Genetic Control of Seed Phytate Accumulation and the Development of Low-Phytate Crops: A Review and Perspective

Abstract

Breeding low phytic acid (lpa) crops is a strategy that has potential to both improve the nutritional quality of food and feed and contribute to the sustainability of agriculture. Here, we review the lipid-independent and -dependent pathways of phytate synthesis and their regulatory mechanisms in plants. We compare the genetic variation of the phytate concentration and distribution in seeds between dicot and monocot species as well as the associated temporal and spatial expression patterns of the genes involved in phytate synthesis and transport. Quantitative trait loci or significant single nucleotide polymorphisms for the seed phytate concentration have been identified in different plant species by linkage and association mapping, and some genes have been cloned from lpa mutants. We summarize the effects of various lpa mutations on important agronomic traits in crop plants and propose SULTR3;3 and SULTR3;4 as optimal target genes for lpa crop breeding.

Rice ins(3)P synthase1 (RINO1) participates in embryonic development by regulating inositol‐associated changes in auxin synthesis and its distribution

“…This result was well consistent with several previous reports, which concluded that the Arabidopsis mutant lacking mips1 significantly reduced the levels of major PIs and exhibited much slower rates of endocytosis than the non-transgenic controls (Chen & Xiong, 2010;Wang et al, 2022). Hence, our present results confirmed the close association of aberrant embryogenesis with the sharply dropping levels of inositol and phosphatidylinositides in seed embryos.…”

“…Previous studies have demonstrated that silencing the expression of RINO1 caused a substantial decrease in seed InsP 6 content and a simultaneous increase in seed Pi content for the transgenic rice mutants (Raboy, 2009; Ali et al, 2013). Transgenic plants with reduced MIPS expression by antisense or RNA interference suppressions commonly exhibited inferior seed germination and/or aberrant embryo development (Kuwano et al, 2009; Zhou et al, 2018; Wang et al, 2022). Conversely, several other studies on wheat and rice revealed that the seed tissue targeted downregulation of MIPS expression resulted in a marked reduction in seed InsP 6 content without a significantly negative impact on seed germination and seedling growth (Guttieri et al, 2004; Ali et al, 2013).…”

“…Huang et al (2017) found that OsGCD1 was required for the formation of the dorsal‐ventral axis in rice embryos. However, the participation of genes related to the InsP 6 biosynthetic pathway in rice embryonic development has rarely been reported (Yi et al, 2016; Wang et al, 2022). In our present study, the differentiating scutellum (sc) and coleoptile (cp) of rino1‐cas1 −/− and rino1‐cas2 −/− were visually found in the ventral and apical regions of seed embryos at the coleoptilar stage (Figure 3A,4A).…”

“…Hence, our present results confirmed the close association of aberrant embryogenesis with the sharply dropping levels of inositol and phosphatidylinositides in seed embryos. Previous studies on Arabidopsis and other plant species, such as maize and soybean, had revealed that a sufficient PIs supply was important for auxin transport and localization to regulate embryo development (Luo et al, 2011; Wang et al, 2022). AtMIPS1 mutants had defects in vein formation and auxin response (Yi et al, 2016).…”

“…Furthermore, previous studies had not discriminated the difference between the causative factors stemming from the defects in the embryos and those from the lowering seed vitality of normal embryos for the inferior seed germination of LPA mutants (Wang et al, 2022).…”