Plant breeding

About: Plant breeding is a research topic. Over the lifetime, 3406 publications have been published within this topic receiving 78934 citations.

Molecular markers in plant breeding

Abstract: s ince Mendel's discoxeries more than a century ago, people ha,,e been monitoring, inducm,.z, and mappimz sin,.z, le eene markers in hmher plants. A elance at the v, ell-populated linkage maps of crops such as tomato or maize proxldes convincing e,,idence c,f the anloutl[ of work thai has been focused oil this area of research. Uniil the last 10 to 15 .,,'ears, most of the singlc gene markers used m higher plant genetics were those affecting morphological characters. Common example<, are genes causing dwarfism, chlorophyll deficiencies or altered leaf morphoh',gy. Though these markers have serx ed v, ell m ', arious types of basic and applied research, their use in many areas of plant breeding has been ,,ery limned. The de,,elopment m recent ,,'ears of protein and DNA marker,, offers the possibility of dexeloping new approaches to breeding procedures. The purpose of this article is to revie',~ some of tile present uses of molecular markers m plato breeding and to speculate about future applications. Tile greater ullhty of molecular markers derixes from 5 inherent properties that disiingtiish them fronl morphological markers. (1) Genotypes of molecular loci can be determined at the v, hole plant, tissue, and cellular levels. Phenot.\\'pes of most morphological markers can only be distinguished at the v, hole plant level. (2) A relati,.ely large number of r, aturally occurring alleles can be found at molecular marker loci. Distlngmqmble alleles at morphological marker loci occur lets frequently and often muq be induced through the application of exogenous mutagens. (3) U,mallv no deleterious effects are associated with alternate alleles of molecular markers. This is not the case with morphological markers, v.hich are often accompamed by undesirable phenotypic effects. (4) Alleles of most molecular markers are codommant, allov, ing all possible genoiypes to be distinguished in an.,,' segregating generation. Alleles at morphological marker loci usually interact m a dominant-recessixe manner, prohibiting their t|'.,e in rnany crosses. (5) With morphological marker loci, strong epistatic effects limit the nt, mber of segregating markers that can be unequi,.ocally scored in the same segregating generation. Fewer epistatic or pleiotropic effects are observed with molecular markers, thus a virtually limitless number of segregating markers can be monitored in a tingle population. Based on the level at v, hich the genes are detected, molecular markers can be dpdded into two classe~-protein markers and DNA markers.

Principle and application of plant mutagenesis in crop improvement: a review

Abstract: The first step in plant breeding is to identify suitable genotypes containing the desired genes among existing varieties, or to create one if it is not found in nature. In nature, variation occurs mainly as a result of mutations and without it, plant breeding would be impossible. In this context, the major aim in mutation-based breeding is to develop and improve well-adapted plant varieties by modifying one or two major traits to increase their productivity or quality. Both physical and chemical mutagenesis is used in inducing mutations in seeds and other planting materials. Then, selection for agronomic traits is done in the first generation, whereby most mutant lines may be discarded. The agronomic traits are confirmed in the second and third generations through evident phenotypic stability, while other evaluations are carried out in the subsequent generations. Finally, only the mutant lines with desirable traits are selected as a new variety or as a parent line for cross breeding. New varieties...