New cytokinin-like compounds as a tool to improve rooting and establishment of micropropagated plantlets
Inadequate or lack of rooting remains a major physiological challenge during plant micropropagation. Successful acclimatization of in vitro regenerants, which is a crucial stage in every micropropagation protocol, depends on the achievement of well-rooted plants. This is crucial for large-scale application of in vitro techniques/protocols. Given that the first objective of the micropropagation endeavor is the shoot proliferation, the wide utilization and popularity of cytokinins (CKs) remain inevitable. Thus, increasing research efforts have been geared toward enhancing the efficiency and reducing the negative effect of the commonly used CKs on rooting stage. Furthermore, the recent major advances in chromatographic and spectrometric techniques have helped in the search for new molecules/compounds because of the more accurate and precise quantification and understanding of CK metabolites and other associated phytohormones. In addition to meta-Topolin (mT and its derivatives), which has proved to be an alternative to the commonly used 6-benzylaminopurine (BAP), other CK analogous, such as 2-chloro-6-(3-methoxyphenyl)aminopurine (INCYDE) and the CK antagonist 6-(2-hydroxy-3-methylbenzylamino)purine (PI-55) have been developed. Based on recent experimental data, the potential (with regards to enhancing rooting and acclimatization) of these aforementioned compounds in micropropagation protocols are highlighted in this review. This is largely due to the less toxic or residual effects of these new compounds when compared to the traditionally used aromatic and isoprenoid CKs.
Aremu, A.O., Dole¿al, K. and Van Staden, J. 2017. New cytokinin-like compounds as a tool to improve rooting and establishment of micropropagated plantlets. Acta Hort. (ISHS) 1155:497-504
auxin, cytokinin oxidase, meta-topolin, plant acclimatization, physiological disorders, phytohormones