Auxin modulates the enhanced development of root hairs in Arabidopsis thaliana (L.) Heynh. under elevated CO2

• Published in: Plant, cell and environment cell and environment, 2011-08, Vol.34 (8), p.1304-1317
• Main Authors: NIU, YAOFANG, JIN, CHONGWEI, JIN, GULEI, ZHOU, QINGYAN, LIN, XIANYONG, TANG, CAIXIAN, ZHANG, YONGSONG
• Format: Article
• Language: English
• Subjects: Arabidopsis thaliana; auxin signalling; nutrient acquisition; root morphology
• ISSN: 0140-7791; 1365-3040
• DOI: 10.1111/j.1365-3040.2011.02330.x

ABSTRACT Root hairs may play a critical role in nutrient acquisition of plants grown under elevated CO2. This study investigated how elevated CO2 enhanced the development of root hairs in Arabidopsis thaliana (L.) Heynh. The plants under elevated CO2 (800 µL L−1) had denser and longer root hairs, and more H‐positioned cells in root epidermis than those under ambient CO2 (350 µL L−1). The elevated CO2 increased auxin production in roots. Under elevated CO2, application of either 1‐naphthoxyacetic acid (1‐NOA) or N‐1‐naphthylphthalamic acid (NPA) blocked the enhanced development of root hairs. The opposite was true when the plants under ambient CO2 were treated with 1‐naphthylacetic acid (NAA), an auxin analogue. Furthermore, the elevated CO2 did not enhance the development of root hairs in auxin‐response mutants, axr1‐3, and auxin‐transporter mutants, axr4‐1, aux1‐7 and pin1‐1. Both elevated CO2 and NAA application increased expressions of caprice, triptychon and rho‐related protein from plants 2, and decreased expressions of werewolf, GLABRA2, GLABRA3 and the transparent testa glabra 1, genes related to root‐hair development, while 1‐NOA and NPA application had an opposite effect. Our study suggests that elevated CO2 enhanced the development of root hairs in Arabidopsis via the well‐characterized auxin signalling and transport that modulate the initiation of root hairs and the expression of its specific genes. This study demonstrated a profound effect of elevated CO2 on development of root hairs in Arabidopsis through well‐characterized auxin signalling pathways. It opens up the opportunity of understanding on how the cellular networks of positional signals initiate the cell‐specific expression of a number of transcription factors conferring the tolerance to environment stresses in Arabidopsis. The changes in root morphology provide the plant an efficient strategy to alleviate the limitation of nutrients under elevated CO2, an important part of climate change. The results have an important implication as to how the positive effects of elevated CO2 can be maximized through plant adaptive strategies to improve nutrient acquisition.