Meta-Topolin (m-Topolin)

Meta-Topolin (m-Topolin) is a potent aromatic cytokinin from poplar leaves with wide applications in micropropagation^[1]. As an important class of plant growth regulators, cytokinins influence almost every stage of plant development^[2].Meta-Topolin promotes cell division, enhances shoot proliferation, and delays leaf senescence, making it particularly valuable in applications such as plant tissue culture, crop genetic improvement, and research on cytokinin signaling pathways^[3,4].

In vitro, treating Ferdor rootstock shoots with 2.1μM Meta-Topolin for three subculture cycles significantly improved shoot growth and quality (including shoot fresh weight, number of internodes, shoot length, and leaf area)^[5]. When cotyledonary node explants of Pterocarpus marsupium were treated with a combination of 7.5μM Meta-Topolin and 1.0μM α-naphthalene acetic acid (NAA) for 12 weeks, 85% of the explants responded, producing an average of 17.44 ± 0.25 shoots per explant with an average shoot length of 5.72 ± 0.18cm. This regeneration efficiency was notably superior to that achieved using 6-benzyladenine (BA) in combination with NAA^[6]. Furthermore, treatment of wheat leaves with Meta-Topolin (0.25, 0.5, and 1.0mM) for 10 days resulted in a concentration-dependent increase in fresh weight and a respective increase of 14%, 23%, and 41% in chlorophyll a content, along with a similar protective effect on chlorophyll b, effectively delaying leaf senescence^[7].

References:
[1] STRNAD M, HANUŠ J, VANĚK T, et al. Meta-topolin, a highly active aromatic cytokinin from poplar leaves (Populus×canadensis Moench., cv. Robusta)[J]. Phytochemistry, 1997, 45(2): 213-218.
[2] UNAL B T. The use of meta-topolin in cell and tissue cultures for increasing production of secondary metabolites[M]//Meta-topolin: a growth regulator for plant biotechnology and agriculture. Singapore: Springer Singapore, 2021: 253-263.
[3] GANTAIT S, MITRA M. Role of meta-topolin on in vitro shoot regeneration: an insight[M]//Meta-topolin: a growth regulator for plant biotechnology and agriculture. Singapore: Springer Singapore, 2021: 143-168.
[4] MANOKARI M, MEHTA S R, PRIYADHARSHINI S, et al. Meta-Topolin mediated improved micropropagation, foliar micro-morphological traits, biochemical profiling, and assessment of genetic fidelity in Santalum album L.[J]. Industrial Crops and Products, 2021, 171: 113931.
[5] GENTILE A, JÀQUEZ GUTIÉRREZ M, MARTINEZ J, et al. Effect of meta-Topolin on micropropagation and adventitious shoot regeneration in Prunus rootstocks[J]. Plant Cell, Tissue and Organ Culture, 2014, 118(3): 373-381.
[6] AHMAD A, ANIS M. Meta-topolin improves in vitro morphogenesis, rhizogenesis and biochemical analysis in Pterocarpus marsupium Roxb.: a potential drug-yielding tree[J]. Journal of Plant Growth Regulation, 2019, 38(3): 1007-1016.
[7] PALAVAN-ÜNSAL N, ÇAĞ S, ÇETIN E, et al. Retardation of senescence by meta-topolin in wheat leaves[J]. Journal of Cellular and Molecular Biology, 2002, 1: 101-108.

Meta-Topolin (m-Topolin) 是一种从杨树叶中分离出来的，可用于微繁殖的高活性芳香细胞分裂素^[1]。细胞分裂素是一类重要的植物生长调节剂，几乎可以影响植物生长的各个阶段^[2]。Meta-Topolin具有诱导植物细胞分裂、促进芽增殖和延缓叶片衰老等有益特性，通常用于植物组织培养、作物遗传改良及细胞分裂素信号通路等研究^[3,4]。

在体外，Meta-Topolin（2.1μM）处理砧木Ferdor的离体芽3个继代周期，显著提升了芽的生长和质量（鲜重、节间数、芽长），增大了叶片面积^[5]。7.5μM Meta-Topolin与1.0μM α-naphthalene acetic acid （NAA）组合处理囊状紫檀子叶节外植体12周，在85%的外植体中诱导出平均每外植体17.44 ± 0.25个芽，平均芽长5.72 ± 0.18cm，增殖效果显著优于6-benzyladenine （BA）与NAA的组合^[6]。Meta-Topolin（0.25, 0.5, 1.0mM）处理小麦叶片10天，不仅叶片的鲜重存在浓度依赖性的增加，叶绿素a的含量也分别提升14，23和41%，并表现出对叶绿素b相同的保护趋势，有效延缓了叶片的衰老^[7]。