Morphological and genetic changes induced by excess Zn in roots of Medicago truncatula A17 and a Zn accumulating mutant.

Ricky W. Lewis, Guiliang Tang, David H. McNear

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


Nutrient fluxes associated with legume-rhizobia symbioses are poorly understood and little is known regarding the influence of abiotic stresses on development and maintenance of N-fixing nodules and root system architecture (RSA). We examined effects of Zn on nodule development and structure, root architecture, and expression of nodulation-related miRNAs in Medicago truncatula and the mutant, raz (requires additional Zn). Excess Zn increased root and shoot associated Zn in both genotypes, however, raz plants had lower root associated Zn than WT plants. Roots of raz plants exposed to excess Zn had less volume, surface area, and total length compared to WT plants. Raz plants had lower lateral root number than WT plants. Excess Zn was found to increase root diameter in both genotypes. The Mn Translocation Factor (TfMn) increased in response to Zn in both genotypes; this was more pronounced in raz plants. TfZn was higher in raz plants and reduced in both genotypes in response to Zn. Nodulation was not influenced by Zn treatment or plant genotype. MicroRNA166 was upregulated under excess Zn in WT plants. Neither the raz mutation nor Zn treatment affected nodulation, however, raz plants had altered RSA compared with WT and responded differently to Zn, implying the mutation potentially modulates RSA responses to Zn but doesn't play a direct role in nodulation. MicroRNA166 was significantly induced in WT plants by excess Zn, warranting further investigation into the potential role it plays in controlling RSA.

Original languageEnglish
Article number657
Pages (from-to)657
Number of pages1
JournalUnknown Journal
StatePublished - 2012

Bibliographical note

Funding Information:
We appreciate seed gifts from Michael Grusak, Hongyan Zhu, and Troy Bass. Sinorhizobium meliloti stock was provided by Janine Sherrier, for which we are very grateful. We thank Olga Tsyusko, Mohammad Babar Ali, Xiaoyun Jia, Ligang Ren and B. Usha for advice on qRT-PCR and general RNA/miRNA methodology, and Jason Unrine for metals analysis via ICP-MS. We also thank Maria Labreveux and Xia Yu for assistance with statistical analysis, and Joseph V. Kupper and Rebecca Sims for assistance with general lab work. This work was funded by the University of Kentucky Department of Plant and Soil Science.

ASJC Scopus subject areas

  • General Biochemistry, Genetics and Molecular Biology


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