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Title: Genome-wide genetic dissection of supernumerary spikelet and related traits in common wheat

item ECHEVERRY-SOLARTE, MORGAN - North Dakota State University
item KUMAR, AJAY - North Dakota State University
item Kianian, Shahryar
item MANTOVANI, EDER - North Dakota State University
item SIMSEK, SENAY - North Dakota State University
item ALAMARI, MOHAMMED - King Saud University
item MERGOUM, MOHAMED - North Dakota State University

Submitted to: The Plant Genome
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/9/2014
Publication Date: 12/1/2016
Citation: Echeverry-Solarte, M., Kumar, A., Kianian, S., Mantovani, E.E., Simsek, S., Alamari, M., Mergoum, M. 2016. Genome-wide genetic dissection of supernumerary spikelet and related traits in common wheat. The Plant Genome. 7(3):1-16.

Interpretive Summary: In order to improve cultivate wheat, exotic germplasm are looked at for traits of importance. In this study an exotic line carrying genes for increased number of florets and seeds was analyzed. This study identifed a number of genes related to number of spikeletes per spike, spike density, number of spikeletes per node, number of nodes per spike with supernumerary spikelet, number of nodes with extended rachillas, and number of nodes per spike without supernumerary spikeletes. A number of regions across the genome were identified that influence multiple traits simultaneously. Stable genes that contribute significantly to important agronomic traits as related to grain number and yield identified in the present study may be useful in marker assisted breeding programs to transfer the desirable alleles into elite wheat germplasm.

Technical Abstract: Branched spike or supernumerary spikelet (SS) is a naturally occurring variant in wheat and holds great potential for increasing the number of grains per spike, and ultimately, increasing wheat yield. However, detailed knowledge of the molecular basis of spike branching in common wheat is lacking. In the present study, a recombinant inbred line (RIL) population derived from the cross of an SS accession and an elite non-SS line was developed and evaluated over four to six environments for seven SS-related traits to identify the genetic basis of SS in wheat. A framework linkage map was generated using 939 diversity arrays technology (DArT) markers. Composite interval mapping (CIM) identified a total of seven consistent quantitative trait loci (QTL) located on five chromosomes (2D, 5B, 6A, 6B, and 7B), suggesting a polygenic inheritance of SS. The phenotypic variation explained (PVE) by individual QTL ranged from 3.3 to 37.3%. The QTL located on 2D (QSS.ndsu-2D) and 7B (QSS.ndsu-7B.2) have major effects (PVE > 15%), while the remaining five QTL (QSS.ndsu-5B, QSS.ndsu-6A, QSS.ndsu-6B.1, QSS.ndsu-6B.2, QSS.ndsu-7B.1) have minor effects (PVE < 15%). Comparison of the genomic locations of the QTL suggested that QSS.ndsu-2D was located in the same regions on 2DS, where QTL for several traits have been reported. However, the remaining six QTL for SS are reported for the first time. Multiple interval mapping (MIM) showed that all seven QTL are involved in epistatic interaction. The major genomic regions controlling these SS-related traits may prove invaluable for wheat improvement and could also be the target for future studies aimed at cloning these genes.