.40, r = −0.43 and r = −0.40, respectively. Related genotypes or genotypes collected from similar regions were partitioned to similar clusters. Both analyses (phenotypic and molecular) indicated that non-sweet melon types were dissimilar from sweet types and diversity of Turkish melon genotypes was higher than that of sweet foreign cultivars examined, but similar to that of the reference accessions employed. It was also observed that sweet Turkish melon genotypes belonging to groups inodorus and group cantalupensis were highly variable and could have intermated or have crossed with other non-sweet types.

Kazim Abak

Papers

Determination of screening techniques to salinity tolerance in tomatoes and investigation of genotype responses

Genotypic variation in the response of pepper to salinity

Diversity and relationships among Turkish okra germplasm by SRAP and phenotypic marker polymorphism

Development of SRAP, SRAP-RGA, RAPD and SCAR markers linked with a Fusarium wilt resistance gene in eggplant

Evaluation of genetic diversity in Turkish melons ( Cucumis melo L.) based on phenotypic characters and RAPD markers