Find in Library

Inositol 1,3,4-trisphosphate 5/6-kinase (ITPK) is encoded by six genes in rice (<i>OsITPK1-6</i>). A previous study had shown that nucleotide substitutions of <i>OsITPK6</i> could significantly lower the phytic acid content in rice grains. In the present study, the possibility of establishing a genome editing-based method for breeding low-phytic acid cultivars in rice was explored, in conjunction with the functional determination of OsITPK6. Four <i>OsITPK6</i> mutant lines were generated by targeted mutagenesis of the gene&#8217;s first exon using the CRISPR/Cas9 method, one (<i>ositpk6_1</i>) with a 6-bp in-frame deletion, and other three with frameshift mutations (<i>ositpk6_2</i>, _<i>3</i>, and _<i>4</i>). The frameshift mutations severely impaired plant growth and reproduction, while the effect of <i>ositpk6_1</i> was relatively limited. The mutant lines <i>ositpk6_1</i> and _<i>2</i> had significantly lower levels (&#8722;10.1% and &#8722;32.1%) of phytic acid and higher levels (4.12- and 5.18-fold) of inorganic phosphorus compared with the wild-type (WT) line. The line <i>ositpk6_1</i> also showed less tolerance to osmotic stresses. Our research demonstrates that mutations of <i>OsITPK6</i>, while effectively reducing phytic acid biosynthesis in rice grain, could significantly impair plant growth and reproduction.