β-Cyclodextrin-Hemin Complex-Induced Lateral Root Formation In Tomato: Involvement Of Nitric Oxide And Heme Oxygenase-1

The poor solubility of hemin in neutral aqueous solution and organic solvents limits its application. In order to cope with this problem, β-cyclodextrin-hemin complex by combining an outstanding embedding medium β-cyclodextrin (β-CD) with hemin was successfully synthesized and applied. Previous result showed that β-CDH might be through HOI-dependent mechanism and calcium signaling inducing the cucumber adventitious rooting. Moreover, heme oxygenasel (HO1) and nitric oxide (NO) are two important signaling molecules in the plant root system development. Herein, our further test β-CDH could induce tomato lateral root formation, and the role of HOI and NO in lateral root development. Our results showed that:1. β-CDH improved the bioavailability of hemin. P-CDH has a does-dependent induction of tomato lateral root formation. Compared with P-CD and hemin,we found that hemin (10 μM) has a significant effect on the induction lateral root formation. And other compounds have no function. We compared the effective concentrations of β-CDH (1 nM) and hemin (10μM), founded that β-CDH improved the bioavailability of hemin.2. HOI might be related to β-CDH-induced NO-mediated LR formation.1) β-CDH-induced NO production and thereafter HOI gene expression exhibited a time-dependent fashion in tomato seedlings. Afterwards, corresponding LR formation was observed.2) Similar to the positive control, hemin, the SIHO1 mRNA and/or its protein level were up-regulated by β-CDH and SNP, respectively. Besides these trends were strongly impaired by the presence of the HOI inhibitor, ZnPP, the increased SIHO1 transcripts were also separately blocked by the inhibition of NO production when PTIO was cotreated. These results confirmed the involvement of HOI in β-CDH-induced LR development, and suggested that tomato HO1 gene acts downstream of NO signaling.3. β-CDH could activate the cell cycle genes expression. The above mentioned up-regulation of representative cell cycle regulatory genes was significantly blocked when seedlings were cotreated by PTIO or ZnPP together with P-CDH. A similar reduction in above transcripts was also observed in the combination with SNP and PTIO or ZnPP. These counteracting responses corroborated a reduction of LR density and number, suggesting that NO-mediated HO1 favors LR formation by the modulation of cell cycle regulatory genes.In conclusion, by using the pharmacological and molecular revealed that β-CDH not only improved the bioavailability of hemin, but also showed that P-CDH could activate the cell cycle genes expression before regulate NO and HO1 in lateral root formation signal transduction in tomato.