Dataset Information

MYB10 and MYB72 are required for growth under iron-limiting conditions.

ABSTRACT: Iron is essential for photosynthesis and is often a limiting nutrient for plant productivity. Plants respond to conditions of iron deficiency by increasing transcript abundance of key genes involved in iron homeostasis, but only a few regulators of these genes have been identified. Using genome-wide expression analysis, we searched for transcription factors that are induced within 24 hours after transferring plants to iron-deficient growth conditions. Out of nearly 100 transcription factors shown to be up-regulated, we identified MYB10 and MYB72 as the most highly induced transcription factors. Here, we show that MYB10 and MYB72 are functionally redundant and are required for plant survival in alkaline soil where iron availability is greatly restricted. myb10myb72 double mutants fail to induce transcript accumulation of the nicotianamine synthase gene NAS4. Both myb10myb72 mutants and nas4-1 mutants have reduced iron concentrations, chlorophyll levels, and shoot mass under iron-limiting conditions, indicating that these genes are essential for proper plant growth. The double myb10myb72 mutant also showed nickel and zinc sensitivity, similar to the nas4 mutant. Ectopic expression of NAS4 rescues myb10myb72 plants, suggesting that loss of NAS4 is the primary defect in these plants and emphasizes the importance of nicotianamine, an iron chelator, in iron homeostasis. Overall, our results provide evidence that MYB10 and MYB72 act early in the iron-deficiency regulatory cascade to drive gene expression of NAS4 and are essential for plant survival under iron deficiency.

SUBMITTER: Palmer CM

PROVIDER: S-EPMC3836873 | biostudies-literature | 2013 Nov

REPOSITORIES: biostudies-literature

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MYB10 and MYB72 are required for growth under iron-limiting conditions.

Palmer Christine M CM Hindt Maria N MN Schmidt Holger H Clemens Stephan S Guerinot Mary Lou ML

PLoS genetics 20131121 11

Iron is essential for photosynthesis and is often a limiting nutrient for plant productivity. Plants respond to conditions of iron deficiency by increasing transcript abundance of key genes involved in iron homeostasis, but only a few regulators of these genes have been identified. Using genome-wide expression analysis, we searched for transcription factors that are induced within 24 hours after transferring plants to iron-deficient growth conditions. Out of nearly 100 transcription factors show ...[more]

PMID: 24278034

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Project description:Zinc is an essential micronutrient required for proper structure and function of many proteins. Bacteria regularly encounter zinc depletion and have evolved diverse mechanisms to continue growth when zinc is limited, including the expression of zinc-independent paralogs of zinc-binding proteins. Mycobacteria have a conserved operon encoding four zinc-independent alternative ribosomal proteins (AltRPs) that are expressed when zinc is depleted. It is unknown if mycobacterial AltRPs replace their primary paralogs in the ribosome and maintain protein synthesis under zinc-limited conditions, and if such replacements contribute to their physiology. This study shows that AltRPs from Mycobacterium smegmatis are essential for growth when zinc ion is scarce. Specifically, the deletion mutant of this operon (ΔaltRP) is unable to grow in media containing a high-affinity zinc chelator, while growth of the wild type strain is unaffected under the same conditions. However, when zinc is gradually depleted during growth in zinc-limited medium, the ΔaltRP mutant maintains the same growth rate as seen for the wild type strain. In contrast to M. smegmatis grown with sufficient zinc supplementation that forms shorter cells when transitioning from logarithmic to stationary phase, M. smegmatis deficient for zinc elongates after the expression of AltRPs in late logarithmic phase. These zinc-depleted bacteria also exhibit a remarkable morphology characterized by a condensed chromosome, increased number of polyphosphate granules, and distinct appearance of lipid bodies and the cell wall compared to the zinc-replete cells. However, the ΔaltRP cells fail to elongate and transition into the zinc-limited morphotype, resembling the wild type zinc-replete bacteria instead. Therefore, the altRP operon in M. smegmatis has a vital role in continuation of growth when zinc is scarce and in triggering specific morphogenesis during the adaptation to zinc limitation, suggesting that AltRPs can functionally replace their zinc-dependent paralogs, but also contribute to mycobacterial physiology in a unique way.

Dataset Information

MYB10 and MYB72 are required for growth under iron-limiting conditions.

Publications

MYB10 and MYB72 are required for growth under iron-limiting conditions.

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