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Genetic Analysis Of Quantitative Trait Loci With Recombinant Inbreds In Maize
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Book Synopsis Genetic Analysis of Quantitative Trait Loci with Recombinant Inbreds in Maize by : David Frederick Austin
Download or read book Genetic Analysis of Quantitative Trait Loci with Recombinant Inbreds in Maize written by David Frederick Austin and published by . This book was released on 1995 with total page 426 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Genetic Analysis of Quantitative Trait Loci with Inbred and Hybrid Progeny of Maize by : David Frederick Austin
Download or read book Genetic Analysis of Quantitative Trait Loci with Inbred and Hybrid Progeny of Maize written by David Frederick Austin and published by . This book was released on 1997 with total page 426 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first objective of this study was to compare quantitative trait loci (QTL) detection in two climatically diverse environments in a population of F6:-- lines of an elite maize (Zea mays L.) single-cross. The second objective was to detect QTL for general (GCA) and specific (SCA) combining ability effects in hybrid progeny of F2:3 and F6: lines from the same population. Evaluations of both inbred per se and hybrid progeny from the same population enabled comparisons between QTL controlling the two progeny types. The results from the F6:-- inbred progeny evaluations suggest that QTL detection can be greatly affected by environmental conditions with only 17% (grain yield traits) and 35% (morphological traits) of the QTL detected among the stress and nonstress environments being detected in both environments. The mean environment was effective in detecting 68% (morphological traits) and 54% (grain yield traits) of the QTL detected in either of the individual environments.
Book Synopsis Genetic Analysis of Leaf Angle and Tassel Traits in Maize by : Suzanne M. Mueller
Download or read book Genetic Analysis of Leaf Angle and Tassel Traits in Maize written by Suzanne M. Mueller and published by . This book was released on 2000 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Quantitative Genetics in Maize Breeding by : Arnel R. Hallauer
Download or read book Quantitative Genetics in Maize Breeding written by Arnel R. Hallauer and published by Springer Science & Business Media. This book was released on 2010-09-28 with total page 669 pages. Available in PDF, EPUB and Kindle. Book excerpt: Maize is used in an endless list of products that are directly or indirectly related to human nutrition and food security. Maize is grown in producer farms, farmers depend on genetically improved cultivars, and maize breeders develop improved maize cultivars for farmers. Nikolai I. Vavilov defined plant breeding as plant evolution directed by man. Among crops, maize is one of the most successful examples for breeder-directed evolution. Maize is a cross-pollinated species with unique and separate male and female organs allowing techniques from both self and cross-pollinated crops to be utilized. As a consequence, a diverse set of breeding methods can be utilized for the development of various maize cultivar types for all economic conditions (e.g., improved populations, inbred lines, and their hybrids for different types of markets). Maize breeding is the science of maize cultivar development. Public investment in maize breeding from 1865 to 1996 was $3 billion (Crosbie et al., 2004) and the return on investment was $260 billion as a consequence of applied maize breeding, even without full understanding of the genetic basis of heterosis. The principles of quantitative genetics have been successfully applied by maize breeders worldwide to adapt and improve germplasm sources of cultivars for very simple traits (e.g. maize flowering) and very complex ones (e.g., grain yield). For instance, genomic efforts have isolated early-maturing genes and QTL for potential MAS but very simple and low cost phenotypic efforts have caused significant and fast genetic progress across genotypes moving elite tropical and late temperate maize northward with minimal investment. Quantitative genetics has allowed the integration of pre-breeding with cultivar development by characterizing populations genetically, adapting them to places never thought of (e.g., tropical to short-seasons), improving them by all sorts of intra- and inter-population recurrent selection methods, extracting lines with more probability of success, and exploiting inbreeding and heterosis. Quantitative genetics in maize breeding has improved the odds of developing outstanding maize cultivars from genetically broad based improved populations such as B73. The inbred-hybrid concept in maize was a public sector invention 100 years ago and it is still considered one of the greatest achievements in plant breeding. Maize hybrids grown by farmers today are still produced following this methodology and there is still no limit to genetic improvement when most genes are targeted in the breeding process. Heterotic effects are unique for each hybrid and exotic genetic materials (e.g., tropical, early maturing) carry useful alleles for complex traits not present in the B73 genome just sequenced while increasing the genetic diversity of U.S. hybrids. Breeding programs based on classical quantitative genetics and selection methods will be the basis for proving theoretical approaches on breeding plans based on molecular markers. Mating designs still offer large sample sizes when compared to QTL approaches and there is still a need to successful integration of these methods. There is a need to increase the genetic diversity of maize hybrids available in the market (e.g., there is a need to increase the number of early maturing testers in the northern U.S.). Public programs can still develop new and genetically diverse products not available in industry. However, public U.S. maize breeding programs have either been discontinued or are eroding because of decreasing state and federal funding toward basic science. Future significant genetic gains in maize are dependent on the incorporation of useful and unique genetic diversity not available in industry (e.g., NDSU EarlyGEM lines). The integration of pre-breeding methods with cultivar development should enhance future breeding efforts to maintain active public breeding programs not only adapting and improving genetically broad-based germplasm but also developing unique products and training the next generation of maize breeders producing research dissertations directly linked to breeding programs. This is especially important in areas where commercial hybrids are not locally bred. More than ever public and private institutions are encouraged to cooperate in order to share breeding rights, research goals, winter nurseries, managed stress environments, and latest technology for the benefit of producing the best possible hybrids for farmers with the least cost. We have the opportunity to link both classical and modern technology for the benefit of breeding in close cooperation with industry without the need for investing in academic labs and time (e.g., industry labs take a week vs months/years in academic labs for the same work). This volume, as part of the Handbook of Plant Breeding series, aims to increase awareness of the relative value and impact of maize breeding for food, feed, and fuel security. Without breeding programs continuously developing improved germplasm, no technology can develop improved cultivars. Quantitative Genetics in Maize Breeding presents principles and data that can be applied to maximize genetic improvement of germplasm and develop superior genotypes in different crops. The topics included should be of interest of graduate students and breeders conducting research not only on breeding and selection methods but also developing pure lines and hybrid cultivars in crop species. This volume is a unique and permanent contribution to breeders, geneticists, students, policy makers, and land-grant institutions still promoting quality research in applied plant breeding as opposed to promoting grant monies and indirect costs at any short-term cost. The book is dedicated to those who envision the development of the next generation of cultivars with less need of water and inputs, with better nutrition; and with higher percentages of exotic germplasm as well as those that pursue independent research goals before searching for funding. Scientists are encouraged to use all possible breeding methodologies available (e.g., transgenics, classical breeding, MAS, and all possible combinations could be used with specific sound long and short-term goals on mind) once germplasm is chosen making wise decisions with proven and scientifically sound technologies for assisting current breeding efforts depending on the particular trait under selection. Arnel R. Hallauer is C. F. Curtiss Distinguished Professor in Agriculture (Emeritus) at Iowa State University (ISU). Dr. Hallauer has led maize-breeding research for mid-season maturity at ISU since 1958. His work has had a worldwide impact on plant-breeding programs, industry, and students and was named a member of the National Academy of Sciences. Hallauer is a native of Kansas, USA. José B. Miranda Filho is full-professor in the Department of Genetics, Escola Superior de Agricultura Luiz de Queiroz - University of São Paulo located at Piracicaba, Brazil. His research interests have emphasized development of quantitative genetic theory and its application to maize breeding. Miranda Filho is native of Pirassununga, São Paulo, Brazil. M.J. Carena is professor of plant sciences at North Dakota State University (NDSU). Dr. Carena has led maize-breeding research for short-season maturity at NDSU since 1999. This program is currently one the of the few public U.S. programs left integrating pre-breeding with cultivar development and training in applied maize breeding. He teaches Quantitative Genetics and Crop Breeding Techniques at NDSU. Carena is a native of Buenos Aires, Argentina. http://www.ag.ndsu.nodak.edu/plantsci/faculty/Carena.htm
Book Synopsis The Genetic Architecture of Quantitative Disease Resistance in Maize by : Jesse Abner Poland
Download or read book The Genetic Architecture of Quantitative Disease Resistance in Maize written by Jesse Abner Poland and published by . This book was released on 2010 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Several large scale quantitative genetic studies were conducted to better understand the genetic basis for quantitative disease resistance (QDR) in plants. The focus of these studies was the economically important disease of maize (Zea mays L. ssp. mays), northern leaf blight (NLB, caused by Setosphaeria turcica L. anamorph Exserohilum turcicum). The maize nested association mapping (NAM) population, a reference design population consisting of 4,630 recombinant inbred lines, was evaluated over three environments for quantitative resistance to NLB, giving highly heritable resistance phenotypes. Over 200 resistance alleles at 30 different quantitative trait loci (QTL) for disease resistance were identified. Genome-wide nested association mapping for NLB resistance identified genes at six of the QTL that have been associated with disease resistance including three receptor-like kinases, two ethylene response factors, and one Mlo-like gene. Further insight on QDR, with a focus on multiple disease resistance (MDR), was gained by jointly analyzing independent data on NAM for resistance to southern leaf blight (SLB), gray leaf spot (GLS) and NLB. To examine the possibility of MDR genes, the estimated allele effects from each founder inbred were compared at loci were QTL for two or more diseases co-localized. At seven loci, positively correlated allele effects provided evidence for MDR genes. Analysis of the NAM population suggested that resistance to the three diseases studied here is largely due to the accumulation of disease-specific genes and, to a limited extent, pleiotropic genes that condition MDR. A final study was conducted to determine the effect of variability in visual disease rating on mapping disease QTL by assessing the effects of scorer variability and rating scales on mapping QTL for NLB in a single recombinant inbred line population from NAM. Stepwise general linear model selection (GLM) and inclusive composite interval mapping (ICIM) were used for QTL mapping. For both GLM and ICIM the same QTL were largely found across scorers, though some QTL were only identified by some scorers. Strikingly, the magnitudes of estimated allele effects from different scorers at identified QRL were drastically different, sometime by as much as three fold. The studies conducted here advance the understanding of QDR in plants and lay groundwork for identifying the genes responsible for resistance to NLB in maize. A greater understanding of QDR will assist in the development of durable resistant crop cultivars, improving food security and safety.
Book Synopsis Genetic Analysis of Quantitative Trait Loci with the Early Generations of an Elite, Single-cross Maize Population by : Dwi Asmono
Download or read book Genetic Analysis of Quantitative Trait Loci with the Early Generations of an Elite, Single-cross Maize Population written by Dwi Asmono and published by . This book was released on 1998 with total page 366 pages. Available in PDF, EPUB and Kindle. Book excerpt: Evidence of consistent detection was observed at 27% (25 of 93) of the QTLS. For grain yield and yield components, seventy-one QTLs were detected across samples, only thirteen were common in both samples. Chromosome 6 was significantly associated with grain yield in both samples. The magnitudes of QTL effects were not always consistent when QTLs were detected in a region for both samples. Most QTLs detected in both samples had the same parental effects.
Book Synopsis The Genetic Architecture of Maize Photoperiod Sensitivity as Revealed by Recombinant Inbred Line, Backcross, and Heterogeneous Inbred Family Populations by :
Download or read book The Genetic Architecture of Maize Photoperiod Sensitivity as Revealed by Recombinant Inbred Line, Backcross, and Heterogeneous Inbred Family Populations written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The genetic diversity of elite temperate maize germplasm is very narrow in comparison to the genetic diversity available across of the entire species. Tropical maize germplasm has frequently been cited as a potential source of enhanced genetic diversity that could be used to increase corn productivity. One obstacle to utilizing tropical maize germplasm in temperate breeding programs is photoperiod sensitivity, which is very common in tropical adapted maize lines. An investigation of the quantitative trait loci (QTL) contributing to maize photoperiod sensitivity may increase the facility and ability with which maize breeders can adapt tropical maize germplasm to temperate latitudes. The inductive phase of maize photoperiod sensitivity was studied in a diverse set of temperate and tropical lines. From a factorial mating of two temperate and two tropical inbreds, four populations of recombinant inbred lines (RIL) were developed for the purpose of mapping the QTL underlying photoperiod sensitivity in tropical maize. Plants were grown in both long- and short-day environments and a number of traits were measured in each environment. These traits include flowering time, plant height, leaf number, and ear structure traits. The trait differences between long- and short-day environments were reported as the photoperiodic responses of the RILs. Utilizing the data of both individual and combined mapping populations, QTL were identified using Iterative QTL Mapping (iQTLm). The positions and effects of these QTL were compared between populations and with flowering time and plant height QTL from other mapping studies. We detected four regions in the genome that produced large photoperiod effects and named these ZmPR1, ZmPR2, ZmPR3, and ZmPR4. These four QTL accounted for 75% of the phenotypic diversity for photoperiod measured by our analysis. Similar QTL positions have been detected by other researchers studying photoperiod sensitivity and flowering time in maize. In addition to.
Book Synopsis Identification of Quantitative Trait Loci (QTL) for Gray Leaf Spot Resistance, Maturity, and Grain Yield in a Semi-tropical Recombinant Inbred Population of Maize by :
Download or read book Identification of Quantitative Trait Loci (QTL) for Gray Leaf Spot Resistance, Maturity, and Grain Yield in a Semi-tropical Recombinant Inbred Population of Maize written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Identification of QTL can aide in future breeding objectives by allowing breeders either to improve a line through targeted introgressions or assist in forward breeding strategies. Such analyses may be particularly helpful in integrating exotic germplasm into a breeding program. The percentage of tropical maize germplasm grown in U.S. farmers' fields is almost nonexistent. Tropical germplasm in maize (Zea mays L.) is a valuable resource to decrease the dependence upon a limited genetic base currently used to produce commercial hybrids, extend selection limits for grain yield, and to provide an insurance function against emerging biotic and abiotic stresses. Results of research presented in this dissertation support these recommendations. Experiments were conducted to evaluate 143 S4:5 recombinant inbred lines (RILs) resulting from a cross between NC300, an all-tropical, temperate adapted line, and B104, a stiff stalk line. The 143 RILs were topcrossed to the Lancaster tester FR615xFR697 and randomly subdivided into two sets. The two sets were evaluated for resistance to GLS disease and yielding ability in three and eight North Carolina environments, respectively. Spatial trends were examined in the GLS trials. Significant (P d".01) trend effects were fitted in five of the six set-by-environment combinations, which led to improved analyses within and across environments for both sets. Ninety-three and eighty-two percent of the RILs in topcrosses (RILT) were significantly (P = 0.05) more resistant to GLS when compared to the mean of the commercial checks for set 1 and 2, respectively. Twenty-one RILs from both sets did not differ significantly (P = 0.05) for grain yield when compared to the mean of the commercial checks. RIL 2070 yielded significantly (P = 0.05) higher when compared to one commercial check, HC33. TR7322. RIL 1991 was rated the most resistant entry in set 1 and also did not differ from the mean of the commercial checks for grain yield. The RILs we.
Book Synopsis Genetics, Genomics and Breeding of Maize by : Ramakrishna Wusirika
Download or read book Genetics, Genomics and Breeding of Maize written by Ramakrishna Wusirika and published by CRC Press. This book was released on 2014-08-05 with total page 313 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sequencing of the maize genome has opened up new opportunities in maize breeding, genetics and genomics research. This book highlights modern trends in development of hybrids, analysis of genetic diversity, molecular breeding, comparative and functional genomics, epigenomicsand proteomics in maize. The use of maize in biofuels, phytoremediation and pharmaceuticals is also highlighted. Current research trends, future research directions and challenges are discussed by a panel of experts from all over the world.
Book Synopsis The Maize Genome by : Jeffrey Bennetzen
Download or read book The Maize Genome written by Jeffrey Bennetzen and published by Springer. This book was released on 2018-11-24 with total page 390 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book discusses advances in our understanding of the structure and function of the maize genome since publication of the original B73 reference genome in 2009, and the progress in translating this knowledge into basic biology and trait improvement. Maize is an extremely important crop, providing a large proportion of the world’s human caloric intake and animal feed, and serving as a model species for basic and applied research. The exceptionally high level of genetic diversity within maize presents opportunities and challenges in all aspects of maize genetics, from sequencing and genotyping to linking genotypes to phenotypes. Topics covered in this timely book range from (i) genome sequencing and genotyping techniques, (ii) genome features such as centromeres and epigenetic regulation, (iii) tools and resources available for trait genomics, to (iv) applications of allele mining and genomics-assisted breeding. This book is a valuable resource for researchers and students interested in maize genetics and genomics.
Book Synopsis Quantitative Trait Loci Analysis to Identify Modifiers Genes of the Gene Opaque2 in Maize Endosperm by : Libardo Andres Gutierrez Rojas
Download or read book Quantitative Trait Loci Analysis to Identify Modifiers Genes of the Gene Opaque2 in Maize Endosperm written by Libardo Andres Gutierrez Rojas and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The protein quality of maize can be improved by replacing normal Opaque2 alleles with non-functional recessive alleles opaque2 (o2). The allele o2 produces a severe phenotype with soft endosperm enhancing its protein quality but decreasing its agronomical value. Plant breeders have restored a desirable ratio of hard to soft endosperm in o2 germplasm known as Quality Protein Maize (QPM). Neither the mechanism nor the genetic components by which the modification of the endosperm in QPM lines occurs are well understood. To increase the understanding of the genetics of endosperm modification, a population of 146 recombinant inbred lines derived from a cross between the o2 inbred line B73o2 and the QPM inbred line CML161 was evaluated in two Texas locations from 2004 to 2006. Four traits related to endosperm texture were measured and showed significant effect of the inbred lines, high heritability estimates and high genetic correlations. Relative content of the essential amino acids lysine, tryptophan and methionine were measured and showed significant effects of the lines and considerable high genetic correlations and heritabilities. Negative correlation was observed between endosperm texture traits and amino acid content. Quantitative trait loci (QTL) were mapped for traits related to the modification of endosperm texture and the content of lysine, tryptophan and methionine. QTLs clusters for endosperm texture traits were detected on chromosomes 3, 5, 6 and 8 explaining 62-68% of the variation. QTLs clusters for amino acid contents were located on chromosomes 7 and 8 that explained up to 39% of the observed variation. The product of the O2 gene is a transcription factor that affects the expression of a number of endosperm genes. A group of 29 endosperm genes associated with the O2 activity were evaluated in developing endosperm of the recombinant inbred lines. Genomic regions controlling gene transcript abundance in developing endosperm were identified by expression QTL mapping. Evidence is presented of QTL hot spots that segregate in association with endosperm texture modification or amino acid contents and are associated with the regulation of the expression of a group of endosperm genes.
Book Synopsis Identification of Major Quantitative Trait Loci for Grain Quality Traits in Tropical Maize Recombinant Inbred Lines by : Haci-Murat Arpat
Download or read book Identification of Major Quantitative Trait Loci for Grain Quality Traits in Tropical Maize Recombinant Inbred Lines written by Haci-Murat Arpat and published by . This book was released on 1996 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Genetic Analysis of Ear Length and Correlated Traits in Maize by : Andrew Jon Ross
Download or read book Genetic Analysis of Ear Length and Correlated Traits in Maize written by Andrew Jon Ross and published by . This book was released on 2002 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt: Maize (Zea mays L.) ear length is positively correlated with grain yield. Thirty generations of selection for increased ear length, however, failed to increase grain yield in Iowa Long-Ear Synthetic (BSLE). Negative correlations between ear length and other yield-related traits complicated indirect selection for grain yield. The main objective of this investigation was to identify quantitative trait loci (QTL) that affect the variation of ear length, grain yield, and other ear traits, and the correlations among traits. Secondary objectives were to validate QTL by comparing their genetic positions across generations, environments, and other populations. QTL were mapped in the F2 and F[subscript 2:3] generations of a bi-parental population. The inbred parents differed in ear length by 14 cm, and were derived from the divergent sub-populations of BSLE. More QTL were detected for ear length (16), kernel-row number (12), and kernel depth (6) than detected in prior QTL studies. Eighty percent of the alleles for increased trait values originated from the parent with the higher trait value. Most QTL were validated by one of the three methods. More than 67% of the QTL were identified in at least two F[subscript 2:3] environments. Forty-three percent of the QTL from the F[subscript 2:3] mean environment were previously identified in the F2. Seven QTL for ear length, one for kernel-row number, and two for grain yield seemed to coincide with QTL in other populations. Traits with higher heritabilities generally had more coincidental QTL, and traits with lower heritabilities generally had fewer coincidental QTL. QTL positions and the parental origin of alleles agreed with the direction of the genetic correlation coefficients. The magnitude of the correlations was generally explained by the frequency of QTL that coincided or were genetically linked. Repulsion-phase linkage between ear length and grain yield QTL near the centromere of chromosome 5 may have caused the failure of ear length selection in BSLE to increase grain yield. QTL on chromosome 6 exemplified the genetic basis for the positive correlation between ear length and grain yield.
Book Synopsis Trait Variation and QTL Mapping in Early-Season Maize Populations by : Raja Khanal
Download or read book Trait Variation and QTL Mapping in Early-Season Maize Populations written by Raja Khanal and published by . This book was released on with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis The Maize Handbook by : Michael Freeling
Download or read book The Maize Handbook written by Michael Freeling and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 776 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Maize Handbook represents the collective efforts of the maize research community to enumerate the key steps of standard procedures and to disseminate these protocols for the common good. Although the material in this volume is drawn from experience with maize, many of the procedures, protocols, and descriptions are applicable to other higher plants, particularly to other grasses. The power and resolution of experiments with maize depend on the wide range of specialized genetic techniques and marked stocks; these materials are available today as the culmination of nearly 100 years of genetic research. A major goal of this volume is to introduce this genetical legacy and to highlight current stock construction programs that will soon benefit our work, e. g. high-density RFLP maps, deletion stocks, etc. Both stock construction and maintenance are relatively straightforward in maize as a result of the ease of crossing and the longevity of stored seeds. Crossing is facilitated by the separate staminate (tassel) and pistillate (ear) flowers, a feature almost unique to maize. On the other hand, many of the genetic methodologies utilized with maize, including the precision of record keeping, can be adapted to other plants. Facile communication and a spirit of co-operation have characterized the maize genetics community since its earliest days. Starting in the 1930s, institutions such as annual Maize Genetics Cooperation Newsletter, the Maize Genetics Stock Center, and the annual maize genetics meeting provide continuity to the field.
Book Synopsis Changes in Genetic Variance During Advanced Cycle Breeding in Maize by : Jianming YU
Download or read book Changes in Genetic Variance During Advanced Cycle Breeding in Maize written by Jianming YU and published by . This book was released on 2003 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Petunia written by Tom Gerats and published by Springer Science & Business Media. This book was released on 2008-12-11 with total page 451 pages. Available in PDF, EPUB and Kindle. Book excerpt: Petunia belongs to the family of the Solanaceae and as such is closely related to important crop species like tomato, potato, eggplant, pepper and tobacco. With around 35 species described it is one of the smaller genera and among those there are two groups of species that make up the majority of them: the purple flowered P.integrifolia group and the white flowered P.axillaris group. It is assumed that interspecific hybrids between members of these two groups have laid the foundation for the huge variation in cultivars as selected from the 1830’s onwards. Petunia thus has been a commercially important ornamental since the early days of horticulture. Despite that, Petunia was in use as a research model only parsimoniously until the late fifties of the last century. By then seed companies started to fund academic research, initially with the main aim to develop new color varieties. Besides a moment of glory around 1980 (being elected a promising model system, just prior to the Arabidopsis boom), Petunia has long been a system in the shadow. Up to the early eighties no more then five groups developed classical and biochemical genetics, almost exclusively on flower color genes. Then from the early eighties onward, interest has slowly been growing and nowadays some 20-25 academic groups around the world are using Petunia as their main model system for a variety of research purposes, while a number of smaller and larger companies are developing further new varieties. At present the system is gaining credibility for a number of reasons, a very important one being that it is now generally realized that only comparative biology will reveal the real roots of evolutionary development of processes like pollination syndromes, floral development, scent emission, seed survival strategies and the like. As a system to work with, Petunia combines advantages from several other model species: it is easy to grow, sets abundant seeds, while self- and cross pollination is easy; its lifecycle is four months from seed to seed; plants can be grown very densely, in 1 cm2 plugs and can be rescued easily upon flowering, which makes even huge selection plots easy to handle. Its flowers (and indeed leaves) are relatively large and thus obtaining biochemical samples is no problem. Moreover, transformation and regeneration from leaf disc or protoplast are long established and easy-to-perform procedures. On top of this easiness in culture, Petunia harbors an endogenous, very active transposable element system, which is being used to great advantage in both forward and reverse genetics screens. The virtues of Petunia as a model system have only partly been highlighted. In a first monograph, edited by K. Sink and published in 1984, the emphasis was mainly on taxonomy, morphology, classical and biochemical genetics, cytogenetics, physiology and a number of topical subjects. At that time, little molecular data was available. Taking into account that that first monograph will be offered electronically as a supplement in this upcoming edition, we would like to put the overall emphasis for the second edition on molecular developments and on comparative issues. To this end we propose the underneath set up, where chapters will be brief and topical. Each chapter will present the historical setting of its subject, the comparison with other systems (if available) and the unique progress as made in Petunia. We expect that the second edition of the Petunia monograph will draw a broad readership both in academia and industry and hope that it will contribute to a further expansion in research on this wonderful Solanaceae.
