| Betalains are responsible mainly for the attractive natural display of flower,fruit,and storage root color.They are water-soluble and nitrogen containing pigments.Amaranthin is one of them.It can be widely used in food additives,cosmetics and other industries.In addition,amaranthus has extensively adaptability in most regions in China.Induction of amaranthin accumulation has commonly been used as a rapid,effective biological assay for cytokinin activity.In this paper,with Amaranthus mangostanus L.as the material,we explored the stability of acid or alkali-dissolved solutions of kinetin in different storage conditions.When stored at room temperature for 21 days,acid-dissolved and alkali-dissolved kinetin solutions(10 mg/L)reduced the contents of amaranthin to 45.5%and 34.3%that of the corresponding controls.Activity of kinetin reduced more than 50%both in the two dissolved methods,but there was no significant difference between the two methods.Amaranthin contents induced by 10 mg/L kinetin solutions(acid and alkali-dissolved)after stored at 55 ? for 14 days were 29.6%and 26.4%that of their respect controls.Difference between them was not significant.At the same time,when solutions were stored at-20 ? for 21 days,there was no obvious degradation in kinetin activity.Light triggers the initiation of amaranthin biosynthesis in cotyledons of Amaranthus mangostanus L.Cytokinins is known to induce amaranthin synthesis in darkness or stimulate amaranthin accumulation under light induction.On basis of the amaranthin test,in this paper,Amaranthus mangostanus L.was chosen as the material to study the interactions between different plant growth regulators.We found that indole-3-acetic acid(IAA),a natural bioactive auxin,inhibited either kinetin or light-induced synthesis of amaranthin.In darkness,IAA at 10 mg/L caused 68%reduction of amaranthin production induced by 5 mg/L kinetin.While in light,the presence of 10 mg/L IAA resulted in a decrease of 56.4%or 50%amaranthin accumulation induced by 0 or 5 mg/L kinetin.Our results suggested that IAA had no effect on amaranthin accumulation in darkness,but it showed an antagonistic effect on light or cytokinin-induced amaranthin accumulation in cotyledons of Amaranthus mangostanus L.To study the effect of MeJA(Methyl Jasmonate)on amaranthin synthesis,we used Amaranthus mangostanus L.as material.For cotyledons of Amaranthus mangostanus L.,when in darkness,20 mg/L MeJA induced 10.91-fold amaranthin contents that of controls.While in light,presence of 20 mg/L MeJA resulted in 123%increment compared to cotyledons exposed to light only.When used 4-leaf stage seedlings as material,we found that MeJA could promote amaranthin accumulation in the seedlings including leafs and stems.But growth of the seedlings were inhibited by high concentrations of MeJA.From above,based on the amaranthin test,activity of acid/alkali-dissolved kinetin solutions both decreased when stored at 25 ? or at 55 ? for a couple of days,but difference between them was not significant.IAA could antagonize the light and kinetin effects on amaranthin synthesis in cotyledons of Amaranthus,the amaranthin synthesis in Amaranthus cotyledons may be used as an appropriate model for investigating the interactions between auxin and cytokinin as well.MeJA can promote amaranthin accumulation both in cotyledons and leafs,stems of Amaranthus mangostanus L.,but application of MeJA have inhibitory effect on growth and development. |
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