Chromosomal Location of Wheat Quantitative Trait Loci Affecting Agronomic Performance of Seven Traits, Using Reciprocal Chromosome Substitutions

Abstract

A major limitation to the genetic improvement of wheat (Triticum aestivum L.) is the lack of information about quantitative trait loci (QTLs). The objective of this study was to determine the chromosomal locations of QTLs controlling grain yield and yield components, grain test weight, plant height, and anthesis date. Reciprocal sets of chromosome substitution lines in duplicate between two hard red winter wheat cultivars, Cheyenne (CNN) and Wichita (WI), were used to identify the chromosomes bearing QTLs. Field trials were conducted in Nebraska at Lincoln in 1987, at Lincoln, Mead, and Alliance in 1988, and at Lincoln, Mead, Alliance, and North Platte in 1989. Wichita had major QTLs on chromosomes 3A and 6A that increased grain yield in Cheyenne and major QTLs on chromosome 36 that decreased grain yield in Cheyenne, while Cheyenne had major QTLs on chromosomes 3A and 6A that decreased grain yield in Wichita. The increase in grain yield by WI 3A and WI 6A was due to a significant increase in seed weight. The decrease in grain yield by CNN 3A and CNN 6A was due to a significant decrease in culms per square meter. The decrease in grain yield by WI 3B was due to a significant decrease in winterhardiness, resulting in decreased seed weight and culms per square meter. We identified one Wichita and seven Cheyenne chromosomes with QTLs affecting seeds per culm, seven Wichita and five Cheyenne chromosomes with QTLs affecting seed weight, one Wichita and three Cheyenne chromosomes with QTLs affecting culms per square meter, and one or more chromosomes with QTLs affecting each of the other agronomic traits.

Understanding grain yield: it is a journey, not a destination

“…To do this Berke et al (1992a) evaluated the reciprocal chromosome lines in the major ecological zones of Nebraska (Peterson 1992). Because the lines were developed by backcrossing, each substitution line was made in duplicate with the understanding that any random effect due to backcrossing of importance could be measured by comparing the duplicate lines for the same substitution.…”

“…Their similarity was later confirmed using DArT markers by Dr. Rustgi. Hence, though there were 21 chromosome substitution lines for each background (21 for CNN and 21 for WI), Berke et al (1992a), actually evaluated 84 + substitution lines due to some were at different levels of backcrossing, and most were BC 6 . In this research, chromosomes 3A and 6A were found to be the two most important chromosomes affecting grain yield.…”

“…The presence of genes with small effects is clear from the study of Buckler et al (2009). In addition, while CNN(WI3A), CNN(WI6A), and CNN(WI3B) were significantly different from CNN and WI(CNN(3A) and WI(CNN6A) were significantly different from WI for grain yield, in reviewing the grain yield data from Berke et al (1992a), 18 of the WI chromosome substitution lines in CNN background were higher yielding than CNN. Only three WI chromosome substitution lines in CNN background were lower yielding than CNN which is very unlikely to have occurred by chance alone if the substitution lines have the same mean yield as CNN.…”

Advanced backcross QTL analysis in progenies derived from a cross between a German elite winter wheat variety and a synthetic wheat (Triticum aestivumL.)

“…The study of QTLs in wheat has a long history and is based on the use of morphological markers with cytogenetically derived single chromosome substitution lines (Berke et al 1992;Law 1966Law , 1967Law et al 1978;Snape et al 1985). However, QTLs can only be located onto individual chromosomes using this method, while the employment of molecular markers enables the researcher to map QTLs to specific chromosomal regions.…”

Inter-varietal chromosome substitution lines in wheat — revisited

“…For many of the substitutions into Chinese Spring, such as Hope, for example, either five or six backcrosses were used (Kuspira & Unrau, 1957). The reciprocal substitutions of Cheyenne and Wichita underwent six to seven backcrosses (Berke et al, 1992). The substitutions of Bezostaya 1 into CappelleDesprez, mentioned later, have each undergone eight backcrosses.…”