Abstract
Earlier we identified wheat (Triticum aestivum L.) chromosome 3A as a major determinant of grain yield and its component traits. In the present study, a high-density genetic linkage map of 81 chromosome 3A-specific markers was developed to increase the precision of previously identified yield component QTLs, and to map QTLs for biomass-related traits. Many of the previously identified QTLs for yield and its component traits were confirmed and were localized to narrower intervals. Four novel QTLs one each for shoot biomass (Xcfa2262-Xbcd366), total biomass (wPt2740-Xcfa2076), kernels/spike (KPS) (Xwmc664-Xbarc67), and Pseudocercosporella induced lodging (PsIL) were also detected. The major QTLs identified for grain yield (GY), KPS, grain volume weight (GVWT) and spikes per square meter (SPSM) respectively explained 23.2%, 24.2%, 20.5% and 20.2% of the phenotypic variation. Comparison of the genetic map with the integrated physical map allowed estimation of recombination frequency in the regions of interest and suggested that QTLs for grain yield detected in the marker intervals Xcdo549-Xbarc310 and Xpsp3047-Xbarc356 reside in the high-recombination regions, thus should be amenable to map-based cloning. On the other hand, QTLs for KPS and SPSM flanked by markers Xwmc664 and Xwmc489 mapped in the low-recombination region thus are not suitable for map-based cloning. Comparisons with the rice (Oryza sativa L.) genomic DNA sequence identified 11 candidate genes (CGs) for yield and yield related QTLs of which chromosomal location of two (CKX2 and GID2-like) was confirmed using wheat aneuploids. This study provides necessary information to perform high-resolution mapping for map-based cloning and for CG-based cloning of yield QTLs.
Highlights
Grain yield is one of the most important targets for agricultural research, as well as for sustaining human and livestock populations on this planet
Greenhouse Evaluation of Traits In view of accessing reliability and the applied value of phenotypic measurements made on the complex traits under the controlled environment, and to evaluate 95 recombinant inbred chromosome lines (RICLs) 3A-population for plant biomass-related traits, data were recorded on the following traits: root biomass (RB), Shoot biomass (SB), TB, plant height (PH), heading date (HD), The 1000-kernel weight (TKW), Seed weight per spike (SWPS) and kernels per spike (KPS)
Most of the traits scored in this study had coefficient of variation (CV) values,15% with an exception of RB that had 29% CV
Summary
Grain yield is one of the most important targets for agricultural research, as well as for sustaining human and livestock populations on this planet. Grain yield in wheat (Triticum aestivum L.) can be largely partitioned into three major components: kernel number per spike, kernel weight, and spikes or reproductive tillers per unit area These traits are affected by other traits including anthesis date, plant biomass, and plant height. Objectives of the present study were to: i) increase the marker density of the 3A map to localize QTLs to narrower intervals; ii) identify QTLs for biomass related traits including root and shoot biomass in wheat, and iii) identify rice genomic regions corresponding with the QTL-containing regions of wheat to identify additional markers and genes putatively underlying the QTLs. we intended to compare number and quality of QTLs identified from greenhouse evaluation with that from multi-location field trials, and effect of increasing the marker number with plant number on the efficacy of QTL detection and resolution
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