Enhanced putrescine levels improve nitrogen use efficiency and vegetative growth in Arabidopsis plants under nitrogen limitation

Abstract

To achieve sustainable agriculture, it is crucial to reduce nitrogenated fertilizer inputs and enhance nitrogen use efficiency (NUE).Polyamines (PAs) are known intermediates in plant nitrogen flux; however, their significance under N restriction has been scarcelyaddressed. We hypothesize that elevated putrescine levels enhance plant performance under nitrogen limitation by improvingnitrogen metabolism, maintaining photosynthetic efficiency, and strengthening antioxidant defenses. This study compares theperformance of a transgenic Arabidopsis (Arabidopsis thaliana) line that constitutively overexpresses arginine decarboxylase 2 gene(ADC2), involved in Put production, with that of wild type (WT) under nitrogen-sufficient (N+) or nitrogen-deficient (N−) conditions.Under N−, the ADC2-overexpressing line showed greater rosette growth and more secondary roots compared to WT. This line alsoexhibited enhanced nitrate transporter 1.1 gene (NRT1.1) expression and greater nitrate reductase activity; these findings coincidedwith higher rosette nitrate content. The ADC2-overexpressing line showed increased NUE and, unlike the WT, variation in mostphotosynthetic parameters did not occur due to N restriction. Moreover, the Put overproducer demonstrated higher guaiacolperoxidase and catalase activities and lower thiobarbituric acid reactive substances levels. Our findings indicate that enhancedPutrescine content in Arabidopsis may contribute to a more effective overall distribution and utilization of N, preventing oxidativedamage during the vegetative period and allowing plants to better adapt to this nutritional imbalance. These results suggest thatgenetic manipulation of PA metabolism represents a promising strategy for improving NUE in crops, a crucial advancement forenvironmentally sustainable and economically viable agriculture in nitrogen-limited environments.