Significant achievements have been made in breeding programs for the heavy-panicle-type (HPT)rice (Oryza sativa) in Southwest China.The HPT varieties now exhibit excellent lodging resistance,allowing them to overcome the greater pressures caused by heavy panicles.However,the genetic mechanism of this lodging resistance remains elusive.Here,we isolated a major quantitative trait locus,Panicle Neck Diameter 1 (PND1),and identified the causal gene as GRAIN NUMBER 1A/CYTOKININ OXlDASE 2 (Gn1A/OsCKX2).The null gn1a allele from rice line R498 (gn1aR498) improved lodging resistance through increasing the culm di-ameter and promoting crown root development.Loss-of-function of Gn1a/OsCKX2 led to cytokinin accumulation in the crown root tip and accelerated the development of adventitious roots.Gene pyr-amiding between the null gn1aR498 allele with two gain-of-function alleles,STRONG CULM 2 (SCM2)and SCM3,further improved lodging resistance.Moreover,Gn1a/OsCKX2 had minimal influence on overall rice quality.Our research thus highlights the distinct genetic components of lodging resistance of HPT varieties and provides a strategy for tailor-made crop improvement of both yield and lodging resistance in rice.

Bin Tu;Zhang Tao;Shiguang Wang;Lei Zhou;Ling Zheng;Chun Zhang;Xinzi Li;Xiaoyu Zhang;Junjie Yin;Xiaobo Zhu;Hua Yuan;Ting Li;Weilan Chen;Peng Qin;Bingtian Ma;Yuping Wang;Shigui Li

State Key Laboratory of Crop Gene Exploration and Utilization in Southwest China,Chengdu 611130,China;Rice Research Institute,Sichuan Agricultural University,Chengdu 611130,China;Guangdong Key Laboratory of New Technology in Rice Breeding,Rice Research Institute,Guangdong Academy of Agricultural Sciences,Guangzhou 510640,China;College of Agriculture and Horticulture,Chengdu Agricultural College,Chengdu 611130,China;Agriculture and Rural Affairs Bureau of Cuiping District,Yibin 644000,China

植物学报（英文版）

[1]Bin Tu;Zhang Tao;Shiguang Wang;Lei Zhou;Ling Zheng;Chun Zhang;Xinzi Li;Xiaoyu Zhang;Junjie Yin;Xiaobo Zhu;Hua Yuan;Ting Li;Weilan Chen;Peng Qin;Bingtian Ma;Yuping Wang;Shigui Li-.Loss of Gn1a/OsCKX2 confers heavy-panicle rice with excellent lodging resistance)[J].植物学报（英文版）,2022(01):23-38

Gn1a,OsCKX2,GRAIN,NUMBER,CYTOKININ,OXlDASE,Gn1A,gn1a,R498,gn1aR498,pyr,amiding,CULM,SCM2,SCM3

Loss,confers,heavy,rice,excellent,lodging,resistance,Significant,achievements,have,been,made,breeding,programs,type,HPT,Oryza,sativa,Southwest,China,varieties,now,exhibit,allowing,them,overcome,greater,pressures,caused,by,panicles,However,genetic,mechanism,this,remains,elusive,Here,isolated,major,quantitative,trait,locus,Panicle,Neck,Diameter,PND1,identified,causal,null,from,line,improved,through,increasing,culm,promoting,crown,development,function,led,cytokinin,accumulation,tip,accelerated,adventitious,roots,Gene,between,two,gain,alleles,STRONG,further,Moreover,had,minimal,influence,overall,quality,Our,research,thus,highlights,distinct,components,provides,strategy,tailor,crop,improvement,both,yield

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