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UNIVERSITY of FLORENCE Department of Plant, Soil and Environmental Science. EVALUATION OF THE GENETIC VARIABILITY USING MOLECULAR MARKERS IN POPULATIONS OF CULTIVATED SPECIES AND ITS UTILIZATION IN THE GENETIC IMPROVEMENT OF THE ZOLFINO BEAN. Lisetta Ghiselli and Stefano Benedettelli
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UNIVERSITY of FLORENCE Department of Plant, Soil and Environmental Science EVALUATION OF THE GENETIC VARIABILITY USING MOLECULAR MARKERS IN POPULATIONS OF CULTIVATED SPECIES AND ITS UTILIZATION IN THE GENETIC IMPROVEMENT OF THE ZOLFINO BEAN Lisetta Ghiselli and Stefano Benedettelli lisetta.ghiselli@unifi.it Biodiversity in Agroecosystems Milano, 24-25 February 2011
WHAT ARE THE PROBLEMS FOR THE CULTIVATION OF “ZOLFINO” ? The Zolfino cv. is a typical Tuscan common bean It is cultivated in the hilly and mountainous region of Pratomagno Pratomagno landscape Traditional food PROBLEMS GENETIC EROSION LOW PRODUCTION The actual breeding systems in practice could produce varieties not suitable for this cultivation
“GREEN REVOLUTION” Caused a loss of GENETIC DIVERSITY Contributed to world famine reduction • The breeding systems were changed. • This resulted in the selection of cv with: • High production, • Uniform crops, • Introduction of standards, • Homogeneous plants LOSS of numerous heterogeneous traditional farmers’ varieties
NOW • 150 species of food crops are cultivated • Mankind lives off no more than 12 plant species
DANGERS OF GENETIC EROSION Modern Breeding systems in practice Green revolution (intensive agricultural systems, environmental pollution, ground erosion) High degree of genetic similarity of new varieties GENETIC EROSION Loss of local species and varieties usually results in an irreversible loss of genetic diversity. This has dangerously reduced the genetic pool that is available for natural selection • Problems of adaptability of species to environmental change (climate change), • Increase in the vulnerability of agricultural crops to abiotic and biotic stress (pests and diseases)
DANGERS OF GENETIC EROSION History has provided some important examples of these dangers
EXPERIMENT ON THE ZOLFINO BEAN To address the problem of genetic uniformity, an experiment was carried out on the Zolfino bean. The experiment was conducted over five years. The OBJECTIVE was to select genotypes with different properties that could be used for a multi-line variety constitution.
EXAMPLE: “ZOLFINO” BREEDING COLLECTION GERMPLASM Field trials evaluation DNA extraction Seed production Genetic evaluation of the gene pool Pure lines Pure lines combination Varietal trial evaluations MULTI-LINE VARIETY CONSTITUTION
VARIABLES CONSIDERED • GENOTYPE FIELD EVALUATION • Morphological • Production • Tolerance to biotic and abiotic stress • Quality characteristics • In collaboration with the farmers • LABORATORY ANALYSIS • Genetic characterization with SSR primers • Genetic variability with Storage Proteins • Diseases monitoring and characterization
LINE EVALUATION AND SEED PRODUCTION 1,8 m 2 m For the production of seed, the material was isolated from insects in tunnels. This was done to promote self-impollination
MORPHOLOGICAL CHARACTERISTICS Plant data in the field • date of flowering • estimation of fruit development • plant height • n. of side-branches • viral incidence Plot Data • % Emergence • % Flowering • Production t/ha Post-harvestparameters • n. of pods • pod length • pod width • n. of seeds per pod • weight of 1000 seeds
94 kD ► 67 kD ► •1 •2 •3 43 kD ► •4 •5 •6 7• 8• •9 •10 •11 30 kD ► 12• 20.1 kD ► F1 F5 F1 F1 F6 F7 F1 F2 F3 F4 F1 Evaluation of Genetic Variability To evaluate the genetic variation in the selected lines two methods were used 4 different STORAGE PROTEINS 12 different SSR Primer Combinations
STATISTICAL DATA ANALYSIS • Quantitative characters • Univariate analysis of variance (ANOVA): • years and locality were considered random effect factors • genotypes were considered fixed effect factors • Multivariate analysis of variance (MANOVA) included • the Principle Component Analysis PCA and cluster identification (k-means clustering) • Molecular data • Jaccard index • Sahn clustering method • The results were shown using Dendrograms
RESULTS: MORPHOLOGICAL AND YIELD CHARACTERISTICS • The PCA showed the distribution of the lines on the basis of the morphological and yield data. • We obtained an initial phenotypic classification, where it was possible to observe homogeneity in each group. • These genotypes, respected the varietal standards of the modern varieties.
RESULTS: GENETIC CHARACTERISTICS This dendrogram shows the distribution of the lines representative of the populations of Zolfino on the basis of the genetic variability obtained from using the SSR primers
By combining the genetic and morphological characteristics, it was possible to obtain pure lines for the multi-line variety constitution. G 19 G 36 G 27 G 15 G 13 G 31 G 17 G 1 G 22 G 25 G 28 G 23 G 16 G 24 G 40 G 46 G 14 G 38 The aim was to have the maximum variability in each homogeneous class
MULTI-LINE VARIETY CONSTITUTION On the basis of the results, after the fourth year, we constituted five multi-line varieties. Each variety was produced from the combination of four different genotypes extracted from 18 genotypes.
EXPERIMENTAL FIELD EVALUATION It is very important to evaluate the behaviour of the plants under field conditions for many years The photo shows the experimental field trials to evaluate the morphological and productive characteristics in the final year. The samples were cultivated in a randomized block design with three replicates in four localities in Tuscany
GENERAL COMBINING ABILITY AND SPECIFIC COMBINING ABILITY (SCA) It is also important to evaluate the combining ability of each single genotype with all the other genotypes For example combining 5 genotypes, 2 at a time, it is possible to have 10 different combinations These formula (Partial Diallelic Cross) are used to evaluate the Combining Ability (general and specific) of each single genotype (by Griffing 1956) The method allows the identification of those genotypes that combine better with others
CONCLUSIONS The combination of Multivariate analysis with Genetic variability data are useful: • To define new varieties that are suitable as food crops and that are adapted to different environments • To obtain multi-line varieties which contain elevated genetic variability, and consequently an elevated stability in production • To monitor the genetic changes of frequencies of genotype within both populations and varieties, useful for germplasm conservation and for variety stability
Tank you very much for your attention