Molecular cloning, expression profiles, characterization and function of a novel arginine decarboxylase gene (HbADC2) in Hevea brasiliensis

As a major industrial raw material, natural rubber (NR) is also an important strategic material. Commercial NR is almost exclusively produced from rubber tree latex at present. Given that polyamines (PAs), especially putrescine (Put), can accelerate NR biosynthesis by scavenging ROS in laticifers, arginine decarboxylase (ADC) is likely involved in ROS balance by regulating Put content. In the present study, HbADC2, a novel ADC gene, was cloned and analyzed in detail. HbADC2 were expressed in different tissues and developmental stages of leaves, suggesting that HbADC2 was involved in rubber tree growth and development. As a multifunctional gene, HbADC2 was also modulated by several stresses and hormone treatments. Put contents were consistent with the expression levels of HbADC2 in latex between healthy rubber tree and tapping panel dryness (TPD)-affected one, implying that HbADC2 was likely associated with Put biosynthesis in rubber tree. In addition, tobacco plants overexpressing HbADC2 can enhance tolerance to methyl viologen (MV)-induced oxidative stress by increasing Put biosynthesis to decrease hydrogen peroxide (H2O2) content. Taken together, our results suggest that HbADC2 not only is related to rubber tree growth, TPD, development, stress and hormone responses, but also enhances the tolerance to MV-induced oxidative stress by increasing Put biosynthesis in tobacco plants.