Genetic Analysis of Root and Shoot Traits in the ‘Essex’ By ‘Forrest’ Recombinant Inbred Line (RIL) Population of Soybean [Glycine max (L.) Merr.]

Abstract

Crop productivity is severely reduced by water deficit and drought in many plant species including soybean. Improved root and shoot traits can contribute to drought tolerance ability of the plant. This research was conducted to identify QTL that underlie several root and shoot traits in the ‘Essex’ by ‘Forrest’ (ExF RILs, n=94) recombinant inbred line (RIL) soybean population. Field collected samples were used for gathering phenotypic data of basal root thickness (BRT), lateral root number (LRN), maximum root length (MRL), root fresh weight (RFW), root dry weight (RDW), shoot fresh weight (SFW), shoot dry weight (SDW), and calculating RFW/SFW, and RDW/SDW ratios. All traits and ratios were compared against DNA markers using the composite interval mapping (CIM). A total of 12 QTL: 3 for MRL, 1 QTL for LRN, 1 QTL for BRT, 2 QTL for RFW, 2 QTL for RDW, 4 QTL for SFW, 3 QTL for SDW, and 3 QTL for SFW/SDW were identified and mapped on different linkage groups (LGs) A2, B2, C2, D1a, F, G, and N. The LOD scores of these QTL ranged from 2.5 to 6.0. No QTL were associated with RFW/RDW. The root and shoot trait QTL of this study may benefit breeding programs for producing cultivars tolerant to water deficit and high yield. Preliminary analyses of genes the QTL regions using GO annotation gave insight into genes that may underlie some of these QTLs.

Characterization of Genetic Basis on Synergistic Interactions between Root Architecture and Biological Nitrogen Fixation in Soybean

“…It has been reported that RA traits could be dramatically influenced by growth stage and environmental factors, such as aerenchyma formation was a result of flooding ( Chimungu et al, 2015 ), which may affect soil exploration by plant roots ( Shimamura et al, 2010 ) and further indirectly influence QTL identification for RA and BNF traits. For example, nine RA QTLs in soybean have been identified under field conditions ( Brensha et al, 2012 ), but with plants that had been grown in pots for 3 weeks before being transferred into field plots. None of these QTLs is consistent with any QTL identified here.…”

Evaluation of high yielding soybean germplasm under water limitation

“…In most crop plants, genetic variations exist for RSA, which enables successful mapping of quantitative trait loci (QTLs) and identification of genes associated with root traits (Prince et al ). Most root studies in soybean have utilized bi‐parental mapping populations to map QTLs for root traits in the seedling stage in controlled greenhouse conditions (Liang et al ; Zhou et al ; Brensha et al ; Liang et al ; Manavalan et al ; Prince et al ) with the exception of a study aimed at mapping QTLs for fibrous root score for plants grown in the field (Abdel‐Haleem et al ). Studying root traits of mature plants is important due to varied responses to soil and climatic conditions when compared to the seedling stage in controlled conditions (Watt et al ).…”

Understanding genetic control of root system architecture in soybean: Insights into the genetic basis of lateral root number

“…Traditional soybean mapping studies have identified numerous root quantitative trait loci (QTL; Abdel-Haleem, Lee, & Boerma, 2011;Brensha et al, 2012;Kassem et al, 2006;Manavalan et al, 2015;Prince, Song, et al, 2015;Rong et al, 2011), but few have identified underlying genes within the detected QTLs (Brensha et al, 2012;Manavalan et al, 2015;Prince, Song, et al, 2015). However, the identification of genes involved in specific biological processes and the subsequent categorization of functional effects on RSA are lacking in soybean.…”

“…The number and thickness of lateral roots were associated with soybean performance in water-deficit soils that represent different target growing environments (Prince, Murphy, et al, 2015). So far, no genes responsible for lateral root number (LRN) have been cloned in soybean, although some QTLs have been mapped (Brensha et al, 2017;Manavalan et al, 2015;Prince, Song, et al, 2015). The formation of a lateral root is a major determinant of a plant's RSA (Pérez-Torres et al, 2008) and this is regulated by auxin signalling (Satbhai, Ristova, & Busch, 2015), surrounding cell wall properties (Péret et al, 2009;Roycewicz & Malamy, 2014).…”