Genetic dissection of QTLs associated with spikelet-related traits and grain size in sorghum

Abstract

Although spikelet-related traits such as size of anther, spikelet, style, and stigma are associated with sexual reproduction in grasses, no QTLs have been reported in sorghum. Additionally, there are only a few reports on sorghum QTLs related to grain size, such as grain length, width, and thickness. In this study, we performed QTL analyses of nine spikelet-related traits (length of sessile spikelet, pedicellate spikelet, pedicel, anther, style, and stigma; width of sessile spikelet and stigma; and stigma pigmentation) and six grain-related traits (length, width, thickness, length/width ratio, length/thickness ratio, and width/thickness ratio) using sorghum recombinant inbred lines. We identified 36 and 7 QTLs for spikelet-related traits and grain-related traits, respectively, and found that most sorghum spikelet organ length- and width-related traits were partially controlled by the dwarf genes Dw1 and Dw3. Conversely, we found that these Dw genes were not strongly involved in the regulation of grain size. The QTLs identified in this study aid in understanding the genetic basis of spikelet- and grain-related traits in sorghum.

DOMINANT AWN INHIBITORencodes the ALOG protein originating from gene duplication and inhibits awn elongation by suppressing cell proliferation and elongation in sorghum

“…We previously demonstrated that the combination of BTx623 and NOG is useful for dissecting various traits, such as those related to the photosynthetic capacity during grain filling (Ohnishi et al 2019), biomass (Kajiya-Kanegae et al 2020), spikelet morphology (Takanashi et al 2021), organophosphate pesticide sensitivity (Jing et al 2021), and seed ionome (Wahinya et al 2022). Using this population, we cloned DAI , which is present only in BTx623 because of gene duplication.…”

“…Previously, we identified two dominant QTLs that control plant height using the same RILs, which corresponded to Dw1 and Dw3 . These two loci were shown to pleiotropically influence the size of spikelet-related organs, such as SSs, pedicels, anthers, and styles in the same RIL population (Takanashi et al 2021). Considering that NOG has functional alleles for both genes (Kajiya-Kanegae et al 2020), qAL7 and qAL9 detected in this study likely correspond to Dw3 and Dw1 , respectively.…”

“…In addition, sorghum is a suitable genetic model for C4 grasses because of its high morphological diversity and relatively small genome size (approximately 732 Mb) compared to those of other C4 grasses (Price et al 2005, Paterson et al 2009, McCormick et al 2018). In our recent study, we used a next-generation sequencing approach, restriction site-associated DNA sequencing (RAD-seq), combined with the use of recombinant inbred lines (RILs) derived from a cross between BTx623 and Japanese Takakibi NOG to establish a high-density genetic map that allowed for the investigation of important traits by detecting quantitative trait loci (QTLs) (Kajiya-Kanegae et al 2020, Jing et al 2021, Takanashi et al 2021, Wahinya et al 2022). We predicted that awn development can also be investigated as the parents used in the RILs displayed contrasting awn morphologies.…”

Genetic Architecture of Grain Yield-Related Traits in Sorghum and Maize

“…Genetic changes in other grain yield-related traits have also accumulated to feed the world. A case in point is that grain number per panicle of both sorghum and maize cultivars increased more than their wild progenitors [ 34 , 35 , 36 ]. Bommert et al reported that grain number per panicle was negatively correlated with grain size and some other inflorescence architectures [ 37 ].…”

“…To date, over 168 primarily mapped QTLs associated with grain size have been reported in sorghum. Among them, 155 QTLs located on ten chromosomes have been mapped for thousand grain weight (TGW) in various independent studies published between 1995 and 2021 [ 13 , 34 , 43 , 45 , 46 , 47 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 ] ( Figure 1 a and Table S1 ). Few QTLs related to grain size (21 QTLs for grain length, 23 QTLs for grain width, and 26 QTLs for grain number per panicle) have been identified.…”