Molecular breeding

About: Molecular breeding is a research topic. Over the lifetime, 2120 publications have been published within this topic receiving 56908 citations.

Impacts of nucleotide fixation during soybean domestication and improvement

Abstract: Plant domestication involves complex morphological and physiological modification of wild species to meet human needs. Artificial selection during soybean domestication and improvement results in substantial phenotypic divergence between wild and cultivated soybeans. Strong selective pressure on beneficial phenotypes could cause nucleotide fixations in the founder population of soybean cultivars in quite a short time. Analysis of available sequencing accessions estimates that ~5.3 million single nucleotide variations reach saturation in cultivars, and then ~9.8 million in soybean germplasm. Selective sweeps defined by loss of genetic diversity reveal 2,255 and 1,051 genes were involved in domestication and subsequent improvement, respectively. Both processes introduced ~0.1 million nucleotide fixations, which contributed to the divergence of wild and cultivated soybeans. Meta-analysis of reported quantitative trait loci (QTL) and selective signals with nucleotide fixation identifies a series of putative candidate genes responsible for 13 agronomically important traits. Nucleotide fixation mediated by artificial selection affected diverse molecular functions and biological reactions that associated with soybean morphological and physiological changes. Of them, plant-pathogen interactions are of particular relevance as selective nucleotide fixations happened in disease resistance genes, cyclic nucleotide-gated ion channels and terpene synthases. Our analysis provides insights into the impacts of nucleotide fixation during soybean domestication and improvement, which would facilitate future QTL mapping and molecular breeding practice.

Mutation Breeding in Ornamentals

Abstract: Induced mutation technique is a valuable tool that has been exploited for ornamental breeding for the past 30 years. Mutation breeding has been more successful in ornamental plants because changes in phenotypic characteristics like flower color, shape and size, chlorophyll variegation in leaves, and growth habit can be easily detected. In addition, the heterozygous nature of many ornamental plants offers high mutation frequency. Since mutations are induced in single cells, irradiation of multicellular structures with chemical and physical mutagens will appear as chimeras. However, the use of in vitro culture using adventitious bud techniques has proven to be the most efficient method to avoid chimerism. Mutation by using X-rays and gamma rays has successfully produced a large number of new varieties in different ornamental plants which had been commercialized. Appropriate strategies in mutation induction such as the use of in vitro culture technique in combination with chronic gamma irradiation have proven to be an effective method of mutation induction to produce new promising mutant varieties of ornamentals over a short period of time. During the past two decades, ion beam radiation has emerged as an effective and unique mutagen for improvement in ornamental plants since it produces higher mutation frequencies compared to X-rays and gamma rays. Currently, interest in research has shifted toward the application of molecular breeding and genetic engineering for ornamental improvement, but both have their own advantages and disadvantages. Mutation breeding is still an attractive method for creating genetic variability and has become a routine technique in many vegetatively propagated ornamental plants.

Recent Advances in Molecular Breeding of Cassava For Improved Drought Stress Tolerance

Abstract: Cassava is an important tropical starchy root crop that is used extensively in drought prone tropical regions. It responds to water deficit with a dehydration avoidance and growth arrest syndrome. Carbohydrate is supplied from stems via remobilization. It is very limited in its use of osmotic adjustment, compatible solute synthesis, dehydrin accumulation and other tolerance mechanisms for low water potential. Given the difficulties of conventional breeding of cassava due to its long breeding cycle, heterozygousity, and difficulties in producing seed, an important recent development is the use of molecular markers and marker assisted selection (MAS). MAS is also contributing to the introgression of traits from wild relatives

Breeding soybeans with resistance to soybean rust (Phakopsora pachyrhizi)

Abstract: Soybean rust, caused by the fungal pathogen Phakopsora pachyrhizi, continues to be a global threat to soybean production, decreasing productivity and increasing the pesticide burden of cropping systems. However, breeders now have access to resistance genes that map to at least seven independent loci which can help protect crops against soybean rust infection. Efficient greenhouse screening protocols have been developed, and low‐cost SNP genotyping technology is available for marker‐assisted selection and backcrossing of resistance to Phakopsora pachyrhizi (Rpp) loci. Soybean breeders can now employ these technologies for the development of high‐yielding soybean cultivars with two, three, or even four pyramided Rpp genes. Such cultivars should provide resistance against the most virulent P. pachyrhizi populations and would be of great help to both large‐scale growers in the Americas and subsistence farmers in developing countries. We hope that a better understanding of the history and unique characteristics of P. pachyrhizi, the discovery of Rpp resistance alleles and the latest molecular breeding techniques will empower breeders across the globe to develop cultivars with durable resistance.