Previous study showed that high concentration of Lanthanum (La), an important rare earth element, significantly inhibits primary root (PR) growth whereas it markedly induces lateral root development, and thereby regulates root system architecture. However, the physiological and molecular mechanisms underlying La-mediated root system architecture remain largely unclear.

Prof. XU Jin and his team of Xishuangbanna Tropical Botanical Garden (XTBG) investigated the involvement of auxin carriers in La-modulated auxin distribution in primary root (PR) tips.

They found that La inhibits auxin distribution in the primary root tips by repressing PINFORMED (PIN)-mediated auxin transport in PR tips.

First, La treatment inhibited IAA-, NAA-, and 2,4-D-induced DR5-GUS activity in the roots, suggesting that disturbing auxin transport by La changes auxin accumulation in PR tips.

Second, supplementation with the auxin transport inhibitor NPA did not further increase the La-mediated inhibitory effects on PR growth, suggesting a role of auxin transport in La-mediated PR growth inhibition.

Third, an investigation of the abundances of auxin carriers using transgenic lines expressing AUX1-YFP and PIN1/2/4/7-GFP showed that La repressed the abundances of all these auxin carriers in PR tips, and the pin1 and pin4-3 mutants were less sensitive to La-mediated PR growth inhibition, thus confirming that La-repressed auxin transport is involved in the PR growth inhibition response to La.

They also found that, although La markedly reduced auxin accumulation and the abundances of auxin carriers in PR tips, the auxin accumulation and the abundances of auxin carriers in LR are unaffected.

The results indicated that La treatment inhibits PIN-mediated auxin transport and subsequently impairs auxin distribution and PR growth via reducing auxin carrier abundances.

The study entitled “Lanthanum Inhibits Primary Root Growth by Repressing Auxin Carrier Abundances in Arabidopsis” has been published in Frontiers in Plant Science.

Contact

XU Jin, Ph.D Principal Investigator
Key Laboratory of Tropical Plant Resources and Sustainable Use, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun 666303, Yunnan, China
E-mail:  xujin@xtbg.ac.cn
Tel: +86 871 65140420