Guangfeng Chen

Molecular Markers of Quality Traits and Their Applications

With the development of economics and people’s living level, wheat quality becomes more and more important. The improvement of wheat quality is considered as an important goal in wheat breeding. Like yield traits, molecular markers have been used in selecting wheat quality.

Conditional QTL Mapping of Major Quality Traits

Till now many gene/QTL for wheat grain protein content have been previously identified, but the effects of these QTLs belonged to the cumulative effects of mature. So it couldn’t explain the dynamic expression of QTL during the development of protein synthesis.

Molecular Markers of Yield Traits and Their Application

The yield and its related traits are quantitative traits, which are controlled by major and minor genes and are affected by environments (Asins et al. in Plant Breed 121:281–291, 2002; Huang et al. in 106:1379–1389, 2003). Many researches carried out QTL mapping of wheat yield and its related traits using different populations. Although many major QTLs were obtained, the molecular markers linked with the yield are less found, even the application.

The Technology Roadmap by MAS

The program of conventional breeding generally contains selecting parents, arranging the hybrid combination, the heterosis of F1 detection, strain selection from F2 to F5 generations, new strains out of breeding garden to participate in kinds of new lines comparison test, etc. In China, a new variety bred and released needs about 10 years.

Roles of Conditional QTL in Crop Breeding and Cultivation

The invention and application of molecular markers, especially PCR technique, have provided crucial technical support for the transition from traditional crop breeding to molecular breeding. Accordingly, combined with the bioinformatics, a novel concept, namely “breeding by design,” was proposed in 2003 by a Belgium scientist. The main contents of this concept are based on QTL mapping of a genetic population, QTL effect analysis, and QTL interactive effect on breeding by design.

Concept and Research Contents of Conditional QTL Mapping

QTLs analysis for wheat yield, quality, and physiology and anti-resistance traits were researched in this book Volume 1 by using the final phenotype data at mature or final development stages. However, it is well known that, during plant morphogenesis, plant development will go through the processes from short to tall, small immature grain to large grain size, from young to mature, during which doughtiness, low/high temperature, disease and many other adverse environmental factors can occur in addition to various improper agricultural practices (e.g., over-irrigation and/or-fertilization). These unfavorable factors would negatively affect interrelations between grain yield components (e.g., spike number/plant, grain number/spike and grain weight) and grain quality.

The Concept and Research Progress of MAS

New crop variety breeding was conducted with the development of scientific innovation of human civilization (Table 5.1). From 10,000 years ago, humans had begun to collect some crops, and then transferred to large-scale production in traditional agriculture. Generations of ancestors have left us rich and colorful landraces, which would help us to create some new cultivars.

Exploration of Molecular Markers and Creation of Molecular Breeding Elements

Molecular marker-assisted breeding is highly based on the development of high-performance molecular markers, which is a kind of genetic marker. Genetic markers are indicators that can be used to trace the movement of particular chromosome, a chromosome segment, or some gene loci in a breeding family.

Molecular Markers of Resistance Traits and Their Applications

It is well known that the wheat resistance traits such as drought resistance, salt tolerance, water logging, and disease resistance are controlled by multigenes. The expression of these genes is easily affected by environments.

Molecular Markers of Physiological Traits and Their Applications

Compared with agronomic and yield traits, there are few researches on QTL mapping of physiological traits and molecular markers’ application. However, QTL mapping of physiological traits is becoming more and more in recent 10 years because physiological traits play an important role for crop growth and development.