Hybrid rice exploits the phenomenon of hetrosis which can increase the yield potential over hyvs. Hybrid rice and heterosis breeding 1 types of heterosis 1 how is heterosis measured. Heterosis or hybrid vigor, on the other hand, is the tendency of outbred strains to exceed both inbred parents in fitness. Click download or read online button to get manual for hybrid rice seed production book now. Studies conducted at the international rice research institute irri during 1980 and 1981 have shown up to 73% heterosis, 59% heterobeltiosis and 34% stan. Overdominant epistatic loci are the primary genetic basis. Heterosis is the base of the great success in hybrid rice. Heterosis and inheritance of fertilityrestorer genes in rice jakkrit seesang, prapa sripichitt, tanee sreewongchai department of agronomy, faculty of agriculture, kasetsart university, bangkok 10900 thailand corresponding author, email. Utilization of heterosis has contributed tremendously to the increased productivity in many crops for decades. Although there have been a range of studies on various aspects of heterosis, the key to understanding the biological mechanisms of heterotic performance in crop hybrids is the genetic basis, much of which. We developed an innovative hybrid rice breeding strategy that uses the monogenic recessive. To build predictive models for rice hybrids under different growth conditions, we measured the grain yield of two f 1 hybrid populations pop2012 and pop2015 and calculated betterparent heterosis for yield per plant bphypp for subsequent analysis table s1.
Hybrids have been widely used in crop and tree breeding since ancient times, although the molecular mechanisms underlying heterosis have yet. Determination of predictive variables for yield heterosis. Dissecting combining ability effect in a rice nciiiii. Heterosis or hybrid vigour is a phenomenon in which hybrid progeny exhibit superior yield and biomass to parental lines and has been used to breed f1 hybrid cultivars in many crops. The latter was estimated in comparison to commercial varieties. Experimental research station of plant breeding, university of hohenheim, maize and sunflower 5. We conclude that indepth unlocking of genetic variations among oryza species will further enhance rice breeding. Presence of exploitable heterosis and sound seed production techniques are the prerequisites for success of hybrid rice breeding programme while these. Heterosis refers to the superior performance of hybrids relative to the parents. The ypps of parents from the two populations were significantly. The book contains a wealth of useful information for practicing hybrid rice breeders, seed producers, researchers, and students of.
First, most qtl associated with inbreeding depression and heterosis in rice appeared to be involved in epistasis. The identification of qtls and hls for yield and yieldrelated traits provide useful information for hybrid rice breeding, and help to uncover the genetic basis of rice heterosis. The genomics of oryza species provides insights into rice. In this study, heterosis levels among groups of parental lines were investigated for three reasons. The bonus from heterosis should be approximately 5% for production and 10% for mortality, fertility, health and survival. Metabolomebased prediction of yield heterosis contributes to the breeding of elite rice zhiwu dan, yunping chen, weibo zhao, qiong wang, wenchao huang improvement of the breeding ef. To breed an ideal cross with the highest grain yield and great stress resistance is the ultimate goal of hybrid rice breeders. Now, the acreage of hybrid rice takes more than half of the total rice area in china and superior hybrid rice has been showing a increasing contribution to the grain yield normile, 2008. Divergent selection and genetic introgression shape the. Manual for hybrid rice seed production download ebook.
Determination of heterotic groups and heterosis analysis. Hybrid rice is now a viable commercial product in countries such as china and india that rely on this plant as their major food cereal. Inbreeding may or may not lead to inbreeding depression, which is a reduction in the fitness in the offspring produced by inbred matings. Insights into the genomic architecture of heterosis for grain yield in rice are presented, and further mapping of grain yield loci resolves candidate genes that could be useful for breeding. These observations tend to implicate epistasis and overdominance, rather than dominance, as the major genetic basis of heterosis in rice. Research on heterosis, male sterility systems, outcrossing mechanisms. Heterosis and hybrid rice breeding sant singh virmani. Comparative transcriptional profiling and preliminary. Heterosis studies for yield and its components in rice hybrids.
Heterosis and combining ability analysis for yield and quality traits in. Pdf for practical exploitation of hybrid vigor in rice, emasculation is a major constraint. M t, manalo j o 1997 hybrid rice breeding manual, 151. Despite the great contributions of utilizing heterosis to crop productivity worldwide, the molecular mechanism of heterosis remains largely unexplored. The converse or complement to inbreeding depression in which the value d a inbreeding can result in loss of vigor, size, etc. Heterosis refers to the phenomenon that progeny of diverse varieties of a species or crosses between species exhibit greater biomass, speed of development, and fertility than both parents. Heterosis is a term used in genetics and breeding and is also known as hybrid vigor.
It is selfpollinated crop but a certain extent of cross pollination may take place. Shull, while working as a corn geneticist at the cold spring harbor laboratory from 1904 to 1915, observed that when two different purebred lines of corn were crossbred the resulting progeny exhibited physical traits superior to those of the. Physiological bases of heterosis and crop management strategies for. When two homozygous inbreeds a true breeding line obtained by continuous inbreeding of genetically unlike constituents are crossed together, the resulting hybrids obtained from. Here, by genome analysis, we found that breeders introduced different introgressed exogenous genomes of other rice subpopulations to construct male and female parents. The term heterosis, often used synonymously with hybrid vigor, refers to the superiority of the f 1 hybrid over its parents. Genetic composition of yield heterosis in an elite rice. Neuware this is a reference book which describes importance, use and basic information relevant to application of heterosis breeding in tomato for yield and quality contributing traits. Integrated genomic approaches have efficiently investigated many heterotic loci in hybrid rice underlying yield heterosis advantages and revealed the genomic architecture of rice heterosis. Provided here is a concise account of hybrid breeding in rice, a newly deployed breeding approach to increase the yield.
The application of heterosis hybrid vigor in hybrid rice since the 1970s has tremendously improved rice productivity worldwide. Hybrid rice breeding manual books international rice research. A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext. In addition to the heterosis of aboveground agronomic traits on which most existing studies have focused, root heterosis is also an indispensable component of heterosis in the entire plant and of major importance to plant breeding. Rice is the most important food crop of the developing world and the demand for it is growing. Heterosis breeding in rice for quantitative traits 545 82.
Hybrid vigor or heterosis is defined as a superior performance of hybrids, for many traits, relative to their parental inbred lines see chapter 8 of this book. Plant and animal breeders exploit heterosis by mating two different purebred lines that have certain desirable traits. Thus, the present research is focused on the grain number heterosis of a widely used latecropping indica super hybrid rice combination in china using a highthroughput. To systematically exploit heterosis in hybrid breeding. Heterotic grouping and its importance in tropical hybrid rice breeding srijan ambati thakur virender jeet singh department of genetics and plant breeding, college of agriculture, professor jayashankar telangana state agricultural university, hyderabad. Ppt heterosis powerpoint presentation free to view. Studies conducted at the international rice research institute irri during 1980 and 1981 have shown up to 73% heterosis, 59% heterobeltiosis and 34% standard heterosis for yield in rice. Ir36 and ir42 yield 45 tha in wet season trials and 78 tha in dry season trials. In this article we will discuss about heterosis or hybrid vigour. Heterosis is a major yield factor in all breeding categories except line breeding schnell, 1982. George harrison shull, working with corn at the station for experimental evolution at cold harbor, studied the effects of crossbreeding and summarized his results in 1910.
Abstract heterosis and heterotic patterns are important factors exploited to the most. Heterosis and inheritance of fertilityrestorer genes in rice. Exploitation of heterosis loci for yield and yield. In fact, enhanced heterosis greater than 40% observed at irri in indicatropical japonica crosses encouraged us to develop cms lines in the genetic background of elite tj lines possessing wide compatibility wc genes. Second, most 90% qtl contributing to heterosis appeared to be overdominant. Hybrids have been widely used in crop and tree breeding since ancient times, although the molecular mechanisms underlying heterosis have yet to be fully elucidated.
Consequently, systematic investigations of root heterosis, particularly in reproductivestage rice, are needed. Heterosis breeding is the one of the strongest tool for breeder to complete targated demand of 2030 as rice is self pollinated species male sterility is essential for hybrid rice production. Despite the accumulation of data on the genetic and molecular understanding of heterosis, there is little information on the regulation of heterosis at the physiological level. Transcriptome analysis of rice root heterosis by rnaseq. Various models have been posited to explain heterosis, including dominance, overdominance, and pseudooverdominance. In this perspective, we consider that it might be useful to the field to abandon these. If true, it should not be possible to obtain an inbred that performs equally as well as the best hybrid bernardo 2002 breeding for quantitative traits in plants pp 243246. Inbreeding depression loss or decrease in vigor due to inbreeding.
Genomic architecture of heterosis for yield traits in rice. Heterosis has been commercially exploited in rice with a yield advantage of 20 25%. In this study, we performed a quantitative analysis of endogenous gibberellin ga content and expression profiling of the ga metabolism and signaling genes to investigate the possible relationship between ga signaling. After maize hybrid was first utilized in field on a large scale in usa in 1930s, heterosis of other crops such as rice, sorghum, rape, and vegetable etc began to be widely used in production, and had made great achievements in crop breeding by the end of last century, mainly contributed to notable increasing of crop yield. But how breeders construct hybrid parents to obtain hybrid rice heterosis remains unclear. Heterosis, the increase in such characteristics as size, growth rate, fertility, and yield of a hybrid organism over those of its parents. Experimental details the two cytoplasmic male sterile cms lines viz. A free powerpoint ppt presentation displayed as a flash slide show on id. Heterosis, heterobeltiosis, rice hybrid, standard heterosis and wacms. Selective breeding of plants and animals, including hybridization, began long before there was an understanding of underlying scientific principles. Inbreeding depression results due to fixation of unfavourable recessive genes in f2. Heterosis is an additional gain above the average genetic level of the two parent breeds. Heterosis definition types of heterosis heterosis in. Heterosis breeding and inbreeding depression authorstream.
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