Open Access
ARTICLE
The Physiological Mechanisms Underlying N2-Fixing Common Bean (Phaseolus vulgaris L.) Tolerance to Iron Deficiency
Abdelmajid Krouma1,2,*
1
Faculty of Sciences and Techniques, University of Kairouan, Sidi Bouzid, 9100, Tunisia
2
Laboratory of Ecosystems and Biodiversity in Arid Land of Tunisia, Faculty of Sciences, University of Sfax, Sfax, Tunisia
* Corresponding Author: Abdelmajid Krouma. Email: -kairouan.tn
(This article belongs to this Special Issue: Abiotic and Biotic Stress Tolerance in Crop)
Phyton-International Journal of Experimental Botany 2023, 92(7), 2133-2150. https://doi.org/10.32604/phyton.2023.029048
Received 29 January 2023; Accepted 03 March 2023; Issue published 29 May 2023
Abstract
Iron is an essential element for plants as well as all living organisms, functioning in various physiological and
biochemical processes such as photosynthesis, respiration, DNA synthesis, and N
2 fixation. In the soil, Fe bioavailability is extremely low, especially under aerobic conditions and at high pH ranges. In contrast, plants with
nodules on their roots that fix atmospheric nitrogen need much more iron. To highlight the physiological traits
underlying the tolerance of N
2-fixing common bean to iron deficiency, two genotypes were hydroponically cultivated in a greenhouse: Coco nain (CN) and Coco blanc (CB). Plants were inoculated with an efficient strain of
Rhizobium tropici, CIAT899, and received a nutrient solution added with 0 µM Fe (severe Fe deficiency, SFeD),
5 µM Fe (moderate Fe deficiency, MFeD) or 45 µM Fe (control, C). Several physiological parameters related to
photosynthesis and symbiotic nitrogen fixation were then analyzed. Iron deficiency significantly reduced whole
plant and nodule growth, chlorophyll biosynthesis, photosynthesis, leghemoglobin (LgHb), nitrogenase (N
2ase)
activity, nitrogen, and Fe nutrition, with some genotypic differences. As compared to CB, CN maintained better
Fe allocation to shoots and nodules, allowing it to preserve the integrity of its photosynthetic and symbiotic apparatus, thus maintaining the key functional traits of the plant metabolism (chlorophyll biosynthesis and photosynthesis in shoots, leghemoglobin accumulation, and nitrogenase activity in root nodules). Plant growth
depends on photosynthesis, which needs to be supplied with sufficient iron and nitrogen. Fe deficiency stress
index (FeD-SI) and Fe use efficiency (FeUE) are two physiological traits of tolerance that discriminated the
studied genotypes.
Keywords
Cite This Article
Krouma, A. (2023). The Physiological Mechanisms Underlying N
2-Fixing Common Bean (
Phaseolus vulgaris L.) Tolerance to Iron Deficiency.
Phyton-International Journal of Experimental Botany, 92(7), 2133–2150.