A urea-type cytokinin, 2-Cl-PBU, stimulates adventitious bud formation of Eucalyptus urophylla by repressing transcription of rboh1 gene

Peer Review #2 of "Physiological parameters and differential expression analysis of N-phenyl-N′-[6-(2-chlorobenzothiazol)-yl] urea-induced callus of Eucalyptus urophylla × Eucalyptus grandis (v0.1)"

“…GO enrichment analysis showed that many of the up-regulated DEGs were enriched in the photosynthesis process, which is consistent with our observation of the development of green embryogenic callus indicative of vigorous photosynthesis. Furthermore, the enrichment of up-regulated DEGs significantly involved in oxidoreductase activity is consistent with changes in the enzyme activities related to oxidation-reduction reactions, including those of SOD, CAT, and POD, which Huang (2014) found to be associated with organogenesis. Accordingly, it can be assumed that certain concentrations of antioxidative enzymes contribute to organogenic callus formation.…”

“…In this regard, few studies have reported the successful regeneration of E. grandis × E. urophylla via callus propagation (Ouyang et al, 2012;Ouyang and Li, 2016). Synthetic phenylurea derivatives are potent plant growth regulators that exhibit cytokinin-like activity in various culture systems (Chung et al, 2007;Werner and Schmülling, 2009;Turker et al, 2009;Huang et al, 2014;Liu et al, 2019), among which N-phenyl-Nʹ-[6-(2chlorobenzothiazol)-yl] urea (PBU) was first synthesized and purified in our laboratory (Li and Luo, 2001). It has been demonstrated that PBU is more efficient than 6-benzyladenine (6-BA ) in Eucalyptus callus induction (Ouyang et al, 2012), and, moreover, PBU-induced callus shows a higher frequency of adventitious bud induction upon transfer to adventitious bud-inducing medium (Li et al, 2015).…”

Tissue Culture of Corymbia and Eucalyptus

“…However, SP medium [108,[110][111][112], WPM minerals [113], WPM [114], B5 medium [115][116][117], N7 medium [86,118], JADS medium [98], EDM [119], and MS medium with White vitamins [89] have also been used. Callus is often induced in darkness, although basal organogenesis on shoots can occur in eucalypt shoot cultures that are maintained under light [45,46,64,98,120].…”

“…Thidiazuron (TDZ) and 2-Cl-PBU (i.e., 1-phenyl-3-(1,2,3-thiadiazol-5-yl) urea and N-phenyl-N -[6-(2-chlorobenzothiazol)-yl] urea, respectively) are potent promotors of callus formation in eucalypts. Organogenesis can be induced using 0.89 µM BA with 0.91 µM TDZ, or 0.5 µM TDZ with 0.2 µM 2,4-D for E. globulus [127,128], 2 µM TDZ, or 0.23 µM TDZ with 0.05 µM NAA, or 3 µM TDZ with 0.1 µM NAA for E. grandis × E. urophylla [89,123,128], and 2.27 µM TDZ with 0.54 µM NAA, or 1.14 µM 2-Cl-PBU with 0.57 µM IAA for E. urophylla [89,111,112]. Picloram (i.e., 4-Amino-3,5,6-trichloro-2-pyridinecarboxylic acid) has been used alone at 20.7 µM for E. urophylla organogenesis [86] or at 0.04 µM in combination with 2.25 µM BA for E. gunnii Hook.f.…”

Physiological parameters and differential expression analysis of N-phenyl-N′-[6-(2-chlorobenzothiazol)-yl] urea-induced callus of Eucalyptus urophylla × Eucalyptus grandis

“…Synthetic phenylurea derivatives are potent plant growth regulators that exhibit cytokinin-like activity in various culture systems (Chung, Chen & Chang, 2007;Werner & Schmülling, 2009;Turker, Yucesan & Gurel, 2009;Huang et al, 2014;Liu et al, 2019), among which N-phenyl-N′-[6-(2-chlorobenzothiazol)-yl] urea (PBU) was first synthesized and purified in our laboratory (Li & Luo, 2001). It has been demonstrated that PBU is more efficient than 6-benzyladenine (6-BA) in Eucalyptus callus induction (Ouyang et al, 2012), and, moreover, PBU-induced callus shows a higher frequency of adventitious bud induction upon transfer to adventitious bud-inducing medium (Li, Ouyang & Gan, 2015).…”