Root angle modifications by the DRO1 homolog improve rice yields in saline paddy fields

Abstract

The root system architecture (RSA) of crops can affect their production, particularly in abiotic stress conditions, such as with drought, waterlogging, and salinity. Salinity is a growing problem worldwide that negatively impacts on crop productivity, and it is believed that yields could be improved if RSAs that enabled plants to avoid saline conditions were identified. Here, we have demonstrated, through the cloning and characterization of qSOR1 (quantitative trait locus for SOIL SURFACE ROOTING 1), that a shallower root growth angle (RGA) could enhance rice yields in saline paddies. qSOR1 is negatively regulated by auxin, predominantly expressed in root columella cells, and involved in the gravitropic responses of roots. qSOR1 was found to be a homolog of DRO1 (DEEPER ROOTING 1), which is known to control RGA. CRISPR-Cas9 assays revealed that other DRO1 homologs were also involved in RGA. Introgression lines with combinations of gain-of-function and loss-of-function alleles in qSOR1 and DRO1 demonstrated four different RSAs (ultra-shallow, shallow, intermediate, and deep rooting), suggesting that natural alleles of the DRO1 homologs could be utilized to control RSA variations in rice. In saline paddies, near-isogenic lines carrying the qSOR1 loss-of-function allele had soil-surface roots (SOR) that enabled rice to avoid the reducing stresses of saline soils, resulting in increased yields compared to the parental cultivars without SOR. Our findings suggest that DRO1 homologs are valuable targets for RSA breeding and could lead to improved rice production in environments characterized by abiotic stress.

Intricate genetic variation networks control the adventitious root growth angle in apple

“…Natural variations involving auxin signalling and gravitropism contributed to genetic diversity in the RGA During root formation and development processes, auxin regulates the gravitropic set-point angles by adjusting the magnitude of the anti-gravitropic offset component via TIR1/AFB-Aux/IAA-ARF-dependent auxin signalling within the gravity-sensing cells of the roots [82]. Some functional genes, DRO1, LAZY1 and qSOR1, which regulate root gravitropism by auxin signalling, are closely associated with RGA [7,41,83]. In this study, 153 DEGs involved in gravitropism, auxin signalling, and related pathways were detected by RNA-seq.…”

“…Natural variation of the RGA has been reported, but the genetic basis for this variation is largely unknown [9,10,61,66]. Introgression lines in rice demonstrated that combinations of allelic variations in qSOR1 and DRO1 controlled the RGA in rice [83]. To date, little is known about genetic variation in apple RGAs.…”

Exploiting Natural Variation in Crown Root Traits via Genome-Wide Association Studies in Maize

“…Its expression is negatively regulated by auxin and the encoded protein helps mediate root tip cell elongations related to asymmetrical root growth and the downward bending of the root in response to gravity [4]. A previous study con rmed that qSOR1, which is a DRO1 homologue, is also negatively regulated by auxin, and is predominantly expressed in root columella cells to in uence root gravitropic responses [20]. All of these genes are potential targets for root system architecture (RSA)-related breeding.…”

Synergy Between a Shallow Root System With a DRO1 Homologue and Localized P Application Improves Rice P Uptake 

“…The Dro1-NIL, developed by Uga et al 16 , has a relatively deep RGA with the combination of functional alleles of both DRO1 and qSOR1. The qsor1-NIL, developed by Kitomi et al 17 , has a shallower RGA than IR64, with the combination of nonfunctional alleles of both DRO1 and qSOR1. We hypothesize that P-dipping, creating the P hotspot at the soil surface, will have a positive interaction with the shallow root system in rice.…”