TY  - EJOU
AU  - Krouma, Abdelmajid 

TI  - The Physiological Mechanisms Underlying N<sub>2</sub>-Fixing Common Bean (<i>Phaseolus vulgaris</i> L.) Tolerance to Iron Deficiency
T2  - Phyton-International Journal of Experimental Botany

PY  - 2023
VL  - 92
IS  - 7
SN  - 1851-5657

AB  - 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<sub>2</sub> 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<sub>2</sub>-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
<i>Rhizobium tropici</i>, 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<sub>2</sub>ase)
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.
KW  - Common bean; iron deficiency; Fe-deficiency stress index; Fe use efficiency; leghemoglobin; nitrogenase activity; photosynthesis

DO  - 10.32604/phyton.2023.029048