QTL analysis of internode elongation in response to gibberellin in deepwater rice.

K Nagai,R B Angeles-Shim,T Noda,M Ashikari,A Yoshimura,T Kuroha,H Yasui,T Kitaoka,Y Kondo

doi:10.1093/aobpla/plu028

Abstract

Gibberellin (GA) is a plant hormone that has important roles in numerous plant developmental phases. Rice plants known as deepwater rice respond to flooding by elongating their internodes to avoid anoxia. Previous studies reported that GA is essential for internode elongation in deepwater rice. Quantitative trait locus (QTL) analyses identified QTLs regulating internode elongation in response to deepwater conditions. However, the interaction between internode elongation and regulators of GA sensitivity in deepwater rice is unknown. In this study, we applied GA to recombinant inbred lines of T65 (non-deepwater rice) and Bhadua (deepwater rice), and performed a QTL analysis of internode elongation in response to GA. GA-induced internode elongation was detected only in deepwater rice. Our QTL analysis revealed two major QTLs on chromosomes 3 and 9 regulating total internode length, lowest elongated internode and number of elongated internodes. Furthermore, the QTL on chromosome 3 acted as an enhancer of other QTLs (e.g. the QTL on chromosome 12). Nearly isogenic lines of deepwater rice carrying the QTL regions from chromosomes 3 and 12 of the deepwater rice C9285 showed internode elongation in response to GA. Thus, these QTLs may regulate GA responsiveness in deepwater rice. This study furthers our understanding of the mechanism of internode elongation in rice.

Highlights

The plant hormone gibberellin (GA) regulates many aspects of plant growth, organ development and environmental responses (Achard and Genschik 2009)
After treatment with 1024 M GA + 1026 M uni or 1026 M uni for 3 weeks, we measured the length of the second leaf sheaths and total internode length (TIL) (Fig. 1A– C)
Bhadua and C9285 showed significant internode elongation in response to GA, but Taichung 65 (T65) and Nipponbare did not (Fig. 1C). These results suggest the presence of factors controlling internode elongation in response to GA in deepwater rice

Summary

Introduction

The plant hormone gibberellin (GA) regulates many aspects of plant growth, organ development and environmental responses (Achard and Genschik 2009). GA was initially identified to be involved in the phenomenon of stem and leaf elongation (Hori 1898; Sawada 1912; Kurosawa 1926). In this process of elongation, GA is associated with the regulation of cell division and cell elongation. In non-deepwater rice, GA biosynthesis and signalling occur in elongating and dividing organs and tissues, such as the shoot apex and young leaves (Kaneko et al 2003). Rice plants known as deepwater rice can induce internode elongation during vegetative

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Conclusion