Quantitative Trait Loci (QTL) involved
Studies have been conducted in different plants such as rice (Y. Kim et al., 2020), grain legumes (Ye et al., 2018) and wheat (C. Li et al., 2021) where they have reported different QTL and genes produced in drought stress. Ranjan et al., (2022) has reported QTL, mRNAs, genes and transcription factors that actively take part in response of RSA to water stress. Among these various root traits, dry weight of root and root length harbors maximum gene number that are expressed in response to drought. For example, under drought QTL such as PRL3, PRL2, CRL1, SRL2, SRL7, SRL9, and QTRL.cgb-3B are associated with root length in maize (T. Li et al., 2017) and wheat (X. Liu et al., 2013) respectively. Likewise in wheat, Qrdws.uwa-4AL and Qrdws.uwa-5AL are known to be associated with root dry weight in wheat (Ayalew et al., 2017) and in sorghum QTLs qRDW1_2, qRDW1_5, and qRDW1_8 are linked to root dry weight (Mace et al., 2012). In rice, overexpression of OsNAC5 (Jeong et al., 2013) and OsNAC10 (Jeong et al., 2010) were reported to enhance the root diameter in drought stress. Kawai et al., (2022) has recently reported that under mild drought conditions, QHB and OsWOX10 are responsible for regulating diameter of lateral roots in rice. InBrassica napus , a gene BnaC03g45915D (ortholog of A. thaliana gene RD29B) is found to be present within QTL qR/S-13-1 and showed increased expression in dry conditions configuring plants to adapt to drought conditions more efficiently (Prerostova et al., 2018). Analysis of QTL that are associated with physiological and morphological traits w.r.t drought tolerance helps to develop understanding about the genetic architecture involved in drought responses and how it can be utilized to produce crops that are well adapted to drought.