QTL Mapping of Six Spike and Stem Traits in Hybrid Population of Agropyron Gaertn. in Multiple Environments

Abstract

Most Agropyron Gaertn. species are excellent sources of forage. The derivative lines of wheat-Agropyron cristatum show elite agronomic traits, and some are valuable for wheat breeding. The species of Agropyron Gaertn. was mainly recognized by the spike morphology in traditional taxon. Six traits, including spike length (SL), ear stem length (ESL), the second internodes length (SIL), spikelet number per spike (SNS), floret number per spikelet (FNS), and grain number per spikelet (GNS), are vital to morphology studies and also influences the forage crop yield. To elucidate the genetic basis of spike and stem traits, a quantitative trait locus (QTL) analysis was conducted in a cross-pollinated (CP) hybrid population derived from a cross between two diverse parents, Agropyron mongolicum Keng Z2098 and A. cristatum (L.) Gaertn. Z1842, evaluated across three ecotopes (Langfang, Changli, and Guyuan of Hebei, China) over 3 years (from 2014 to 2016). Construction of a high-density linkage map was based on 1,023 single-nucleotide polymorphism (SNP) markers, covering 907.8 cM of the whole Agropyron genome. A total of 306 QTLs with single QTL in different environments explaining 0.07–33.21% of the phenotypic variation were detected for study traits. Seven major-effect QTLs were identified, including one for ESL on chromosome 3, one for SIL on chromosome 5, three for SL (two on chromosome 2 and one on chromosome 4), and two for SNS on chromosomes 3 and 7. Also, seven stable QTLs, including four for ESL, one for SL, one for GNS, and one for FNS, were mainly mapped on chromosomes 2, 3, 4, 5, and 7, respectively, elucidating 0.25–14.98% of the phenotypic variations. On the use of Agropyron CP hybrid population to identify QTL determining spike and stem traits for the first time, these QTLs for six traits would provide a theoretical reference for the molecular marker-assisted selection in the improvement of forage and cereal crop species.

Identification and Validation of a Novel Locus Controlling Spikelet Number in Bread Wheat (Triticum aestivum L.)

“…In the present study, by assessing two spikelet number-related traits TSN and FSN in a DH population among five environments, we found that TSN and FSN were significantly and positively correlated with GNS (Table 2) with a high heritability (0.85 for TSN and 0.82 for FSN) ( Table 1). The results were consistent with previous knowledge (Che et al, 2018;Würschum et al, 2018;Zhang et al, 2019) that they are environmentally stable yield components and mainly determined by genetic factors. Therefore, increasing spikelet number could be considered as an effective strategy for increasing GNS and hence the grain yield.…”

Dynamic QTL mapping for plant height in the hybrid population of Agropyron Gaertn.

“…Tillering ramets from individual F 1 population obtained by crossing between A. mongolicum Z2098 (female) and A. cristatum Z1842 (male) and parents, a total of 115 individuals (including two parents), were transplanted to two different locations, that is Changli campus plots and the farm of Hebei Normal University of Science and Technology, in April 2013 (Che et al, 2018). Conventional field management practices were used at farm study sites.…”

“…When the p value of the marker was less than the threshold, it was considered that there was a trait‐related QTL at the marker. A QTL with an LOD value >2.5 and a contribution rate of >10% detected in different environments was defined as a major QTL, and the QTL detected in at least three different environments was regarded as a stable QTL (Che et al, 2018; Fan et al, 2015; Wang, 2009). The QTL was named according to the method described by Mccouch et al (1997).…”

“…The QTL of six spike and stem traits in the CP (cross‐pollination) hybrid population of A. Gaertn. derived from a cross between A. mongolicum and A. cristatum in multiple environments was mapped (Che et al, 2018). Based on the same CP hybrid population of A.…”

Four-Year and Five-Developing-Stage Dynamic QTL Mapping for Tiller Number in the Hybrid Population of Agropyron Gaertn.

“…constructed using a CP population that contains 1,023 markers on seven linkage groups, with a total of 907.8 cm and an average distance of 1.5 cm between adjacent loci (Zhang et al, 2015). Based on this map, the major and stable QTL for plant height (PH; Che et al, 2020) and QTL for other characteristics of the spike (Che et al, 2018) in A. Gaertn. have been detected.…”