Browsing by Author "Ljung, Karin"

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    A mechanistic framework for auxin dependent Arabidopsis root hair elongation to low external phosphate
    (Nature Publishing Group, 2018) Bhosale, Rahul; Giri, Jitender; Pandey, Bipin K.; Giehl, Ricardo F.H.; Hartmann, Anja; Traini, Richard; Truskina, Jekaterina; Leftley, Nicola; Hanlon, Meredith; Swarup, Kamal; Rashed, Afaf; Voß, Ute; Alonso, Jose; Stepanova, Anna; Yun, Jeonga; Ljung, Karin; Brown, Kathleen M.; Lynch, Jonathan P.; Dolan, Liam; Vernoux, Teva; Bishopp, Anthony; Wells, Darren; Wirén, Nicolaus von; Bennett, Malcolm J.; Swarup, Ranjan
    Phosphate (P) is an essential macronutrient for plant growth. Roots employ adaptive mechanisms to forage for P in soil. Root hair elongation is particularly important since P is immobile. Here we report that auxin plays a critical role promoting root hair growth in Arabidopsis in response to low external P. Mutants disrupting auxin synthesis (taa1) and transport (aux1) attenuate the low P root hair response. Conversely, targeting AUX1 expression in lateral root cap and epidermal cells rescues this low P response in aux1. Hence auxin transport from the root apex to differentiation zone promotes auxin-dependent hair response to low P. Low external P results in induction of root hair expressed auxin-inducible transcription factors ARF19, RSL2, and RSL4. Mutants lacking these genes disrupt the low P root hair response. We conclude auxin synthesis, transport and response pathway components play critical roles regulating this low P root adaptive response.
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    Rice auxin influx carrier OsAUX1 facilitates root hair elongation in response to low external phosphate
    (Nature Publishing Group, 2018) Giri, Jitender; Bhosale, Rahul; Huang, Guoqiang; Pandey, Bipin K.; Parker, Helen; Zappala, Susan; Yang, Jing; Dievart, Anne; Bureau, Charlotte; Ljung, Karin; Price, Adam; Rose, Terry; Larrieu, Antoine; Mairhofer, Stefan; Sturrock, Craig J.; White, Philip; Dupuy, Lionel; Hawkesford, Malcolm; Perin, Christophe; Liang, Wanqi; Peret, Benjamin; Hodgman, Charlie T.; Lynch, Jonathan; Wissuwa, Matthias; Zhang, Dabing; Pridmore, Tony; Mooney, Sacha J.; Guiderdoni, Emmanuel; Swarup, Ranjan; Bennett, Malcolm J.
    Root traits such as root angle and hair length influence resource acquisition particularly for immobile nutrients like phosphorus (P). Here, we attempted to modify root angle in rice by disrupting the OsAUX1 auxin influx transporter gene in an effort to improve rice P acquisition efficiency. We show by X-ray microCT imaging that root angle is altered in the osaux1 mutant, causing preferential foraging in the top soil where P normally accumulates, yet surprisingly, P acquisition efficiency does not improve. Through closer investigation, we reveal that OsAUX1 also promotes root hair elongation in response to P limitation. Reporter studies reveal that auxin response increases in the root hair zone in low P environments. We demonstrate that OsAUX1 functions to mobilize auxin from the root apex to the differentiation zone where this signal promotes hair elongation when roots encounter low external P. We conclude that auxin and OsAUX1 play key roles in promoting root foraging for P in rice.