Diverse Effect of Two Cytokinins, Kinetin and Benzyladenine, on Plant Development, Biotic Stress Tolerance, and Gene Expression

Abstract

The plant hormones cytokinins affect a various array of plant growth and development processes as well as responses to biotic and abiotic stresses. In this study, the opposite effect of two different cytokinins kinetin (N6-furfuryladenine) and benzyladenine (BA) on development and on the tolerance of Arabidopsis and tobacco plants to virus, bacteria, and fungi infection was reported. Treatments of Arabidopsis and tobacco seedlings with saturated solutions of BA inhibited plant progress, while treatments with saturated water solution of kinetin promoted plant development. Furthermore, BA pre-treatments strongly reduced the number of TMV (Tobacco mosaic virus) lesions on tobacco and the tissue damage caused by the incompatible Pseudomonas bacteria on Arabidopsis and tobacco leaves. Similarly, BA pre-treatment significantly reduced the necrotic disease symptoms of Botrytis cinerea infection. Kinetin pre-treatments had a much weaker or no protective effect on the damage caused by the above pathogens. Accordingly, Arabidopsis gene expression profiles after treatments also showed that the two cytokinins have different effects on several plant processes. The gene expression results supported the more robust effect of BA, which up and downregulated more than 2000 genes, while only 436 genes were influenced by kinetin treatment. It is noteworthy that BA and kinetin treatment changed gene expressions in the same direction only in a relatively few cases (73 upregulated and 70 downregulated genes), and even 28 genes were regulated into the opposite directions by BA and kinetin. Both treatments had a strong effect on auxin and gibberellin-related genes, but only BA had a significant effect on cytokinin-induced processes. While kinetin exclusively activated the flavonoid synthesis genes, BA affected more significantly protein synthesis, photosynthesis, and plant defence-related genes. In conclusion, BA solution had sometimes the opposite and generally a much stronger effect than kinetin solution not only on the development and on biotic stress tolerance of tobacco and Arabidopsis plants but also on the gene expressions. The stronger protective effect of BA to necrotic stresses is probably due to its stronger senescence inhibitory effect on plant tissues, as supported by the stronger chlorophyll retardation of the BA-treated leaves.

Identification, evolution, and expression of GDSL-type Esterase/Lipase (GELP) gene family in three cotton species: a bioinformatic analysis

“…Co-silencing of AtCUS1 and AtCUS2 resulted in severe alteration of floral organ development [ 92 , 44 ]. AtCUS3 is a Guard-cell-enriched GDSL lipase (GGL26) to influence the opening, density, and morphology of stoma possibly under regulation of GA signal [ 6 , 11 , 113 ]. AtCUS4 is controlled by drought and Brassinosteroids [ 9 , 37 , 120 ].…”

Tolerance of plant virus disease: Its genetic, physiological, and epidemiological significance

“…Cytokinins affect many growth, development and physiological traits and have been shown to affect biotic and abiotic stress tolerance. In A. thaliana challenged with tobacco mosaic virus, the bacterium P. syringae , and the necrotrophic fungus Botrytis cinerea , effects were manifested differently depending on the cytokinin, whether kinetin or benzyladenine (BA) (Bózso & Barna, 2021). BA had a much stronger protective effect on necrotic stress due to senescence‐inhibition of BA‐treated leaves.…”

Evolving role of synthetic cytokinin 6-benzyl adenine for drought stress tolerance in soybean (Glycine max L. Merr.)

“…In contrast, foliar application of 6-BAP solutions at concentration ranging between 20 and 200 mgL −1 presented maximum plant establishment and net assimilation rates, together with higher yields in soybean plants subjected to induced drought stress. 6-BAP was reported to improve water use efficiency progressively with decreased irrigation and gradually increasing the amounts of the hormone (Bozso and Barna, 2021;El-Metwally et al, 2021;Amoanimaa-Dede et al, 2022;Gu et al, 2022). Therefore, more scientific evidence is required to strengthen exogenous application of 6-BAP and other synthetic and naturally occurring hormones in playing a pivotal role in the modulation of shoot and root development, especially in response to biotic and abiotic stress.…”