Pretreatment of wheat seeds with polyamines modulates seedling growth by regulating hormonal and redox balance

GOMEZ MANSUR NABILA MARIA; SPICHAL LUKAS; NOVAK ONDRA; RECALDE LAURA; CAVAR SANJA; GALLEGO SUSANA; DE DIEGO NURIA; PENCIK ALEX; BENAVIDES PATRICIA

Virtual

Congreso; LVI SAIB-XV SAMIGE Reunión Conjunta 2020. Edición on-line.; 2020

SAIB

Polyamines (PAs) are nitrogen compounds involved in plant growth and development. PAs also play an important role against biotic and abiotic stress, partially through the improvement of the cell redox status. It is known that pre-conditioning or priming seeds with chemicals compounds leads to a physiological state that improves seed germination and post-germinative growth. Herein, we present preliminary data related to the effect of treating wheat (Triticum aestivum L) seeds with PAs. Seeds (20/25) were soaked with 30 mL distilled water (C) or 25µM spermine (Spm), spermidine (Spd) or putrescine (Put) for 3h in an orbital shaker (24 ± 2 °C, darkness). After germinating on wet filter paper during 30 h (24±2°C, darkness), seedlings were transferred to pots containing vermiculite (3 seedlings per pot), and at least 8 pot per treatment were prepared for each experiment. Plants were grown in a growth chamber (photoperiod 14/10 h light/dark, 24±2 °C, 50% relative humidity) and irrigated with diluted (1/4) Hoagland´s nutrient solution. After 6 d, plants were harvested; the roots were washed with distilled water and separated from the aerial part. PAs significantly incremented root length (up to 12 % over the control), but only Put increased leaf length (10% over the control). Root and leaf biomass, determined as fresh weight (FW) and dry weight (DW) were unaffected by the PAs pretreatment. Free and conjugated Spm, Spd, Put, cadaverine, diaminopropane and hormones were measured by UHPLC, and contents were calculated by g-1 DW. Priming altered the pattern and free/conjugated ratio of all PAs both in roots and leaves. PAs pretreatment induced an adaptive hormonal homeostasis. Indol acetic acid (IAA) content increased by PAs in leaves, but only Put raised AIA content in roots. Total cytokinins increased by Spm in roots and by Put and Spd in leaves. The production of reactive oxygen (ROS) and nitrogen species (RNS) were assessed in roots using the fluorescence probes dihydroethidium and diaminofluorescein diacetate respectively. Fluorescence was visualizing using an EPI-fluorescent microscope equipped with a digital photo camera. Intensity fluorescence measurements for quantification were done using ImageJ software. ROS and RNS production increased in roots of seedlings primed with Spm. On the contrary, Spd decreased fluorescence of both probes. Put decreased ROS, but increased RNS. Superoxide dismutase -the enzyme that converts O2- to H2O2- activity was increased by Spm and Spd (15% and 20% over the C), but decreased 10% with Put. All PAs increase guaiacol peroxidase activity, one of the enzymes involved in H2O2 detoxification. Priming with PAs altered their metabolisms, and seedling´s hormonal and redox status, that leads to the promotion of root elongation. These data are indicating that PAs could be promising priming agents to better prepare plants to grow in normal and adverse environmental conditions.