69174 - Introduction To Agricultural Genetics And Plant Genetic Improvement

Learning outcomes

At the end of the course, the student knows the basics of Mendelian, quantitative and population genetics, as well as the main biotechnological applications. The student also knows the most important methods of selection for quality and quantity of production and is able to grasp the genetic aspects of greater economic and management importance aimed at promoting correct agricultural practice and the sustainable use of the products.

Course contents

Prerequisites


The student who accesses this teaching must possess a good knowledge of the foundations of mathematics, chemistry and plant biology, as well as a knowledge of the foundations of statistical analysis (sample mean, variance and standard deviation). These prerequisites are provided by the basic teachings delivered during the first year of the course.

Contents of the theoretical teaching unit (36 hours)

1) Development cycles of animal and vegetable organisms. Structure of the reproductive system of plants. Mitosis and meiosis. The genetic material in the plant cell. (1 hour).

The aspects of plant and cellular biology that are fundamental and necessary for a full understanding of the genetics of plants of agricultural interest are illustrated.

2) Mendel's laws: dominance and recessivity, alleles and genes, segregation, assortment of characters and genes. chi test2. Extensions of Mendel's laws: multiple alleles, incomplete dominance and codominance, gene interaction (epistasis), pleiotropy. (2 hours).

The fundamentals of the laws governing the transmission of hereditary characters in all organisms and the main statistical test used for the experimental verification of these laws in experimental materials are illustrated.

3) The chromosome theory of inheritance. Sex chromosomes. The karyotype. Sexual systems in plants, monoecy and dioecy. Sex determination in plants of agricultural interest. Cross incompatibility systems in plants (4 hours).

The relationship genetic material - chromosomes is illustrated, with particular reference to examples related to the genetic control of sex determination in plant species of agricultural interest.

4) Gene concatenation and recombination frequency, centiMorgan, crossing-over, genetic map. (4 hours).

The theoretical and molecular basis of the crossing-over mechanism and its consequences for the production of genetic maps are illustrated.

5) Biochemistry of nucleic acids: Watson and Crick model, DNA replication, RNA transcription and maturation, translation and protein synthesis. Genetic code. Gene structure. Regulation of gene expression and the lactose operon. Central dogma of molecular biology. (2 hours).

The chemical structure and the main biochemical-functional aspects of the nucleic acids at the basis of the expression of the phenotypic characters are illustrated. This lesson also aims to provide the basis for understanding the progress of biotechnology in the field of plant breeding.

6) Genetics of quantitative traits: Johannsen experiment, pure lines, variation due to environmental and genetic causes, heritability. Nilsson-Ehle and East experiments. Multifactorial hypothesis and heritability. (2 hours).


The theoretical foundations are provided for understanding the laws of heredity applied to quantitative (or metric) traits, the main traits of interest for the genetic improvement of agricultural crops.

7) Mutations: gene, chromosomal, genomic (polyploidy and aneuploidy). Transposable elements. Mutagenesis. Origin and genetics of cultivated wheats. (1 hour).

The genetic factors and mechanisms through which the hereditary material is modified are illustrated, laying the foundations for evolution and genetic improvement.

8) Overview of population genetics and Hardy-Weinberg's law. Evolutionary forces and speciation. Inbreeding and heterosis. (4 hours).

The genetic-statistical bases that regulate the modification of allele frequencies in populations over time are illustrated, with reference to the selective process in genetic improvement, and to adaptation and speciation in natural populations. The concept of heterosis and inbreeding is introduced, with examples of the exploitation of heterosis in the genetic improvement of agricultural species.

9) Fundamentals of genetic engineering: technologies (agrobacterium and biolistic methods), types of main events. Diffusion in the world of GM agricultural crops. (4 hours).
The main technical and methodological aspects associated with the production of plants and genetically modified organisms (GMOs) are introduced, and the main examples are illustrated.

10) Genomics and genetic markers: classes, characteristics and main applications. Introduction to molecular marker assisted selection (MAS). (4 hours).
The concept of genomics and the use of genomic tools (in particular, molecular markers) in the study of plant genetics is introduced.


11) Elements of genetic improvement of agricultural crops. Genetic structure of cultivated species. Origin of cultivated plants and domestication (4 hours).


Notes on the discipline of plant genetic improvement are offered and the genetic and historical origins of the main agricultural crops are illustrated.

12) Case studies: relevant contributions of genetics to the improvement of the main agricultural crops in Italy and in the world (4 hours)

Specific cases of fundamental contributions of genetics to the improvement of agricultural crops in terms of productivity, resistance to diseases, abiotic stresses, improvement for qualitative aspects, etc. are analysed.

Contents of the two teaching units of exercises (16 hours + 8 hours)

Exercise teaching unit n. 1 (16 hours) - Collection of phenotypic data and problem solving of Mendelian genetics and quantitative genetics


Some problems of Mendelian genetics, quantitative genetics and/or population genetics are presented, addressed and solved in the classroom, with evaluation of the various hypotheses through the application of statistical tests (e.g. chi2), and final formulation of a hypothesis on genetic control underlying the process illustrated by the problem. As regards the part of the activity on the genetics of quantitative traits, the students are accompanied by the teacher to the catalogue/experimental field located at the Department (in viale Fanin), where they carry out an experience of collecting observations and measurements for traits of plants (e.g. height, plant habit, etc.), in parcels previously prepared by the teacher, in order to evaluate the genetic and environmental components of the phenotypic variation between plants.


At the end of the u.d. of exercise no. 1 the student will have direct experience of the application of statistical tests (Chi2, t-student) commonly used to solve problems of Mendelian genetics in the genetic control of simple traits in animals and plants, will know how to approach the analysis of the variability of quantitative traits in plants, has gained experience in the evaluation of the effects of genes and the environment on the determination of characteristics of agronomic interest in plants.


Exercise teaching unit n. 2 (8 hours) - Insights into molecular genetics and plant genomics


In this u.d. an in-depth study, from a technical-practical point of view, of applicative aspects of genetic engineering and genomics in plants of agricultural interest, previously covered in the frontal lessons, will be carried out. The in-depth analysis will also be carried out through visits to the plant genomics research laboratories of the DipSA, and through seminar activities carried out by researchers from public and private bodies, experts in the sector, and invited by the teacher. The techniques and systems illustrated include PCR (Polymerase Chain Reaction) in diagnostics and marker-assisted selection (MAS), and genetic transformation by biolistic method.


At the end of the u.d. of exercise no. 2 the student will have acquired familiarity with some of the main techniques currently used in the field of DNA-based diagnostics (PCR), the production of GMOs, and the applications of genetic improvement in the seed and nursery sector of the same.

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Readings/Bibliography

Russell PJ et al GENETICA AGRARIA. EdiSES, 2016.

Students who wish to make the oral exam in English should contact the professor for obtaining dedicated textbook and informative materials.

Teaching methods

The course is divided into three teaching units. In the first, frontal lessons, the main aspects of the discipline are exposed (genetics of plants of agricultural interest) as described in the above program (36 frontal hours). The two further teaching activities (of 16 and 8 hours, respectively) include practical exercises in which genetic investigation methods are studied in depth (observation and detection of characters, counting, calculations of frequencies and other statistical parameters, production of hypotheses and evaluation with statistical tests) aimed at illustrating the experimental work methods, also to contribute to the development in the student of a capacity for critical analysis of the results, based on scientific criteria. The exercises also include educational visits to molecular biology laboratories and experimental fields. The teacher invites researchers working in the public and private genetic improvement sectors to class for seminars and interaction and discussion with the students.

Assessment methods

The teaching is part of the Integrated Course 27300 BIOLOGIA VEGETALE E GENETICA AGRARIA (C.I.) together with the following teaching: 69173 ELEMENTI DI BIOLOGIA VEGETALE. Therefore, the assessment of the integrated course jointly takes into account the level of knowledge and skills acquired by the student in relation to the contents of the two aforementioned courses. The learning of the Elements of Agricultural Genetics is verified through a written exam. The written exam consists of a test of 30 closed-ended questions (that is, each question is associated with 3 answers of which only one is the right one), or open-ended. The questions relate to all aspects of genetics developed both in the theoretical teaching unit and in the two practical teaching units. The duration of the written test is 60 minutes.


Students who wish to take the exam in English are allowed.

Teaching tools

The use of a PC and video projector is foreseen for the theoretical teaching unit. For the teaching units of exercises, direct investigation (observations, counts, measurements with simple instruments) by the student on plant materials in the field and in the greenhouse, appropriately prepared by the teacher, is envisaged.

Office hours

See the website of Silvio Salvi