Paraquat-tolerant rice created via multi-target gene editing by China’s Zhejiang University research team

A few days ago, Liu Jianxiang’s research team from the Institute of Plant Biology, College of Life Sciences, Zhejiang University of China published an a research paper online titled ″Disruption of the three polyamine uptake transporter genes in rice by CRISPR/Cas9 gene editing confers tolerance to herbicide paraquat.″ 

The research uses multi-target gene editing, simultaneously mutating three OsPUT (polyamine uptake transporter) genes in rice. The research has significantly enabled the tolerance of rice to paraquat, which paves the way for future export of technology and widespread applications in rice fields.

By comparing the Arabidopsis paraquat transporter AtRMV1, the research team identified the presence of the three homologous genes OsPUT1/2/3 in rice. Via the multi-target CRISPR-Cas9 system, the three genes were edited simultaneously to have obtained paraquat-tolerant rice substances. Whether being seedlings or one-month-old rice plants, after being treated with paraquat, mutants show a significant tolerance regarding plant height and fresh weight (Figure 1). 

Despite the disruption of the OsPUT genes, mutants and wild-type plants show no significant phenotypic difference when planted in the field without treatment by herbicides, where agronomic traits such as plant height, growth period and yield are not affected (Figure 1).

Given that the target of paraquat is the chloroplast photosynthetic system, the paper’s writer further observed the chloroplast structure after being treated. The results reveal that treatment with to paraquat caused the leaves of wild-type plants to be more prone to loss of green and the chloroplast structure to be disordered, whilst mutants could maintain a complete chloroplast structure even at high concentrations (5 μM). 

Meanwhile, paraquat is enriched in both leaves and roots of the wild-type plants while the content in mutants is reduced significantly. Therefore, paraquat-tolerant rice germplasm materials created by gene editing have shown an apparent tolerance, which has a great potential for applications. Moreover, the research provides a good reference for the increase of tolerance of other crops.

Figure 1   Creation of paraquat-tolerant rice

A: Phenotypic analysis of rice plants of one-month-old wild-type (WT) and two triple mutants (OsPUTs-KO-1 and OsPUTs-KO-6) treated with 200 μM paraquat. 

B: Analysis of basic agronomic traits of wild-type and mutants under normal growth

Paper Link: https://doi.org/10.1007/s42994-022-00075-4