Cadmium (Cd) is a nonnutrient metal that is potentially toxic even at low concentrations in plants. Abscisic acid (ABA) reduces accumulation of Cd in plants. However, how ABA signaling affects Cd uptake by modulating IRT1 expression remains largely unclear.
In a recent study published online in Plant Physiology, researchers from Xishuangbanna Tropical Botanical Garden (XTBG) reported that the basic region/leucine zipper TF ABSCISIC ACID141 INSENSITIVE5 (ABI5) is involved in Cd accumulation. As a central ABA signaling molecule, the ABI5 is involved in ABA-repressed Cd accumulation in plants by physically interacting with a previously uncharacterized R2R3-MYB transcription factor MYB49.
Overexpression of ABI5 reduces, whereas loss of function in the abi5 mutant increases, Cd accumulation in Arabidopsis, indicating the involvement of ABI5 in modulating Cd uptake.
To identify transcriptional regulators involved in ABI5-mediated Cd accumulation, the researchers searched for ABI5-interacting proteins and identified the Cd-induced R2R3-MYB TF MYB49.
The researchers also examined the function and the roles of an uncharacterized R2R3-MYB member, MYB49, in Arabidopsis, they found that Arabidopsis MYB49 regulates Cd accumulation by directly regulating bHLH38, bHLH101, HIPP22, and HIPP44 expression.
Considering that Cd toxicity induces endogenous ABA accumulation in plants, the researchers suggest that a feedback mechanism based on physical interactions between MYB49 and ABI5 controls Cd uptake and accumulation in plant cells.
“The results enabled us to understand the mechanisms underlying plant response to Cd stress through the actions of MYB49 and ABI5”, said Prof. XU Jin, principal investigator of the study.
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
Tel: +86 871 65140420