Phosphorus deprivation in soybean plants induces early acclimation responses and affects endogenous nitric oxide levels

LUQUET, MELISA; GALATRO, ANDREA; GERGOFF GROZEFF, GUSTAVO; BUET, AGUSTINA

Congreso; XXXIII Argentinian meeting of plant physiology; 2021

Nitric Oxide (NO) is known to be involved in plant responses to essential mineral nutrient deficiencies. In this work we evaluated initial changes following phosphorus (P) deprivation in soybean plants focusing on NO levels and the triggering of some acclimation responses. Soybean plants (Glycine max cv. Williams 82) were cultivated in modified Hoagland´s solution containing 500 µM H3PO4 (control, +P) or without H3PO4 (-P), at 28 °C/22 °C day-night, 400 μmol m−2 s-1 of PAR, and 16-h photoperiod. Plants were grown under +P condition for 7 d, then a group of plants were moved to -P treatments, and growth and physiological parameters were evaluated up to 96 h of treatment. P concentration decreased 64 % in -P roots and unifoliate leaves, and 40 % in trifoliate leaves respect to control values at 96 h. However, neither growth nor photosynthesis was strongly affected. The decrease in P levels correlated with an increase in NO content in leaves, that was strongly inhibited by treatment with sodium tungstate (an inhibitor of nitrate reductase). Acid phosphatase activity tend to increase in leaves and roots of -P plants, being two-fold higher in roots after 96 h of -P treatment. The levels of organic acids were measured employing HPLC, and malic and citric acid production seem to be stimulated in -P roots. Overall, the correlation between NO levels and P concentration, and the activation of some acclimation responses might indicate the involvement of reactive nitrogen species in signaling pathways during the first hours of P deprivation.