Hormopriming to Mitigate Abiotic Stress Effects: A Case Study of N9-Substituted Cytokinin Derivatives With a Fluorinated Carbohydrate Moiety

Abstract

Drought and salinity reduce seed germination, seedling emergence, and early seedling establishment, affect plant metabolism, and hence, reduce crop yield. Development of technologies that can increase plant tolerance of these challenging growth conditions is a major current interest among plant scientists and breeders. Seed priming has become established as one of the practical approaches that can alleviate the negative impact of many environmental stresses and improve the germination and overall performance of crops. Hormopriming using different plant growth regulators has been widely demonstrated as effective, but information about using cytokinins (CKs) as priming agents is limited to only a few studies using kinetin or 6-benzylaminopurine (BAP). Moreover, the mode of action of these compounds in improving seed and plant fitness through priming has not yet been studied. For many years, BAP has been one of the CKs most commonly applied exogenously to plants to delay senescence and reduce the impact of stress. However, rapid endogenous N9-glucosylation of BAP can result in negative effects. This can be suppressed by hydroxylation of the benzyl ring or by appropriate N9 purine substitution. Replacement of the 2′ or 3′ hydroxyl groups of a nucleoside with a fluorine atom has shown promising results in drug research and biochemistry as a means of enhancing biological activity and increasing chemical or metabolic stability. Here, we show that the application of this chemical modification in four new N9-substituted CK derivatives with a fluorinated carbohydrate moiety improved the antisenescence properties of CKs. Besides, detailed phenotypical analysis of the growth and development of Arabidopsis plants primed with the new CK analogs over a broad concentration range and under various environmental conditions revealed that they improve growth regulation and antistress activity. Seed priming with, for example, 6-(3-hydroxybenzylamino)-2′-deoxy-2′-fluoro-9-(β)-D-arabinofuranosylpurine promoted plant growth under control conditions and alleviated the negative effects of the salt and osmotic stress. The mode of action of this hormopriming and its effect on plant metabolism were further analyzed through quantification of the endogenous levels of phytohormones such as CKs, auxins and abscisic acid, and the results are discussed.

Seed Priming With Protein Hydrolysates Improves Arabidopsis Growth and Stress Tolerance to Abiotic Stresses

“…However, instead of using single compounds such as polyamines, we tested the effects of 11 complex products based on protein hydrolysates from different natural origins, applied in three different concentrations (0.001, 0.01, and 0.1 μl ml –1 ) as seed priming agents. Priming induces preliminary germination ( Jisha et al, 2012 ; Paparella et al, 2015 ), enhances synchronized germination, promotes plant growth ( Bryksová et al, 2020 ) and can elicit resilience to stressors ( Conrath, 2011 ; Paparella et al, 2015 ). Priming can improve seed performance, ensure higher uniformity among the seeds, result in faster and better.…”

Priming with Small Molecule-Based Biostimulants to Improve Abiotic Stress Tolerance in Arabidopsis thaliana

“…Moreover, priming causes changes in the growth pattern and alterations in the plant metabolism and, hence, in the plant stress tolerance and resistance [ 33 , 34 ]. Plant phenotyping platforms are valuable tools for characterizing plant biostimulants or other priming agents, so they can quickly scan a multitude of variables and/or parameters, allowing a high-throughput pipeline [ 35 , 36 ]. Previous studies performed in the XYZ system (Olophen phenotyping platform) have already been proven as an accurate method to evaluate the efficiency of the seed priming for our in vitro assays based on A. thaliana rosette growth [ 29 , 31 ].…”

Presence and future of plant phenotyping approaches in biostimulant research and development

“…The advantage of this methodology is that it can simultaneously analyze 572 plates (counting 27 456 seedlings). This means that this ultra-HTS approach allows the simultaneous testing of many compounds from different natural sources at a wide range of concentrations in Arabidopsis seedlings grown under different growth conditions, including osmotic stress, salt stress, or nutritional stress ( De Diego et al , 2017 ; Bryksová et al , 2020 ).…”