Natural variation for Fe-efficiency is associated with upregulation of Strategy I mechanisms and enhanced citrate and ethylene synthesis in Pisum sativum L.
Iron (Fe)-deficiency is a common abiotic stress in Pisum sativum L. grown in many parts of the world. The aim of the study was to investigate variation in tolerance to Fe deficiency in two pea genotypes, Santi (Fe-efficient) and Parafield (Fe-inefficient). Fe deficiency caused greater declines in chlorophyll score, leaf Fe concentration and root–shoot development in Parafield compared to Santi, suggesting greater Fe-efficiency in Santi. Fe chelate reductase activity and ethylene production were increased in the roots of Santi and to a lesser extent in Parafield under Fe deficiency, while proton extrusion was only occurred in Santi. Moreover, expression of the Fe chelate reductase gene, FRO1, and Fe transporter, RIT1 were upregulated in Fe-deficient roots of Santi. Expression of HA1 (proton extrusion) was also significantly higher in Santi when compared to Parafield grown in Fe-deficient conditions. Furthermore, the application of the ethylene biosynthesis inhibitor, 1-aminoisobutyric acid reduced the Fe chelate reductase activity, supporting a direct role for ethylene in its induction. A significant increase in root citrate was only observed in Santi under Fe deficiency indicating a role for citrate in the Fe-efficiency mechanism. Taken together, our physiological and molecular data indicate that genotypic variation in tolerance to Fe deficiency in Santi and Parafield plants is a result of variation in a number of Strategy I mechanisms and also suggest a direct role for ethylene in Fe reductase activity. The pea cultivar, Santi provides a new source of Fe-efficiency that can be exploited to breed more Fe-efficient peas.
KeywordsField peas Fe deficiency tolerance Proton extrusion Fe chelate reductase Ethylene
- Christin H, Petty P, Ouertani K, Burgado S, Lawrence C, Kassem MA (2009) Influence of iron, potassium, magnesium, and nitrogen deficiencies on the growth and development of sorghum (Sorghum bicolor L.) and sunflower (Helianthus annuus L.) seedlings. J Biotech Res 1:64–71Google Scholar
- Gharsalli M, Zribi K, Hajji M (2001) Physiological responses of pea to iron deficiency induced by bicarbonate. Plant Nutr 92(8):606–607Google Scholar
- Ramirez-Rodriguez V, Nieto-Jacobo MF, Lopez-Bucio J, Herrera-Estrella L (2001) Effect of citrate overproduction on iron nutrition in plants. Plant Nutr 92(1):44–45Google Scholar
- Reuter DJ, Robinson BJ (1997) Plant analysis: an interpretation manual. CSIRO Publishing, Collingwood, pp 272–273Google Scholar
- Waters BM, Lucena C, Romera FJ, Jester GG, Wynn AN, Rojas CL, Alcantara E, Perez-Vicente R (2007) Ethylene involvement in the regulation of the H+-ATPase CsHA1 gene and of the new isolated ferric reductase CsFRO1 and iron transporter CsIRT1 genes in cucumber plants. Plant Physiol Biochem 45:293–301PubMedCrossRefGoogle Scholar
- Yakop UM (2008) Genetic investigations of iron deficiency in field peas (Pisum sativum L.). PhD thesis, School of Agriculture and Wine, The University of AdelaideGoogle Scholar