Hormonal Regulation and Crosstalk of Auxin/Cytokinin Signaling Pathways in Potatoes In Vitro and in Relation to Vegetation or Tuberization Stages

Abstract

Auxins and cytokinins create versatile regulatory network controlling virtually all aspects of plant growth and development. These hormonal systems act in close contact, synergistically or antagonistically, determining plant phenotype, resistance and productivity. However, the current knowledge about molecular interactions of these systems is still scarce. Our study with potato plants aimed at deciphering potential interactions between auxin and cytokinin signaling pathways at the level of respective gene expression. Potato plants grown on sterile medium with 1.5% (vegetation) or 5% (tuberization) sucrose were treated for 1 h with auxin or cytokinin. Effects of these two hormones on expression profiles of genes belonging to main signaling pathways of auxin and cytokinin were quantified by RT-qPCR. As a result, several signaling genes were found to respond to auxin and/or cytokinin by up- or down-regulation. The observed effects were largely organ-specific and depended on sucrose content. Auxin strongly reduced cytokinin perception apparatus while reciprocal cytokinin effect was ambiguous and sucrose-dependent. In many cases, functional clustering of genes of the same family was observed. Promoters in some clusters are enriched with canonic hormone-response cis-elements supporting their direct sensitivity to hormones. Collectively, our data shed new light on the crosstalk between auxin- and cytokinin signaling pathways.

Auxin/Cytokinin Antagonistic Control of the Shoot/Root Growth Ratio and Its Relevance for Adaptation to Drought and Nutrient Deficiency Stresses

“…In contrast, severe cytokinin resistance caused by the simultaneous loss of function of the ARR1, ARR10, and ARR12 cytokinin response activators did not impact auxin signaling intensity [35], indicating that this antagonistic auxin/cytokinin interaction at the signaling level is also unidirectional. Two recent reports have provided further evidence for this conclusion [147,156]. These studies show that transgenic increase in endogenous auxin and auxin treatments of potato plants, decrease cytokinin content and strongly repress cytokinin signaling genes, whereas cytokinin treatment leads to an ambiguous and sucrose-dependent effect on auxin signaling [147,156].…”

“…Two recent reports have provided further evidence for this conclusion [147,156]. These studies show that transgenic increase in endogenous auxin and auxin treatments of potato plants, decrease cytokinin content and strongly repress cytokinin signaling genes, whereas cytokinin treatment leads to an ambiguous and sucrose-dependent effect on auxin signaling [147,156].…”

A high trans-zeatin nucleoside concentration in corms may promote the multileaf growth of Amorphophallus muelleri

“…This may allow cytokinins in corms to directly promote bud outgrowth. In addition, COI1B , which encodes the F-BOX protein in the IAA signaling pathway, was highly expressed during the second leaf sprouting period, and it could regulate the biosynthesis of cytokinins by repressing the expression of IPTs ( Schaller et al., 2015 ; Kolachevskaya et al., 2021 ). This may also be an important reason why the expression of IPTs did not increase significantly during the second leaf sprouting period.…”

Cytokinin Perception in Ancient Plants beyond Angiospermae

“…Thus, in the course of evolution, the CK signaling system gained great importance and multifunctionality, which caused its perfecting and rapid development towards the virtual monopolization of MSP; direct, not through tRNA, CK synthesis, as well as expansion of the receptor specificity with their subsequent specialization to certain CKs in flowering plants. At the same time, the CK system acquired greater reliability, stability and plasticity, as evidences, in particular, its resistance against blocking (knockouting) of one or another of its essential elements [ 31 , 72 ] as well as fine-tune coordination of the CK system with other hormonal systems, primarily auxin [ 73 , 74 ] and ethylene [ 75 ] ones, to ensure the optimal development of the plant organism.…”