Arabidopsis phosphatidylinositol 4‐phosphate 5‐kinase genes PIP5K7, PIP5K8, and PIP5K9 are redundantly involved in root growth adaptation to osmotic stress

Abstract

Phosphatidylinositol 4-phosphate 5-kinase (PIP5K) produces phosphatidylinositol (4,5)-bisphosphate (PtdIns (4,5)P 2 ), a signaling phospholipid critical for various cellular processes in eukaryotes. The Arabidopsis thaliana genome encodes 11 PIP5K genes. Of these, three type B PIP5K genes, PIP5K7, PIP5K8, and PIP5K9, constitute a subgroup highly conserved in land plants, suggesting that they retain a critical function shared by land plants. In this study, we comprehensively investigated the biological functions of the PIP5K7-9 subgroup genes. Reporter gene analyses revealed their preferential expression in meristematic and vascular tissues. Their YFP-fusion proteins localized primarily to the plasma membrane in root meristem epidermal cells. We selected a mutant line that was considered to be null for each gene. Under normal growth conditions, neither single mutants nor multiple mutants of any combination exhibited noticeable phenotypic changes. However, stress conditions with mannitol or NaCl suppressed main root growth and reduced proximal root meristem size to a greater extent in the pip5k7pip5k8pip5k9 triple mutant than in the wild type. In root meristem epidermal cells of the triple mutant, where plasma membrane localization of the PtdIns(4,5) P 2 marker P24Y is impaired to a large extent, brefeldin A body formation is retarded compared with the wild type under hyperosmotic stress. These results indicate that PIP5K7, PIP5K8, and PIP5K9 are not required under normal growth conditions, but are redundantly involved in root growth adaptation to hyperosmotic conditions, possibly through the PtdIns(4,5)P 2 function promoting plasma membrane recycling in root meristem cells.

Integrated Analysis of Single-Molecule Real-Time Sequencing and Next-Generation Sequencing Eveals Insights into Drought Tolerance Mechanism of Lolium multiflorum

“…LmPIP5K9 produced two different transcripts, i.e., CDS1 (i2_LQ_DE_c113853/f1p10/2988) and CDS2 (i3_LQ_DE_c41394/f1p1/3368), through alternative splicing of a retained intron (RI), each of which may perform different functions in L. multiflorum ( Figure 8 A). Read counts of the two transcripts indicated that the expression levels of CDS1 and CDS2 were low in both leaf and root samples under normal growth conditions, which was consistent with a recent study [ 34 ]. This finding implies that LmPIP5K9 is not required under normal growth conditions.…”

“…This finding implies that LmPIP5K9 is not required under normal growth conditions. Additionally, CDS1 is rapidly upregulated, about four-fold, after induction by drought stress, which is also corroborated by other studies [ 34 , 35 ]. However, the expression of CDS2, which itself is low under normal growth conditions, is further down-regulated and almost not expressed at all under drought stress.…”

Salinity tolerance mechanisms of an Arctic Pelagophyte using comparative transcriptomic and gene expression analysis

“…Overexpression of kinases is a frequent reaction to perturbation within the cell, such as disease or stress 43 . Some PKs associated with osmoregulation and salt stress, such as phosphatidylinositol-4-phosphate 5-kinase (PIP5k) are involved in root growth adaptation to hyperosmotic conditions in Arabidopsis 44 . In our case, PIP5k was overexpressed at S.8, along with numerous other PKs suggesting a more general stress response (Figs.…”

Genome-wide identification of PIP5K in wheat and its relationship with anther male sterility induced by high temperature

“…Moreover, the recent study of AtPIP5K7–9 subgroup by Kuroda et al shows that these genes have little effect on plant growth and development under favorable growth conditions, but they are found to be involved in the adaptation of root growth to osmotic stress. Besides, these genes expressed in other tissues may also participate in the adaptation to stress conditions [ 17 , 18 ]. AtPIP5K10 and AtPIP5K11 genes are specifically expressed in pollen grains and can also play a role in pollen tube growth through actin cytoskeleton recombination [ 14 ].…”