Division of cortical cells is regulated by auxin in Arabidopsis roots

Abstract

The root cortex transports water and nutrients absorbed by the root epidermis into the vasculature and stores substances such as starch, resins, and essential oils. The cortical cells are also deeply involved in determining epidermal cell fate. In Arabidopsis thaliana roots, the cortex is composed of a single cell layer generated by a single round of periclinal division of the cortex/endodermis initials. To further explore cortex development, we traced the development of the cortex by counting cortical cells. Unlike vascular cells, whose number increased during the development of root apical meristem (RAM), the number of cortical cells did not change, indicating that cortical cells do not divide during RAM development. However, auxin-induced cortical cell division, and this finding was confirmed by treatment with the auxin transport inhibitor N-1-naphthylphthalamic acid (NPA) and examining transgenic plants harboring CO2::ΔARF5, in which cortical expression of truncated AUXIN RESPONSE FACTOR5 (ΔARF5) induces auxin responses. NPA-induced cortical auxin accumulation and CO2::ΔARF5-mediated cortical auxin response induced anticlinal and periclinal cell divisions, thus increasing the number of cortical cells. These findings reveal a tight link between auxin and cortical cell division, suggesting that auxin is a key player in determining root cortical cell division.

TheArabidopsissplicing factor PORCUPINE/SmE1 orchestrates temperature-dependent root development via auxin homeostasis maintenance

“…Auxin has been shown to have a strong impact on the regulation of cell 20 shape and division through modulation of the cytoskeleton (Vaddepalli et al, 2021;García-González & van Gelderen, 2021). In line with these observations, a recent study has shown that activation of cortical auxin response induces anticlinal and periclinal cell divisions, as well as abnormal root hair patterning (Kim et al, 2022). While our pDR5::SAND auxin response marker showed no activation in the cortex of pcp-1, we observed that cortical cell morphology and root hair density was partially rescued in response to auxinole, while root hair density increased in response to IAA in Col-0 at 16°C.…”

Single-cell proteomics differentiates Arabidopsis root cell types

“…We also identified RBOHD enriched in endodermal cells where is known to activate ROS-dependent signaling to help CS formation 49,50 . Conversely, ARF5 is enriched in the cortex, expression of this gene in the cortex can drive cortical cell division 51 . At the same time, we found the cochaperone P23-1 enriched in cortex, where it has been reported to be crucial for auxin distribution and proper number of cortical cells 52,53 .…”

“…Additionally, NPY5/MEL1 is enriched in endodermal cells, where it has been reported to control PIN1 subcellular basal localization and root gravitropic response 48 . Conversely, ARF5 is enriched in the cortex, expression of this gene in the cortex can drive cortical cell division 49 . At the same time, we found TT7 enriched in cortex, where it has been reported to control anthocyanin-dependent auxin flux by altering the expression of PIN1 auxin transporter 50,51 .…”

Unveiling nutrient flow-mediated stress in plant roots using an on-chip phytofluidic device

“…The water and nutrients absorbed by the root epidermis are transported by the cortex, located between the root epidermis and the endodermis, into the vascular bundle by apoplastic and symplastic routes, and are involved in determining the fate of epidermal cells. 80 The cortex in plants is a relatively undifferentiated cell type called ground tissue. Although the cortex layers vary among species, they remain almost unchanged at a particular developmental stage for a specific species.…”