Monographs on Theoretical and Applied Genetics – serie

The study of populations is becoming increasingly focused on dynamics. We believe there are two reasons for this trend. The ftrst is the impactof nonlinear dynamics with its exciting ideas and colorful language: bifurcations, domains of attraction, chaos, fractals, strange attractors. Complexity, which is so very much a part of biology, now seems to be also a part of mathematics. A second trend is the accessibility of the new concepts. Thebarriers tocommunicationbetween theoristandexperimentalistseemless impenetrable. The active participationofthe experimentalist means that the theory will obtain substance. Our role is the application of the theory of dynamics to the analysis ofbiological populations. We began our work early in 1979 by writing an ordinary differential equation for the rateofchange in adult numbers which was based on an equilibrium model proposed adecadeearlier. Duringthenextfewmonths weftlledournotebookswithstraightforward deductions from the model and its associated biological implications. Slowly, some of the biological observations were explained and papers followed on a variety of topics: genetic and demographic stability, stationary probability distributions for population size,population growth asabirth-deathprocess, natural selectionanddensity-dependent population growth, genetic disequilibrium, and the stationary stochastic dynamics of adult numbers.

It has become apparent, during discussions with students and colleagues in forest genetics, that a universal concern is the achievement of diverse goals of forestry from fiber production in industrial as well as farm forests to conserving forest ecosystems. Although we generally have several breeding methods available and several species to breed, we seek to satisfy multiple-use goals on diverse sites by management techniques that at best can only partially control edaphic environmental variation. The dominant approach, which was agriculturally motivated, has involved inten­ sive effort with complicated breeding plans on single species for uniform adaptability and single-product plantations. However, this is obviously neither the only, nor necessarily the best, solution for the genetic management of tree species, and thus our intent in this volume is to develop ways to achieve multiple objectives in tree breeding. We include an array of breeding plans from simple iterated designs to sets of multiple populations capable of using gene actions for different traits in different environments for uncertain futures. The presentation is organized around the development of breeding from single-to multiple-option plans, from single to multiple traits, from single to mUltiple environ­ ments, and from single to multiple populations. However, it is not a complete "How To" book, and includes neither exercises nor instructions on data handling. It also does not include discussion of all modes of reproduction and inheritance encountered in plants.

Worldwide, acreage under grassland is estimated to be twice that of cropland. Two closely related genera, Festuca L. (fescues) and Lolium L. (ryegrasses) are of significant value in temperate grasslands. These genera (tribe Poeae, subfamily Pooideae) contain well-adapted, very productive grasses widely distributed in temperate and cool climates in Europe, North and South America, North, East and South Africa, Asia, Australia and New Zealand, where they are used for agricultural and recreational purposes (Jauhar 1993). They are important for grazing, stabilizing soil for agriculture, and enhancing the environment through multiple uses, such as forage, conservation and turf (Barnes 1990). Therefore, in the family Poaceae, the Festuca-Lolium group of grasses is among the most extensively studied by agronomists, plant breeders, animal scientists, taxonomists and cytogeneticists. The potential of biotechno- logical approaches has been recognized for the development of improved fescue and rye grass cultivars (Barnes 1990; Kau11990; Jauhar 1993). 1.1 Agronomic Importance of the Festuca-Lolium Complex The Festuca-Lolium complex involves some well-adapted, highly productive persistent species which are widely used for soil stabilization, for agricultural purposes and as amenity grasses. For temperate grasslands, tall fescue, meadow fescue, Italian ryegrass and perennial ryegrass are particularly impor- tant species which show complementary desirable traits, such as palatability and fast initial growth of the ryegrasses, and winter hardiness, persistency combined with continued high production after the second harvest year of the fescues.

The aim of the monographs is to foster effective intra- and interdisciplinary communication between geneticists, and plant and animal breeders. This is to be achieved by publishing authoritative up-to-date texts; concise, but at the same time comprehensive, monographs, and multiauthor volumes on theoretical and applied genetics. The following broad fields of genetics and breeding are within the scope of the series: Evolutionary genetics Developmental genetics Population genetics Biochemical genetics Ecological genetics Somatic cell genetics Biometrical genetics Agricultural genetics Cytogenetics Mutation breeding Radiation genetics Breeding methodology Acceptable subjects for the Monographs on Theoretical and Applied Genetics are basic and applied aspects of genetic variation; genetic resources; genetic exchange and reproduction; mutagenesis; genotype-environment interaction; gene structure, regulation, action, expression and interaction; chromosomal and extrachromosomal inheritance ofeconomic traits, and genetic models and simulations. September 1975 The Editors Preface Meiotic configurations are looked at from a special point of view in this book: the extraction from them of the maximal amount of quantitative information of genetic interest. Although this requires a certain understanding of their origin and consequences, much of what is known about chromosomes and their for­ mation into the special structures collected under the rather indiscriminate term I "configuration", is not considered relevant for this purpose, and simply neglected.

view than its own proper males should fecundate each blossom." ANDREW KNIGHT Philosophical Transactions, 1799 Pollination mechanisms and reproduction have a decisive bearing upon rational procedures in plant breeding and crop production. This book intends to furnish' under one cover an integrated botanical, genetical and breeding-methodologi­ cal treatment of the reproductive biology of spermatophytes­ mainly angiosperms; it is based on an advanced topical course in plant breeding taught at the Hebrew University of Jerusa­ lem. We have tried to present a coverage which is concise, but as comprehensive as possible, of the pollination mechanism and modes of reproduction of higher plants, and to illustrate topics, whenever practicable, by examples from cultivated plants. Nevertheless, some relevant publications may have escaped our attention or may not be mentioned because of various limitations. The book is organized into three parts. The first part starts with an evaluation of the significance of the different pollination mechanisms for plant breeding and crop produc­ tion, describes modes of reproduction in higher plants and discusses ecology and dynamics of pollination. The second part is devoted to crops propagated by self pollination and describes specific breeding procedures for such crops. The third part details sexual reproduction in higher plants and handles three mechanisms involved in the prevention of self pollination and their utilization in plant breeding: sex expres­ sion, incompatibility, and male sterility.

Since the Russian edition of this book was published in 1975 many new research works have appeared which have made necessary some additions for the English edition, to reflect progress in molecular developmental genetics. Recent important findings in this field have brought about essential corrections to the concept of genetic regulation of the process of cell differentiation. The discovery of the mosaic structure of a gene prompted the re­ evaluation of our considerations about the regulation of gene activity in eukaryotes, and the data about transcriptional events during ontogenesis are of great importance as well. Formerly it was generally accepted that a derepression of genes was responsible for cell differentiation in the process of develop­ ment. Recently three important conclusions have been derived (Davidson and Britten, 1979) which help to pose the problem in a new way: 1) Only a small part of single copy sequences of DNA is represented in nuclear RNA of a given type of cell or tissue: 10% to 20% in sea urchin embryos, 11 % in rat liver, 4% to 6% in Drosophila cell culture, etc. Since only about 10% of single copy sequences represent the structural genes (Davidson and Britten, 1973), transcription of almost the whole set of structural genes occurs.

In late 1971 we were involved in a study of the interaction of radiation with matter and were trying to use measurements of radiation fluorescence in biological molecules to indicate how radiation affected living cells. It soon became apparent that we were working in the dark; the doses we used to get a significant signal were too large to be of interest for radiation biology and although the DNA molecule appeared to be the most likely target molecule we did not know which sort of events and which sort oflesions were the most important. We decided to alter our approach to see if we could find any consistent mathematical order in the radiobiological dose relationships. We found that cell survival curves could be very usefully described by a linear-quadratic dose relationship and very soon came to the somewhat premature but, as it turned out, most effective conclusion that the induction of DNA double strand breaks should be linear-quadratic. In deciding that the DNA double strand break was the crucial and all-important lesion we were able to associate the mathematical analysis with the biology of the cell and were able to relate known properties of the DNA molecule to known radiobiological effects. On the other hand, we were restricted and brought, from an abstract two-hit lesion which could have any property one wished, down to earth, to a defined moleccular structure of nanometer dimensions and well-known functions and properties.

When trying to solicit authors for this book it became apparent that the causal factors for heterosis at the physiological and biochemical level are today almost as obscure as they were 30 years ago. Though biometrical-genetical analyses point to dispersion of complementary genes - not overdominance - as the major cause of the phenomenon, plant breeders' experience still suggests a cautious, pragmatic approach to the dominance-overdominance controversy in breeding hybrid cultivars. Thus we are faced with a striking discordance between our limited comprehension of the causal factors and mechanism of heter­ osis on the one hand, and the extensive agricultural practice of utiliza­ tion of hybrid vigor on the other. Such utilization is the result of the economic value of hybrid combinations displaying superior yields and qualities as well as stability of performance, of benefits derived in breeding programs, and of the enhanced varietal protection of proprietary rights. No comprehensive and critical analysis of the phenomenon of heterosis in economic plants has been published for the last three decades since the now classical book Heterosis, edited by J . W. Gowen (Iowa State College Press, Ames, Iowa, 1952). The present book attempts to fill the gap and to assess the status of our present knowl­ edge of the concept, the basis, the extent, and the application of heterosis in economic plants.

Mutation breeding has been introduced into modern plant breeding in the early 1940's. In spite of pessimistic predictions, the application of experimental mutagenesis has led to encouraging results demonstrating that mutation breeding is a well-functioning method in many crops. So far, more than 500 varieties, developed by means of induced mutations, have been officially released; others have been approved for registration. Many mutants with characters of agronomic interest cannot be utilized directly because of their unsatisfying yielding capacities, or of other negative traits which are partly due to the pleiotropic action of the mutant genes. Sometimes their negative selection value can be overcome by transferring them into the genomes of other varieties. According to experience available, the efficiency of mutant genes can conSiderably vary depending on the genotypic background in which they become effective. The interactions between mutant genes and genotypic back­ ground cannot be predicted. Therefore, mutants with valuable traits should be crossed with many varieties and strains in order to discern positive and negative interactions. In this way, genotypes can be selected in which the mutant gene is able to express its action without showing negative by-effects. This procedure has been used for about 10 years by combining the methods of mutation and crossbreeding. Mutation breeding is predominantly used in annual diploid and allo­ polyploid self-fertilizing crops, while it causes much more difficulties in cross-pollinating species.

Although only about 3 years have passed since the preparation of the original manuscript of this book for the Russian edition, the number of successful experiments on somatic hybridization of higher plants has doubled. Although the main inferences of the first edition still remain in force, most of them have received conclusive experimental support and, moreover, some new con­ clusions have been drawn. It can be expected that these inferences and conclusions will constitute a more or less durable foundation for somatic cell genetics of higher plants. We thus hope this book will also remain useful over the next years, in spite of the rapid progress of experiments and the increase in the number of scientific reports in this field. Though it might appear strange to an uninvolved observer, the principal progress in hybridization of somatic cells of higher plants has been due to plant physiologists (who entered the field by elaborating methods and techniques for plant cell and, later, for isolated protoplast culture) rather than plant geneticists. However, further qualitative improvement in this field is inconceivable without the instillation of genetic ideology and the strict logic of genetic experiments. The main purpose ofthis book is the attempt to organize the available experimental data in terms and cate­ gories of genetic analysis. For this reason, this book lays no claim on being a comprehensive treatise on somatic hybridization.

" . . . . . . Nature has something more in view than that its own proper males should fecundate each blossom. " Andrew Knight Philosophical Transactions, 1799 Sterility implicating the male sex solely presents a paradoxical situation in which universality and uniqueness are harmoniously blended. It maintains a built-in outbreeding system but is not an isolating mechanism, as male steriles, the "self-emasculated" plants, outcross with their male fertile sibs normally. Both genes (nuclear and cytoplasmic) and environment, individually as well as conjointly, induce male sterility, the former being genetic and the latter nongenetic. Genetic male sterility is controlled either exclusively by nuclear genes (ms) or by the complementary action of nuclear (lr) and cytoplasmic (c) genes. The former is termed genic and the latter gene-cytoplasmic male sterility. Whereas genic male sterility exhibits Mendelian inheritance, gene-cytoplasmic male sterility is non-Mendelian, with specific transmissibility of the maternal cytoplasm type. Genetic male sterility is documented in 617 species and species crosses com­ prising 320 species, 162 genera and 43 families. Of these, genic male sterility occurs in 216 species and 17 species crosses and gene-cytoplasmic male sterility in 16 species and 271 species crosses. The Predominance of species exhibiting genic male sterility and of species crosses exhibiting gene-cytoplasmic male sterility is due to the fact that for the male sterility expression in the former, mutation of nuclear genes is required, but in the latter, mutations of both nuclear and cytoplasmic genes are necessary.

The idea for this book was conceived by the late Dr. Irvine A. Watson of the University of Sydney, and he developed the first outline. I was then invited by Dr. Watson to share in its writing. Unfortunately, shortly there­ after, recurring heart problems forced him to curtail his activities and with­ draw from the project. He died before the book could be completed. Dr. Watson's intention was to produce a very practical book that would provide wheat breeders with all of the information necessary to breed success­ fully for resistance to the three wheat rusts: leaf rust, stem rust, and yellow rust. It was intended to be very specific in describing procedures to be used and at the same time provide all of the necessary theoretical background. I hope that I have been successful in meeting these objectives. The book assumes that the reader has some knowledge of plant pathology, genetics, and plant breeding. Extensive use has been made of the literature, but it was not possible to cite allof the papers on a given topic. In making a choice, an attempt was made to choose key papers or more recent papers that provided references to the earlier literature. Acknowledgements This book was written partly at the University of Saskatchewan and partly at the University of California, Davis, while I was on a sabbatical leave.

An introductory discussion of basic chromosome structure andfunction preceeds the main text on the application ofcytogenetic approaches to the analysis of the manipulationof both the genetic make-up and the genetic transmissionsystem of plant breeding material. Analysis using light andelectron microscopy, segregations and molecular techniques,yields information for assessing the material before andafter manipulation. Much attention is given to quantitativemethods. Manipulation not only involves the construction ofspecific genotypes, but also chromosomal transmissionsystems.Although analysis and manipulation in the somatic cycle areconsidered, the focus is on the generative cycle, withemphasis on analysis and subsequent segregation ofspecifically constructed material.The book is intended for plant breeders and other scientistsinterested in the analysis and manipulation of breedingmaterial at the chromosomal level. Comparisons withmolecular and cell biological approaches are made, and thepotential of the various methods is evaluated.

Presented here are modern and classical aspects of cytogenetics as well as biotechnology in relation to improvement of the Festuca-Lolium group of grasses. Festuca and its close relative Lolium are very valuable genera of temperate agriculture. These fascinating genera contain some highly productive, nutritious, and well-adapted grasses widely used for agricultural and recreational purposes world wide. The book is organizedinto 15 chapters devoted to taxonomy and systematics; species evolution and divergence by increase in chromosome number as well as by change in DNA content; genetic control of chromosome pairing and its breeding and phylogenetic implications; B chromosomes, induced polyploidy and haploidy inrelation to varietal improvement; wide hybridization, genome relationships, and plant improvement; genomic balance in relation to hybrid fertility and hererosis breeding; biotechnology and its potential applications in plant improvement. It is of special interest to geneticists, taxonomists, evolutionists, biotechnologists, and plant breeders.

The esculent Lycopersicon esculentum, long thought to be poisonous, has become a major U. S. food crop and source of vitamins and minerals, thanks largely to genetic modification and new production technology Rick (1978) Tomato (Lycopersicon esculentum Mill. ) is one of the most important solana­ ceous vegetable crops grown worldwide under outdoor and indoor conditions. It has become an important commercial crop so far as the area, production, industrial values and its contribution to human nutrition is concerned. During the past few decades tremendous developments have contributed to the knowledge and understanding of various areas of genetics, breeding and biotechnology and voluminous literature has been generated. The purpose of preparing this monograph is to give a comprehensive up-to-date treatment to the various aspects of genetic improvement of tomato. The emphasis has been placed on cytology, classical and molecular genetics, reproductive biology, germplasm resources, hybrid seed production, use of wild taxa, selection/ breeding methods, breeding for abiotic and biotic stresses, processing and quality breeding, improvement for mechanical harvesting, and biotechnology: tissue culture, protoplast fusion, and genetic transformation. These topics are presented in 22 different chapters. However, a few aspects have been discussed in more than one chapter. For example, seed production is treated in chapters 1, 4 and 8; molecular biology/genetic engineering in chapters 3 and 22 and heterosis in chapters 8 and 16.

Because of the great variety of problems which this genus presents to biologists, Oenothera belongs to the best-known genera of plants not used economically. It is further of great value for all those whose research topics are based on genetics, such as developmental and evolutionary biology.

Thisbookisconcernedwiththewaysinwhichcropsmightbedevelopedfor soilsthatare,atthepresent,agriculturallyunproductivebecauseofexcesses and/ordeficienciesofcertainminerals. Wehaveconcentratedonsoils,rather thanonenvironmentalconditionsthatlimitproductivity,sincetherehavebeen anumberofrecenttextsdealingwithtopicssuchasdroughtandtemperature. Theaimisthatthoseworkingtoderivecropsforgrowthonthese"problem" soilsshouldbeawareofthemanydiverseavenuesthatareavailable. These comefromthedisciplinesofplantbreeding,geneticsandphysiology,andthe interfacesthataredevelopingbetweenthem. Thebackground,therequirementstofeedtheprojectedincreaseinhuman population,issetoutintheintroductorychapter. Thenextfivechaptersthen dealwiththeapproachestocropimprovement:themeritsofaconventional breedingprogramme,theimportanceofphysiologicalcharactersinmaking selections,theuseofinvitrotechniques,ofcytogenetics,andthevalueof developingnativeplantsintocropsintheirownright. Althoughsalinityisoften usedasanexample,reflectingtheresearchinterestsofmanyoftheauthors,the methodsandapproachesdescribedhavemuchwiderapplicability.Twochap- tersarethenconcernedmorespecificallywithbreedingfortolerancetoother metaltoxicitiesandwithdeficienciesandtoxicitiesofmicronutrients. Finally,in theconcludingchapter,wesummariseandfindcommongroundbetweenthe differentapproachesandpointsofview. Brighton,April1994 ANTHONYR. YEO TIMOTHY J. FLOWERS Contents Chapter1 Introduction:WorldPopulationandAgriculturalProductivity T. 1. Flowers 1. 1 HowManyPeopleAreThere? . 1 1. 2 AgriculturalRequirements. . 2 1. 2. 1 FoodRequirements...2 1. 2. 2 FoodSupply...4 1. 3 Population-CarryingCapacity...5 1. 4 HowMuchLandIsThere? . 6 1. 5 IncreasingFoodProduction . 7 References...9 Chapter2 ConventionalPlantBreedingforTolerancetoProblemSoils C. N. ChaubeyandD. Senadhira 2. 1 ScreeningTechniques . 11 2. 2 VariabilityinToleranceforSoilStresses . 14 Rice . 15 2. 2. 1 2. 3 GeneticsofToleranceforSoilStresses...16 19 2. 3. 1 GeneLocationandLinkages...CorrelatedChanges...20 2. 3. 2 2. 4 Crop-Improvement . 21 2. 4. 1 Introduction...21 2. 4. 2 PureLineandMassSelection...21 2. 4. 3 HybridisationandSelection. 23 2. 4. 3. 1 PedigreeMethod...23 2. 4. 3. 2 BulkMethod...23 BackcrossBreeding...2. 4. 3. 3 26 2. 4. 3. 4 RecurrentSelection...26 2. 4. 3.5 RapidGenerationAdvanceProcedures...27 2. 4. 4 MutationBreeding...28 2. 4. 5 PolyploidBreeding. 28 2. 4. 6 HeterosisBreeding. 29 2. 5 Summary...29 References...29 VIII Contents Chapter3 PhysiologicalCriteriainScreeningandBreeding A. R. Yeo 3. 1 Introduction...37 3. 2 ReasonsfortheUseofPhysiologicalSelection . 38 3. 2. 1 TheComplexityofTolerance...38 3. 2. 2 ImportingTolerancefromWildRelatives . 39 3. 2. 3 MeasuringStressTolerance . 40 3. 2. 4 InteractionBetweenEnvironmentalStresses...42 3. 2. 5 LimitationstotheUseofYieldasaSelectionCriterion...42 3. 3 Salinity . 43 3. 3. 1 BasicProblems...43 SaltExclusion...44 3. 3. 2 3. 3. 3 ConditionsRequiringOsmoticAdjustment. . 45 3. 3. 4 CharacteristicsNeededinSalt-TolerantPlants . 46 3. 3. 4. 1 ControlofSaltUptake...

Wild taxa are invaluable sources of resistance to diseases, insects/ pests, nematodes, temperature extremes, salinity and alkalinity stresses, and also of nutritional quality; adaptation; genetic diversity and new species. Utilization of wild relatives of a crop depends largely upon its crossability relations with cultivated varieties. Sev­ eral wild species are not crossable with the commercial cultivars due to various isolation barriers. Furthermore, in a few cases, hybridiza­ tion is possible only in one direction and reciprocal crosses are not successful, thus depriving the utilization of desired cytoplasm of many species. However, techniques have been developed to over­ come many barriers and hybrid plants are produced. New crop species have been developed by overcoming the F 1 sterility and producing amphidiploids and such crops are commercially being grown in the field. The segregation pattern ofF 1 hybrids produced by distant hybridization in segregating generations are different from the intervarietal hybrids. In former cases, generally, unidirectional segregation takes place in early generations and accordingly, selec­ tion procedures are adopted. In most of the cases, backcross or modified backcross methods have been followed to utilize wild species, and thus numerous types of resistance and other economical attributes have been transferred in the recurrent parents. Protoplast fusion has been amply demonstrated in a number of cases where sexual hybridization was not possible and, as a result, hybrids have been produced.

A century of research on heterostylous plants has passedsince the publication of Charles Darwin's book "TheDifferent Forms of Flowers on Plants of the Same Species" in1877 summarizing his extensive observations and experimentson these complex breeding systems involving geneticpolymorphisms of floral sex organs. Since then heterostylousplants have provided a rich source of material forevolutionary biologists and today they represent one of theclassic research paradigms for approaches to the study ofevolution and adaptation. The present book is the firstmodern and comprehensive accont of the subject. In 10chapters it is concerned with the evolution, genetics,development, morphology, and adaptive significance ofheterostyly. Broad syntheses of research on heterostyly aswell as new theoretical ideas and experimental data areincluded.