Wheat seeds priming with spermine or 1,3 – diamine propane was effective in supporting early seedlings growth by the adjustment of polyamine metabolism after Cd exposure

NM GOMEZ MANSUR; HERNANDIZ A; CF MARCHETTI; N DE DIEGO; SPICHAL L; GALLEGO SM; BENAVIDES MP

Mendoza

Congreso; LVIII SAIB; 2022

SAIB

Anthropogenic contamination affects crop production. Among the environmental pollutants, cadmium increment in the soil is affecting agricultural areas. Within the areas with increased risk are those for intending wheat (Triticum aestivum L.), one of the most important cereals in the world. Post-storage seed reinvigoration is one of the beneficial strategies proposed to improve early plant growth. On-farm seed priming is one of the many invigoration techniques increasingly used. It involves soaking the seeds in water or inorganic/organic compounds solution before sowing. Here, we used spermine (Spm) or 1,3 diamine propane (DAP) for seed priming to boost seedling growth under normal or Cd-stressed conditions. The study is focused on root and shoot polyamine (PA) homeostasis of two wheat varieties, Saeta (S) and Turandot (T). Seeds were placed in glass flasks containing 30 mL of distilled water or 25 µM Spm or DAP, 30 seeds per flask. After incubation for 8 h in darkness, at 120 rpm and 24 ± 2 °C, seeds were germinated on filter paper moistened with distilled water, in trays protected from desiccation for 24 h. Germinated seeds were transferred to trays containing Florcom SV® substrate previously moistened to field capacity with water or 100 μM CdCl2. Plants were cultivated in a controlled climate room; substrate humidity was maintained by watering with water or Cd solution.On day 7, root and shoot length were measured, and extracts for metabolite determination and PA-metabolism gene expression analysis were prepared. Cadaverine, putrescine, spermidine, spermine, agmatine, homospermidine (HomoSpd), and norspermidine (NorSpd) total and free-form contents were determined. Bioinformatic analysis was performed to find out genes associated with PA metabolism in the wheat genome. Primers were designed for diamine oxidase (DAO), polyamine oxidase (PAO), S-adenosylmethionine decarboxylase (SAMDC) and ornithine decarboxylase (ODC) genes. Seed priming reverted Cd-induced root growth inhibition. Root and leaf PA homeostasis was differently affected by Cd, as well as by seed priming. The metal increased gene expression of DAO and PAO and decreased that of SAMDC. The increase in H2O2 due to PA catabolism could be accounting for Cd-induced cell redox imbalance. Priming did not reverse the effects of Cd on gene expression but modified ODC and SAMDC transcript accumulation. This could suggest that priming regulates PAs homeostasis by controlling the entry of ornithine into the PA biosynthesis pathway and further biosynthesis of Spd and Spm. Results showed that seed priming was effective in sustaining early root growth during Cd exposure by regulating the interconversion between PA and their free/conjugated forms. Interestingly, this is the first report of NorSpd and HomoSpd presence in wheat.