Abstract
The plasma membrane-associated Ca(2+)-binding protein-2 of Arabidopsis thaliana is involved in the growth of root hair tips. Several transgenic lines that overexpress the 23 residue N-terminal domain of this protein under the control of the root hair-specific EXPANSIN A7 promoter lack root hairs completely. The role of root hairs under normal and stress conditions was examined in one of these root hair-less lines (NR23). Compared with the wild type, NR23 showed a 47% reduction in water absorption, decreased drought tolerance, and a lower ability to adapt to heat. Growth of NR23 was suppressed in media deficient in phosphorus, iron, calcium, zinc, copper, or potassium. Also, the content of an individual mineral in NR23 grown in normal medium, or in medium lacking a specific mineral, was relatively low. In wild-type plants, the primary and lateral roots produce numerous root hairs that become elongated under phosphate-deficient conditions; NR23 did not produce root hairs. Although several isoforms of the plasma membrane phosphate transporters including PHT1;1-PHT1;6 were markedly induced after growth in phosphate-deficient medium, the levels induced in NR23 were less than half those observed in the wild type. In phosphate-deficient medium, the amounts of acid phosphatase, malate, and citrate secreted from NR23 roots were 38, 9, and 16% of the levels secreted from wild-type roots. The present results suggest that root hairs play significant roles in the absorption of water and several minerals, secretion of acid phosphatase(s) and organic acids, and in penetration of the primary roots into gels.
Highlights
Root hairs, which are specialized epidermal cells with a large surface area exposed to soil, exhibit tip growth similar to pollen tubes
Root hairs have been suggested to play an important role in the absorption of nutrients and water, and in root anchoring at the elongation stage
The root hair-less Arabidopsis line, no root hair line that expresses N23 (NR23), which was produced from the overexpression of the N-terminal region of plasma membrane-associated Ca2+-binding protein-2 (PCaP2) (N23) in a root hair cell-specific manner (Kato et al, 2013), was investigated
Summary
Root hairs, which are specialized epidermal cells with a large surface area exposed to soil, exhibit tip growth similar to pollen tubes. Molecular biological analyses of root hairs have identified several root hair-specific genes, such as RHD6 (At1G66470; transcription factor), RHD2 (At5G51060; signalling protein), and EXPA7 (At1g12560; expansin) (Cho, 2013). At present, these transcription factors and signal transducers involved in root hair differentiation and development have been identified (Jones et al, 2002; Ishida et al, 2008; Datta et al, 2011; Yi et al, 2010). Mutant and transgenic lines with different root hair phenotypes provide a means for studying the physical and physiological contributions of root hairs to the plant life cycle
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.