Phytic acid is the principal storage form of phosphorus in plant seeds and an essential signalling molecule in several regulatory processes of plant development. However, it is known as an anti-nutrient compound owing to its potent chelating property. Thus, reducing the phytic acid content in crops is desirable. Studies involving regulation of MIPS and IPK1 genes to generate low phytate rice have been reported earlier. However, the functional significance of OsITPK and the effect of its down-regulation on phytic acid content and the associated pleiotropic effects on rice have not yet been investigated. In this study, tissue specific RNA interference (RNAi)-mediated down-regulation of a major ITPK homolog (OsITP5/6K-1) resulted in 46.2% decrease in phytic acid content of T₂ transgenic seeds with a subsequent 3-fold enhancement in the inorganic phosphorus content. Silencing of OsITP5/6K-1 altered the transcript levels of essential phytic acid pathway genes, without significantly affecting the transcript levels of other OsITPK homologs. Furthermore, the mapping of elements through X-ray microfluorescence analysis revealed significant changes in the spatial distribution pattern and translocation of elements in low phytate seeds. Additionally, low phytate polished seeds exhibited 1.3-fold and 1.6-fold enhancement in iron and zinc content in the grain endosperm, respectively. Silencing of OsITP5/6K-1 also altered the amino acid and myo-inositol content of the transgenic seeds. Our results successfully established that RNAi-mediated silencing of OsITP5/6K-1 gene significantly reduced the phytate levels in seeds without hampering the germination potential of seeds and plant growth. The present study provided an insight into the mechanism of phytic acid biosynthesis pathway.

植酸是植物种子中磷的主要储存形式，并且是植物发育的几种调控过程中的重要信号分子。然而，由于其有效的螯合性能，它被称为抗营养化合物。因此，减少作物中植酸的含量是理想的。早期已经报道了涉及调节MIPS和IPK1基因以产生低植酸水稻的研究。然而，尚未研究OsITPK的功能意义及其下调对植酸含量的影响以及对水稻的相关多效性作用。在这项研究中，组织特异性RNA干扰（RNAi）介导的主要ITPK同源物（OsITP5 / 6K-1的下调）导致T ₂转基因种子的植酸含量降低46.2％，随后无机磷含量提高3倍。OsITP5 / 6K-1的沉默改变了必需植酸途径基因的转录水平，而没有显着影响其他OsITPK同源物的转录水平。此外，通过X射线微荧光分析对元素进行的定位揭示了低植酸盐种子中元素的空间分布格局和易位性发生了重大变化。此外，低植酸抛光种子在籽粒胚乳中的铁和锌含量分别提高了1.3倍和1.6倍。沉默OsITP5 / 6K - 1还改变了氨基酸和肌醇的转基因种子的肌醇含量。我们的结果成功地确定，RNAi介导的OsITP5 / 6K-1基因沉默可显着降低种子中的肌醇六磷酸水平，而不会影响种子的发芽潜力和植物生长。本研究提供了关于植酸生物合成途径的机制的见解。