Ectopic overexpression of Eleusine coracana CAX3 confers tolerance to metal and ion stress in yeast and Arabidopsis

Gautam Jamra; Soma Ghosh; Nidhi Singh; Manas Kumar Tripathy; Aparna Aggarwal; Reema Devi Rajan Singh; Ashish Kumar Srivastava; Anil Kumar; Girdhar K Pandey

doi:10.1016/j.plaphy.2024.108613

Ectopic overexpression of Eleusine coracana CAX3 confers tolerance to metal and ion stress in yeast and Arabidopsis

Plant Physiol Biochem. 2024 Apr 21:211:108613. doi: 10.1016/j.plaphy.2024.108613. Online ahead of print.

Authors

Gautam Jamra¹, Soma Ghosh², Nidhi Singh², Manas Kumar Tripathy², Aparna Aggarwal³, Reema Devi Rajan Singh⁴, Ashish Kumar Srivastava⁴, Anil Kumar⁵, Girdhar K Pandey⁶

Affiliations

¹ Dept. of Plant Molecular Biology, University of Delhi South Campus, New Delhi, 110021, India; Dept. of Molecular Biology and Genetic Engineering, GBPUAT, Pantnagar Uttarakhand, 263145, India.
² Dept. of Plant Molecular Biology, University of Delhi South Campus, New Delhi, 110021, India.
³ Dept. of Molecular Biology and Genetic Engineering, GBPUAT, Pantnagar Uttarakhand, 263145, India.
⁴ Nuclear Agriculture and Biotechnology Division, Bhabha Atomic Research Centre, Mumbai, 400085, India.
⁵ Dept. of Plant Molecular Biology, University of Delhi South Campus, New Delhi, 110021, India; Dept. of Molecular Biology and Genetic Engineering, GBPUAT, Pantnagar Uttarakhand, 263145, India; Director Education, Rani Lakshmi Bai Central Agriculture University, Jhansi, NH-75, Near Pahuj Dam, Gwalior Road, Jhansi, Uttar Pradesh, 284003, India. Electronic address: directoreducation.rlbcau@gmail.com.
⁶ Dept. of Plant Molecular Biology, University of Delhi South Campus, New Delhi, 110021, India. Electronic address: gkpandey@south.du.ac.in.

PMID: 38696868
DOI: 10.1016/j.plaphy.2024.108613

Abstract

Ionic and metal toxicity in plants is still a global problem for the environment, agricultural productivity and ultimately poses human health threats when these metal ions accumulate in edible organs of plants. Metal and ion transport from cytosol to the vacuole is considered an important component of metal and ion tolerance and a plant's potential utility in phytoremediation. Finger millet (Eleusine coracana) is an orphan crop but has prominent nutritional value in comparison to other cereals. Previous transcriptomic studies suggested that one of the calcium/proton exchanger (EcCAX3) is strongly upregulated during different developmental stages of spikes development in plant. This finding led us to speculate that high calcium accumulation in the grain might be because of CAX3 function. Moreover, phylogenetic analysis shows that EcCAX3 is more closely related to foxtail millet, sorghum and rice CAX3 protein. To decipher the functional role of EcCAX3, we have adopted complementation of yeast triple mutant K677 (Δpmc1Δvcx1Δcnb1), which has defective calcium transport machinery. Furthermore, metal tolerance assay shows that EcCAX3 expression conferred tolerance to different metal stresses in yeast. The gain-of-function study suggests that EcCAX3 overexpressing Arabidopsis plants shows better tolerance to higher concentration of different metal ions as compared to wild type Col-0 plants. EcCAX3-overexpression transgenic lines exhibits abundance of metal transporters and cation exchanger transporter transcripts under metal stress conditions. Furthermore, EcCAX3-overexpression lines have higher accumulation of macro- and micro-elements under different metal stress. Overall, this finding highlights the functional role of EcCAX3 in the regulation of metal and ion homeostasis and this could be potentially utilized to engineer metal fortification and generation of stress tolerant crops in near future.

Keywords: CAX3; Finger millet; Ions and metal homeostasis; Toxicity; Transporter; Yeast complementation.