Mapping QTL, Selection Differentials, and the Effect of Rht‐B1 under Organic and Conventionally Managed Systems in the Attila × CDC Go Spring Wheat Mapping Population

Abstract

1129 RESEARCH M any wheat (Triticum aestivum L.) breeding objectives for organically managed systems (including grain yield, resistance to abiotic and biotic stresses, and baking quality) are similar to conventionally managed systems. It may be, however, necessary to test the expression of these traits under low input, very weedy organic conditions to maximize gain from selection in organic environments. A few traits relevant to high input farming may have negative effects on organic lands. The breeding for semidwarf wheat cultivars as a result of the green revolution has resulted in (i) reduced depth and size of root systems, (ii) increased reliance on N fertilizers to attain satisfactory protein content, (iii) ABSTRACT A randomly derived recombinant inbred line (RIL) population (n = 163) from a cross between CIMMYT spring wheat 'Attila' and the Canadian 'CDC Go' was used to map quantitative trait loci (QTL) affecting various agronomic and quality traits. The experiment was also designed to investigate the feasibility of organic wheat breeding by determining selection differentials and the effect of Rht-B1 in paired organic and conventional management systems. Heritability estimates differed between systems for five of nine traits measured; including grain yield, number of tillers, plant height, kernel weight, and grain protein content. Direct selection in each management system resulted in 50% or fewer selected individuals in common between the two systems, for eight of the nine (except for flowering time) studied traits. Most QTL were specific to either the organic or the conventional management system. However, consistent QTL for grain yield, grain volume weight, kernel weight, and days to flowering were mapped in both systems on chromosomes 6A, 1B, 3A, and 5B, respectively. The effect of Rht-B1 was more pronounced in organic systems, where RILs carrying the wild-type allele were taller, produced more grain yield with higher grain protein content, and suppressed weed biomass to a greater extent than those carrying dwarfing alleles. Results of the present study suggest that differences exist between the two management systems for QTL effects. Indirect selection of superior genotypes from one system to another will not result in the advancement of the best possible genotypes. Therefore, selection of spring wheat cultivars for organic systems should be conducted on organically managed lands.

QTL detection for wheat kernel size and quality and the responses of these traits to low nitrogen stress

“…Ceccarelli and Grando (1991) have reported that the best lines selected in low-yield environments outperform superior lines selected in high-yield environments. In addition, the indirect selection efficiency of superior genotypes is trait dependent, and indirect selection can lead to greater genetic gains than direct selection for highly heritable traits (Hill et al 1998;Asif et al 2015). In this study, the Spearman's rank correlation coefficient between the treatments for TKW was second to that for KL among the 11 traits investigated (Table 2; Fig.…”

“…QKh-2D.1 and QTw-2D might have been identified due to the presence of other linked genes. The Rht-B1 gene is associated with physiological processes that affect not only plant height but also yield, grain quality, seedling vigor and adaptability to adverse environments (Fischer and Stockman 1986;Gooding et al 1999Gooding et al , 2012McCartney et al 2006;Zheng et al 2010;Bai et al 2013;Zhang et al 2013;Asif et al 2015). This study indicated that Rht-B1b had negative effects on TKW, KW, KDR, TW, DT, and ZEL.…”

“…The measurements were calibrated using calibration samples according to the manufacturer's instructions. Previous studies have confirmed that NIRS is a powerful method for measuring the quality traits of wheat; that it is rapid, effective, and convenient compared with traditional methods; and that it is appropriate for use in wheat breeding programs designed to improve quality-related traits (Sourdille et al 1996;Perretant et al 2000;Turner et al 2004;Kuchel et al 2006;Nelson et al 2006;Li et al 2009Li et al , 2012Mann et al 2009;Suprayogi et al 2009;Sun et al 2010;Asif et al 2015).…”

“…A recent study has shown that direct selection in a conventional and organic management system (selection intensity of up to a 15 %) resultes in the selection of 50 % or fewer RILs with common yield-and quality-related traits (Asif et al 2015). Ceccarelli and Grando (1991) have reported that the best lines selected in low-yield environments outperform superior lines selected in high-yield environments.…”

Organic versus Conventional Cropping Sustainability: A Comparative System Analysis

“…However extensive gene mapping and identification of valuable quantitative trait loci (QTL) are required, which is mostly available for major crops. Asif et al [137] recently determined that most QTLs in wheat were developed specifically to either conventional or organic management environments and that some loci did not respond similarly under different environmental pressures. This method of selection has demonstrated great success when building pest resistance through gene pyramiding for conventional systems.…”