Endogenous Polyamines and Ethylene Biosynthesis in Relation to Germination of Osmoprimed Brassica napus Seeds under Salt Stress.

Katarzyna Lechowska,Stanley Lutts,Muriel Quinet,Szymon Kubala,Małgorzata Garnczarska,Łukasz Wojtyla

doi:10.3390/ijms23010349

Abstract

Currently, seed priming is reported as an efficient and low-cost approach to increase crop yield, which could not only promote seed germination and improve plant growth state but also increase abiotic stress tolerance. Salinity represents one of the most significant abiotic stresses that alters multiple processes in plants. The accumulation of polyamines (PAs) in response to salt stress is one of the most remarkable plant metabolic responses. This paper examined the effect of osmopriming on endogenous polyamine metabolism at the germination and early seedling development of Brassica napus in relation to salinity tolerance. Free, conjugated and bound polyamines were analyzed, and changes in their accumulation were discussed with literature data. The most remarkable differences between the corresponding osmoprimed and unprimed seeds were visible in the free (spermine) and conjugated (putrescine, spermidine) fractions. The arginine decarboxylase pathway seems to be responsible for the accumulation of PAs in primed seeds. The obvious impact of seed priming on tyramine accumulation was also demonstrated. Moreover, the level of ethylene increased considerably in seedlings issued from primed seeds exposed to salt stress. It can be concluded that the polyamines are involved in creating the beneficial effect of osmopriming on germination and early growth of Brassica napus seedlings under saline conditions through moderate changes in their biosynthesis and accumulation.

Highlights

In the experimental layout used in this paper, the primed and unprimed seeds germinating on water or NaCl were collected at the same stage during germination
The primed dried seeds (Pd ), i.e., seeds soaked in priming agent (PEG) and dried to initial moisture content, and unprimed dry seeds (UPd )
Our results showed an elevation of the endogenous Put in primed seeds and in unprimed seeds germinated under salt stress

Summary

Introduction

Soil salinity is an increasingly severe problem worldwide, posing a severe threat to food security due to its negative impact on agricultural productivity and sustainability. The area under soil salinity is gradually spreading on all continents. According to data provided by the Food and Agriculture Organization via the Global Map of Salt-affected. Soils (GSASmap) tool, more than 3% of global topsoils and more than 6% of global subsoils are affected by salinity or sodicity [1]. Soil salinity affects more than 100 countries, and salt-affected soils occupy over 20% of the global irrigated area, increasing the range each day [2,3]. 2% of terrestrial plant species are salt tolerant (halophyte). The degree of salt tolerance varies among plant species and even cultivars [5]

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