Exploring Natural Allelic Variations of the \u03b2-Triketone Herbicide Resistance Gene HIS1 for Application in indica Rice and Particularly in Two-Line Hybrid Rice

Qiming Lv,Xiuli Zhang,Ducai Liu,Li Tang,Lang Pan,Zuren Li,Lifeng Wang,Rui Peng,Ye Shao,Bigang Mao,Bingran Zhao,Lianyang Bai,Yeyun Xin,Zhiyuan Huang,Dingyang Yuan,Xiaomao Zhou,Lihuang Zhu,Jiming Peng

doi:10.1186/s12284-020-00448-7

Abstract

BackgroundBenzobicyclon (BBC) is a β-triketone herbicide (bTH) used in rice paddy fields. It has the advantages of high efficiency, low toxicity, high crop safety, and good environmental compatibility, and shows efficacy against paddy weeds resistant to other types of herbicides. However, as some important indica rice varieties are susceptible to BBC, BBC is currently only registered and applied in japonica rice cultivation areas.ResultsBy analyzing haplotypes of the bTHs broad-spectrum resistance gene HIS1 and phenotypes for BBC in 493 major indica rice accessions in China, we identified a novel non-functional allelic variant of HIS1 in addition to the previously reported 28-bp deletion. Through detection with markers specific to the two non-functional mutations, it was clear that 25.4% of indica conventional varieties, 59.9% of fertility restorers, and 15.9% of sterile lines were susceptible to BBC. In addition, due to natural allelic variations of the HIS1 gene in the sterile and restorer lines, some two-line hybrid sterile lines were sensitive to bTHs, and the corresponding restorers were resistant. We showed the potential effectiveness of using bTHs to address the issue of two-line hybrid rice seed purity stemming from the self-crossing of sterile lines during hybrid rice seed production. Finally, allelic variations of the HIS1 gene may also play an important role in the mechanized seed production of hybrid rice.ConclusionsOur findings offer guidance for the application of BBC in indica rice areas and provide a non-transgenic approach to address the seed purity issue of two-line hybrid rice.

Highlights

Benzobicyclon (BBC) is a β-triketone herbicide used in rice paddy fields
Benzobicyclon (BBC) is a novel paddy-bleaching βtriketone herbicide (Komatsubara et al 2009) that can be applied from pre-emergence to early postemergence in paddy fields, showing broad-spectrum resistance against annual grasses, sedges, and broadleaf weeds but being harmless to transplanted rice (TPR) and direct seeding of rice (DSR) (Bi et al 2018; Komatsubara et al 2009; Maeda et al 2019). bTHs mainly target 4-hydroxyphenylpyruvate dioxygenase (HPPD), a key enzyme in the biosynthesis of plastoquinone and tocopherol (Kraehmer et al 2014; Moran 2005)
As an herbicide that inhibits HPPD, BBC differs from herbicides that inhibit acetolactate synthetase (ALS) and acetyl-CoA carboxylase (ACCase), which are widely used in paddy fields (Jabusch and Tjeerdema 2005; Kumar and Ladha 2011; Mahajan et al 2013), and BBC can be used as a rotation herbicide in these fields

Summary

Introduction

Benzobicyclon (BBC) is a β-triketone herbicide (bTH) used in rice paddy fields. It has the advantages of high efficiency, low toxicity, high crop safety, and good environmental compatibility, and shows efficacy against paddy weeds resistant to other types of herbicides. Benzobicyclon (BBC) is a novel paddy-bleaching βtriketone herbicide (bTH) (Komatsubara et al 2009) that can be applied from pre-emergence to early postemergence in paddy fields, showing broad-spectrum resistance against annual grasses, sedges, and broadleaf weeds but being harmless to TPR and DSR (Bi et al 2018; Komatsubara et al 2009; Maeda et al 2019). The number of weed species with resistance to herbicides that inhibit HPPD is minimal (Gould et al 2018), and BBC shows efficacy against paddy weeds resistant to other types of herbicide, including sulfonylureas (Maeda et al 2019)

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