The nucleic acid form of iPR is catalyzed by CYP735A1 or CYP735A2 of the cytochrome oxidase P450 family to produce the nucleic acid form of tZR, which is finally converted to active CK by cytokinin phosphate ribose hydrolase (LOG). A total of eight members of the IPT gene family have been identified in rice. A total of nine members of the IPT gene family have been identified in Arabidopsis, of which AtIPT2 and AtIPT9 encode tRNA-isopentenyltransferases (tRNA synthesis pathway).

The first step in CK synthesis relies on adenosine phosphate-isopentenyltransferase (IPT) to catalyze the conversion of adenosine-5-phosphate (including AMP, ATP and ADP) and dimethylallyl-polyphosphate (DMAPP) or hydroxymethylbutenyl diphosphate (HMBDP) to the nucleic acid form of isopentenyl adenosine (N6-(Δ2-isopentenyl) adenine (iP) riboside, iPR). The other is the de novo synthesis pathway, which refers mainly to the cytokinin synthesis pathway that relies on two key rate-limiting enzymes ( Figure S1). However, this pathway is inefficient and does not meet the large amount of cytokinin required by plants. There are two main forms of trans-zeatin synthesis in plants, one is the tRNA pathway, which involves the synthesis of highly active trans-zeatin catalyzed by cis-trans isomerases using cis-zeatin released from the breakdown of tRNA as a substrate. Trans-zeatin, isolated from immature maize seeds in 1963, was the first cytokinin (t-zeatin) to be discovered and purified. In higher plants, cytokinin is mainly found in the form of zeatin, which includes both cis- and trans-zeatin, and trans-zeatin is the main active component of naturally occurring cytokinin.

In the last decade, the molecular regulation of cytokinin synthesis and signal transduction has been continuously elucidated in parallel with advances in biotechnology. Since cytokinin and auxin were identified as the two most important phytohormones that play a regulatory role in plant tissue culture, cytokinin research has gradually intensified. Overall, we systematically identified and analyzed key gene families of the cytokinin pathway in Moso bamboo and obtained key factors for auxin and cytokinin crosstalk, laying the foundation for the study of hormone regulation in Moso bamboo.Ĭytokinin (CK) plays an important role in physiological and biochemical responses such as cell division and expansion, induction of organ differentiation, delayed senescence, stress response and plant morphogenesis. Auxin and cytokinin signaling crosstalk to regulate Moso bamboo growth. The auxin signaling factor PheARF52 was identified by yeast one-hybrid assay as regulating the PheRR3 gene through a P-box element in the PheRR3 promoter region. Analysis of co-expression patterns at the developmental stages of Moso bamboo shoots revealed the existence of a phytohormone co-expression pattern centered on cytokinin signaling genes. Analysis of transcriptome data revealed a tissue-specific expression pattern of Moso bamboo cytokinin family genes, with auxin and gibberellin response patterns. The Moso bamboo cytokinin pathway was evolutionarily conservative and mainly underwent purifying selection, and that gene family expansion was mainly due to whole-gene duplication events. Phylogenetic analysis revealed that the cytokinin pathway was closely related to rice, and evolutionary pattern analysis found that most of the genes have syntenic relationship with rice-related genes. These included 15 IPT family genes, 19 LOG family genes, 22 HK family genes, 11 HP family genes and 62 RR family genes. In this study, a total of 129 candidate sequences were identified by bioinformatic methods. Cytokinin is widely involved in the regulation of plant growth, but its pathway-related genes have not been reported in Moso bamboo.

Moso bamboo zone