Molecular breeding

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

Status and Opportunities of Molecular Breeding Approaches for Genetic Improvement of Tea

Abstract: Tea is the most popular perennial plantation crop in the Southeast Asian countries because of its attractive aroma, taste, and health benefits. Tea plantations provides an important agro-based, eco-friendly employment generating and export oriented industries in all the tea-growing countries. However, the future of tea industry depends on the availability of high-yielding and high-quality tea clones with greater tolerance to pest, diseases, and environmental stresses. Genetic improvement of tea involves identification, characterization, evaluation, domestication, maintenance, and utilization of germplasm for the development of superior plant material. Conventional breeding program in tea is, however, limited by long gestation period, outbreeding nature, and self-incompatibility. This chapter summarizes the status of emerging molecular genomic information that can expedite the genetic improvement in tea and hence the productivity too. This will also provide a background for possibilities of modern tea breeding together with some current efforts for the development of sequence-based markers such as microsatellites, single-nucleotide polymorphisms (SNPs) and links genetic diversity of existing gene pools for the identification of diverse parental groups and efficient phenotyping to support operational breeding. Preliminary attempts on quantitative trait locus (QTL) mapping in tea were also reviewed, and prospectives are also provided on power of association genetics to dissect quantitative traits. Challenges and opportunities to integrate advancement and advent of next-generation sequencing (NGS) technologies to generate genome-wide makers and to integrate genomic information into directional selective breeding are also discussed.

Capsicum Breeding: History and Development

Abstract: Capsicum or chili peppers were predominantly domesticated first in America and was introduced from there to rest of the world by Columbus. Capsicum breeding initially started as selection from wild species for different purposes and further improvement was based on the art of selection. With time, the breeding for crop improvement became more scientific and classical methods like mass selection, pedigree method, single-seed descent method, backcross, and hybridization are currently being utilized for capsicum improvement. Genetic diversity of capsicum is large, allowing alternatives to several new gene rearrangements. Capsicum fruits have high nutritional value, bringing benefits to consumer’s health. This fact has contributed to increase the market and consumption of capsicum in the world. Search for capsicum genotypes with increased yield, disease and abiotic stress resistance and improved quality is the goal in capsicum breeding programs. Lately, new strategies for improvement like mutation breeding, polyploidy, haploid breeding, embryo rescue, and utilization of molecular markers have been used in capsicum breeding. With continuous advancement in molecular technologies, it is becoming an essential tool which when combined with traditional selection and crossing techniques can result in significant progress in already established capsicum genetic breeding program.

Genetic and phenotypic characterization of rice grain quality traits to define research strategies for improving rice milling, appearance, and cooking qualities in Latin America and the Caribbean.

Abstract: Rice (Oryza sativa L.)grain quality is a set of complex interrelated traits that include grain milling, appearance, cooking, and edible properties. As consumer preferences in Latin America and the Caribbean evolve, determining what traits best capture regional grain quality preferences is fundamental for breeding and cultivar release. In this study, a genome-wide association study (GWAS), marker-assisted selection (MAS), and genomic selection (GS) were evaluated to help guide the development of new breeding strategies for rice grain quality improvement. For this purpose, 284 rice lines representing over 20 yr of breeding in Latin America and the Caribbean were genotyped and phenotyped for 10 different traits including grain milling, appearance, cooking, and edible quality traits. Genetic correlations among the 10 traits ranged from -0.83 to 0.85. A GWAS identified 19 significant marker/trait combinations associated with eight grain quality traits. Four functional markers, three located in the Waxy and one in the starch synthase IIa genes, were significantly associated with six grain-quality traits. These markers individually explained 51-75% of the phenotypic variance depending on the trait, clearly indicating their potential utility for MAS. Cross-validation studies to evaluate predictive abilities of four different GS models for each of the 10 quality traits were conducted and predictive abilities ranged from 0.3 to 0.72. Overall, the machine learning model random forest had the highest predictive abilities and was especially effective for traits where large effect quantitative trait loci were identified. This study provides the foundation for deploying effective molecular breeding strategies for grain quality in Latin American rice breeding programs.

Research Progress on Cloning and Function of Xa Genes Against Rice Bacterial Blight

Abstract: Bacterial blight (BB) of rice caused by Xanthomonas oryzae pv. oryzae (Xoo) is one of the most serious bacterial diseases that hinder the normal growth and production of rice, which greatly reduces the quality and yield of rice. The effect of traditional methods such as chemical control is often not ideal. A series of production practices have shown that among the numerous methods for BB controlling, breeding and using resistant varieties are the most economical, effective, and environmentally friendly, and the important basis for BB resistance breeding is the exploration of resistance genes and their functional research. So far, 44 rice BB resistance genes have been identified and confirmed by international registration or reported in journals, of which 15 have been successfully cloned and characterized. In this paper, research progress in recent years is reviewed mainly on the identification, map-based cloning, molecular resistance mechanism, and application in rice breeding of these BB resistance genes, and the future influence and direction of the remained research for rice BB resistance breeding are also prospected.