AUTHOR=Liu Meiya , Xu Jiameng , Lou Heqiang , Fan Wei , Yang Jianli , Zheng Shaojian 

TITLE=Characterization of VuMATE1 Expression in Response to Iron Nutrition and Aluminum Stress Reveals Adaptation of Rice Bean (Vigna umbellata) to Acid Soils through Cis Regulation

JOURNAL=Frontiers in Plant Science

VOLUME=7

YEAR=2016

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2016.00511

DOI=10.3389/fpls.2016.00511

ISSN=1664-462X

ABSTRACT=<p>Rice bean (<italic>Vigna umbellata</italic>) <italic>VuMATE1</italic> appears to be constitutively expressed at vascular system but root apex, and Al stress extends its expression to root apex. Whether <italic>VuMATE1</italic> participates in both Al tolerance and Fe nutrition, and how <italic>VuMATE1</italic> expression is regulated is of great interest. In this study, the role of <italic>VuMATE1</italic> in Fe nutrition was characterized through <italic>in planta</italic> complementation assays. The transcriptional regulation of <italic>VuMATE1</italic> was investigated through promoter analysis and promoter-GUS reporter assays. The results showed that the expression of <italic>VuMATE1</italic> was regulated by Al stress but not Fe status. Complementation of <italic>frd3-1</italic> with <italic>VuMATE1</italic> under <italic>VuMATE1</italic> promoter could not restore phenotype, but restored with 35SCaMV promoter. Immunostaining of VuMATE1 revealed abnormal localization of VuMATE1 in vasculature. <italic>In planta</italic> GUS reporter assay identified Al-responsive <italic>cis</italic>-acting elements resided between -1228 and -574 bp. Promoter analysis revealed several <italic>cis</italic>-acting elements, but transcription is not simply regulated by one of these elements. We demonstrated that <italic>cis</italic> regulation of <italic>VuMATE1</italic> expression is involved in Al tolerance mechanism, while not involved in Fe nutrition. These results reveal the evolution of <italic>VuMATE1</italic> expression for better adaptation of rice bean to acid soils where Al stress imposed but Fe deficiency pressure released.</p>