Phosphorus restriction induces early changes in the proteome of soybean leaves, and affects nitric oxide metabolism.

ANDREA GALATRO; MARCELA SIMONTACCHI; ANALÍA LIMA; FACUNDO RAMOS ARTUSO; CARLOS BATTHYÁNY DIGHIERO

Nice

Congreso; 7th Plant Nitric Oxide International Meeting.; 2018

Symbiose and Redox State of the Cell - Institut Sophia Agrobiotech, Sophia Antipolis, France

Phosphorus (P) is a macronutrient with structural and regulatory functions, essential for energy transfer. Under limited P availability, plant cells respond to internal signals, adjusting their metabolic pathways, and reorganizing priorities in an attempt to maintain P homeostasis. This work was conducted with the aim to explore the initial changes following P deprivation, when neither photosynthesis nor growth were strongly affected. Soybean plants (Glycine max, Williams 82) were grown hydroponically and the first unifoliate leaves were analyzed after 24 h of P-deprivation. During the first week plants were maintained under control conditions (+P, nutrient solution containing 500 µM H2PO4-), afterward a group of plants was transferred to a medium restricted in phosphate (-P, without H2PO4- in the nutrient solution). After 24 h of P-deprivation, total P concentration decreased significantly in leaves from P-starved plants as compared to the control group (51 3 µmol P g-1 FW and 401 µmol P g-1 FW, respectively). Shotgun Proteomic Analysis revealed that a total of 202 proteins were differentially expressed, and 232 proteins were increased in leaves from plants after 24 h of P-deprivation as compared to control. The proteins affected (not present in control plants or increased in P-restricted) belong mainly to the catalytic group, according to Phanter gene ontology classification system. Early events in leaves also involved higher levels of the bioactive molecule nitric oxide (NO) as well as reactive oxygen species (ROS), detected after 24 h of P-restriction employing fluorescent probes combined with confocal laser microscopy. Furthermore, the presence of nitrated proteins was also analyzed. This post-translational protein modification, related with the presence of NO, was observed in both control and P-restricted plants. The results indicate that a short P-deprivation period induce several changes in the proteome of leaves affecting metabolic processes that could be related to the early implementation of acclimation responses, when levels of P and photosynthesis in leaves were not yet drastically affected.