NCED OE rootstocks mostly down-regulate auxin signalling
An antagonistic interaction between ABA and auxin modulates the lateral root developmental program in Arabidopsis (De Smet et al. 2003),Medicago truncatula (Gifford, Dean, Gutierrez, Coruzzi & Birnbaum 2008; Ariel, Diet, Crespi & Chan 2010) and peanuts (Guo, Chen, Wang, Xiao & Chen 2012). ABA induces root tip expression of the auxin transporter genes AUX1 and PIN2 , activating proton secretion, thereby promoting primary root elongation and root hair development under moderate water deficit (Xu et al. 2013). NCED OE rootstocks downregulated most auxin-responsive and auxin-induced genes (ARFs , MYBs , SAURs ) and the auxin transporterPIN9 ( Solyc10g078370), while upregulating the auxin deactivation gene IAASGH3 (Solyc02g064830) in SP12 (qRT-PCR data) (Figure 7e), without changing root IAA concentration (Figure 4). These changes modulate stress-dependent ABA-auxin interactions, thereby decreasing lateral and main root development (Shkolnik-Inbar & Bar-Zvi 2010; Duanet al. 2013; Hong, Seah & Xu 2013; Song & Liu 2015; Ma et al. 2018) as observed in the whole plants under control conditions (Martínez-Andújar et al. 2020b).