Nitrogen Use Efficiency: Transport Solution in Rice Variations

Nitrogen use efficiency: Transport solution in rice variations

Bin Hu¹, Wei Wang¹, Shujun Ou¹, Jiuyou Tang¹, Hua Li¹, Ronghui Che¹, Zhihua Zhang¹, Xuyang Chai², Hongru Wang¹, Yiqin Wang¹, Chengzhen Liang¹, Linchuan Liu¹, Zhongze Piao⁴, Qiyun Deng⁴, Kun Deng¹, Chi Xu¹, Yan Liang¹, Lianhe Zhang¹, Legong Li², and Chengcai Chu^1*

¹State Key Laboratory of Plant Genomics, National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China;²College of Life Science, Capital Normal University, Beijing 100037, China; ³Crop Breeding and Cultivation Research Institute, Shanghai Academy of Agricultural Sciences, Shanghai 201106, China; ⁴China National Hybrid Rice Research and Development Center, Changsha 410125, China;

*Corresponding author: ccchu@genetics.ac.cn

Asian cultivated rice (Oryza sativa L.) consists of two main subspecies, indica and japonica. Indica has much higher nitrate absorption activity over japonica, but its molecular mechanism remains elusive. Here we show that variation in a nitrate transporter gene, NRT1.1B/OsNPF6.5, may largely contribute to this nitrate use divergence. Phylogenetic analysis revealed NRT1.1B diverges between indica and japonica, and the NRT1.1B-indica variation not only enhances nitrate uptake and root-to-shoot transport, also up-regulates expression of nitrate responsive genes. The signature of NRT1.1B-indica subjected to artificial selection unveiled the possible origin of nitrate use divergence during rice domestication. Notably, field tests with either near-isogenic or transgenic lines confirmed that japonica variety carrying NRT1.1B-indica allele had a significant improvement of grain yield and nitrogen use efficiency (NUE). Our results demonstrate that variation in NRT1.1B largely explains nitrate use divergence between indica and japonica, and that NRT1.1B-indica has great potential for improving NUE of japonica.

Key words: Rice; NRT1.1B; nitrate; nitrate transporter; nitrogen use efficiency