A NAD(P) reductase like protein is the salicylic acid receptor in the appendix of theSauromatum guttatuminflorescence

Abstract

The mode of action of the thermogenic inducers (salicylic acid, aspirin, and 2,6-dihydroxybenzoic acid) in the appendix of the Sauromatum guttatum inflorescence is poorly understood. Using ESI-MS and light scattering analysis, we have demonstrated that NAD(P) reductase like protein (RL) is the salicylic acid receptor in the Sauromatum appendix. RL was self-assembled in water into a large unit with a hydrodynamic diameter of 800 nm. In the presence of 1 pM salicylic acid, RL exhibited discontinuous and reversible volume phase transitions. The volume phase changed from 800 to 300 nm diameter and vice versa. RL stayed at each volume phase for ~4–5 min with a fast relaxation time between the 2 phases. ESI-MS analysis of RL extracted from appendices treated with salicylic acid, aspirin, and 2,6-DHBA at a micromolar range demonstrated that these compounds are capable of inducing graded conformational changes that are concentration-dependent. A strong correlation between RL conformations and heat-production induced by salicylic acid was also observed. These preliminary findings reveal structural and conformational roles for RL by which plants regulate their temperature and synchronize their time keeping mechanisms.

Thermoregulation in the appendix of the Sauromatum guttatum (Schott) inflorescence

“…In Arabidopsis leaves, a non-thermogenic plant, it was present in state A. Furthermore, addition of SA at pM concentration to the purified protein solution induced a reversible volume phase transition every 4–5 min for at least 30 min (Skubatz et al [ 2013 ]). These changes in the protein conformation may result in variation in the response to the inducers.…”

“…Treatment of pre D-Day (3 to 1 d prior to heat-production) appendix sections with SA at concentrations higher than 1 μM induced significant increases in temperature (Skubatz et al [2013]). Salicylic acid effects are not confined only to the spadix of arum lilies.…”

“…Salicylic acid, ASA, and 2,6-DHBA activate the temperature rise as well as odor-production in the Sauromatum appendix (Raskin et al [ 1989 ]). Treatment of pre D-Day (3 to 1 d prior to heat-production) appendix sections with SA at concentrations higher than 1 μM induced significant increases in temperature (Skubatz et al [ 2013 ]). Salicylic acid effects are not confined only to the spadix of arum lilies.…”