Conventional Breeding Methods Widely used to Improve Self-Pollinated Crops
Temesgen Begna, G Acquaah, N Alexandratos, R Allard, P Hansche, B Collard, D Mackill, D Biradar, L Mcmurphy, C Taets, A Rayburn, J Birchler, F Breseghello, A Coelho, F Briggs, R Allard, C Brim, M Chang, E Coe, L Chen, J Bian, S Shi, J Yu, H Khanzada, G Wassan, C Zhu, X Luo, S Tong, X Yang, X Peng, M Cooper, S Fukai, G Pantuwan, B Jongdee, J De Toledo, H Pooni, J Jinks, S Edmands, H Feaman, J Harrison, C Timmerman, W Fehr, A Torres-Penaranda, C Reitmeier, L Wilson, J Narvel, Y Fu, J Gaskin, G Wheeler, M Purcell, G Taylor, P Gepts, B Goulet, F Roda, R Hopkins, M Govindaraj, A Kanatti, K Radhika, V Padma, P Janila, K Rai, J Grafius, G Hodnett, A Hale, D Packer, D Stelly, J Da Silva, W Rooney, D Hoisington, M Khairallah, T Reeves, J Ribaut, B Skovmand, S Taba, M Warburton, H Innan, Y Kim, J, Ni, P Colowit, D Mackill, G Jensen, D Miller, N Jensen, G John, C Jara, J Cuasquer, G Castellanos, E Kok, J Keijer, G Kleter, H Kuiper, C Lee, D Agrawal, C Wang, S Yu, J Chen, H Tsay, J Lee, D Zhu
Abstract
Plant breeding defined as a science and technology of improving the genetic make-up of crop plants in relation to their economic use for the man kind. Conventional plant breeding is the improvement of cultivars using conservative tools for manipulating plant genome within the natural genetic boundaries of the species. Plant breeding is a complex process in which new crop varieties are continuously being developed to improve yield and agronomic performance over current varieties. Plant breeding is considered as the current phase of crop evolution. Mendel's work in genetics ushered in the scientific age of plant breeding. A wide array of naturally occurring genetic changes are sources of new characteristics available to plant breeders. During conventional plant breeding, genetic material is exchanged that has the potential to beneficially or adversely affect plant characteristics. For this reason, commercial-scale breeders have implemented extensive plant selection practices to identify the top-performing candidates with the desired characteristics while minimizing the advancement of unintended changes. Plant breeding efficiency relies mainly on genetic diversity and selection to release new cultivars. The number of genes that control the trait of interest is important to breeders. Qualitative traits controlled by one or a few genes are easier to breed than quantitative traits controlled by numerous genes. Breeders use methods and techniques that are based on the mode of reproduction of the species self-pollinating, cross-pollinating, or clonally propagated. The general strategy is to breed a cultivar whose genetic purity and productivity can be sustained by its natural mating system. The common methods for breeding self-pollinated crop species include mass selection, pure line selection, pedigree, bulk population, single seed descent and backcrossing. The problems associated with classical breeding methods are longer time required to develop resistance cultivars, more effort and labor requirements, transfer of no desirable genes along with resistance genes by hybridization, resistance breakdown due to development of new pathogen races, no availability of resistance sources, and less understanding of the mechanism of resistance in conventional methods. In classical breeding, selections were made on morphological bases that were highly influenced by the environment. This created confusion in selection of desirable parents for breeding programs. Therefore, there was a need to develop new and efficient modern methods to overcome the above-mentioned problems. Generally, the goal of both genetically modified and conventional plant breeding is to produce crops with improved characteristics by changing their genetic makeup. Genetically modified achieves this by adding a new gene or genes to the genome of a crop plant whereas conventional breeding achieves it by crossing together plants with relevant characteristics, and selecting the offspring with the desired combination of characteristics, as a result of particular combinations of genes inherited from the two parents. Both conventional plant breeding and genetically modified deliver genetic crop improvement. Genetic improvement has been a central pillar of improved agricultural productivity for thousands of years. With the development of molecular marker technology in the 1980s, the fate of plant breeding has changed. Different types of molecular markers have been developed and advancement in sequencing technologies has geared crop improvement.