A QTL for root growth angle on rice chromosome 7 is involved in the genetic pathway of DEEPER ROOTING 1.

Yusaku Uga,Eiji Yamamoto,Noriko Kanno,Shuichi Fukuoka,Sawako Kawai,Yuka Kitomi,Tatsumi Mizubayashi

doi:10.1186/s12284-015-0044-7

Yusaku Uga, Eiji Yamamoto + Show 5 more

Open Access

https://doi.org/10.1186/s12284-015-0044-7

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Abstract

BackgroundRoot growth angle (RGA) is an important trait that influences the ability of rice to avoid drought stress. DEEPER ROOTING 1 (DRO1), which is a major quantitative trait locus (QTL) for RGA, is responsible for the difference in RGA between the shallow-rooting cultivar IR64 and the deep-rooting cultivar Kinandang Patong. However, the RGA differences between these cultivars cannot be fully explained by DRO1. The objective of this study was to identify new QTLs for RGA explaining the difference in RGA between these cultivars.ResultsBy crossing IR64 (which has a non-functional allele of DRO1) with Kinandang Patong (which has a functional allele of DRO1), we developed 26 chromosome segment substitution lines (CSSLs) that carried a particular chromosome segment from Kinandang Patong in the IR64 genetic background. Using these CSSLs, we found only one chromosomal region that was related to RGA: on chromosome 9, which includes DRO1. Using an F2 population derived from a cross between Kinandang Patong and the Dro1-NIL (near isogenic line), which had a functional DRO1 allele in the IR64 genetic background, we identified a new QTL for RGA (DRO3) on the long arm of chromosome 7.ConclusionsDRO3 may only affect RGA in plants with a functional DRO1 allele, suggesting that DRO3 is involved in the DRO1 genetic pathway.Electronic supplementary materialThe online version of this article (doi:10.1186/s12284-015-0044-7) contains supplementary material, which is available to authorized users.

Highlights

Root growth angle (RGA) is an important trait that influences the ability of rice to avoid drought stress
Evaluation of deep rooting in the IK-chromosome segment substitution lines (CSSLs) We developed a set of 26 CSSLs derived from a cross between IR64 and Kinandang Patong (Figure 1)
Only plants of SL1020, which was homozygous for Kinandang Patong throughout chromosome 9 and which contained functional allele of DEEPER ROOTING 1 (DRO1), had a significantly larger mean ratio of deep rooting (RDR; 53.4%) than that of IR64 (7.8%), the RDR in this line was significantly smaller than that in Kinandang Patong (73.7%) (Figure 2)

Summary

Introduction

Root growth angle (RGA) is an important trait that influences the ability of rice to avoid drought stress. DEEPER ROOTING 1 (DRO1), which is a major quantitative trait locus (QTL) for RGA, is responsible for the difference in RGA between the shallow-rooting cultivar IR64 and the deep-rooting cultivar Kinandang Patong. Our research group has reported three major rice QTLs for RGA, namely DRO1 (DEEPER ROOTING 1), DRO2, and qSOR1 (quantitative trait locus for SOIL SURFACE ROOTING 1), in three different mapping populations (Uga et al 2011, 2012, 2013b). DRO1 has been detected on chromosome 9 in recombinant inbred lines (IK-RILs) derived from a cross between the shallow-rooting cultivar IR64 and the deep-rooting cultivar Kinandang Patong (Uga et al 2011).

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