Advanced Quantitative Genetics Technologies for Accelerating Plant Breeding

Abstract

Plant breeding is the science that deals with improving the genetic architecture of crop plants for benefit of human beings. Increasing food demand with rising world population, changing food habits and changing climate adversely affecting the plant growth requires accelerating plant breeding activities. Most of the traits in the different growth phases of a plant are quantitative and complex in nature. These traits show continuous distribution of phenotypes in segregating populations and are controlled by number of genes, environment and their interaction. The branch of quantitative genetics aims to understand and manipulate these traits for improving the crop plants. The classical methods to study quantitative traits include the partitioning of total phenotypic variation into environmental and different components of genetic variation. It was also possible to predict the number of genes controlling a quantitative trait in the form of “K-factors” and “effective factors”. Though these methods helped to decide appropriate plant breeding strategy and response to selection, the number, location and specific action of factors (genes) controlling quantitative traits remained obscure. With the advent of molecular markers, new avenues opened up to determine the location of such genes in the form of quantitative trait loci (QTL) by developing different kinds of mapping populations. However mapping and cloning of QTL was still an arduous task due to time involved in development of mapping populations and utilization of molecular markers in scanning the whole genome. The advancements in the field of sequencing, high-throughput genotyping and phenotyping accelerated the mapping and cloning of QTL and their utilization in plant breeding programme through marker-assisted and/or genomic selection. This chapter will discuss the various strategies that advanced the science of quantitative genetics in the past one and half decade and its role in accelerating crop improvement programmes.