The lotus NnWOX1-1、NnWOX4-3 and NnWOX5-1 promoted root formation and enhanced stresses tolerance in transgenic Arabidopsis thaliana

Abstract Background: Adventitious root (AR) is an important organ in water and nutrition uptake in lotus due to degeneration of principle root. Wox is involved in regulating plant development and growth by affecting multiple genes expression in plant kingdom. In this study, three genes including NnWOX1-1、NnWOX4-3 and NnWOX5-1were isolated, and genes function was assessed in Arabidopsis plants. Results: The full-length of the NnWOX1-1、NnWOX4-3 and NnWOX5-1 were 1038 bp, 645 bp and 558 bp in nucleotide, and encoded 362, 345 and 185 amino acid residues respectively. Phylogenetic analysis showed that Nnwox1-1 and Nnwox4-3 was classified into one group, and Nnwox5-1 and Mnwox5 showed high genetic relationship. These three genes were all induced by sucrose and IAA, and had organ-specific expression characteristic. Aside from the improvement of root growth and salt tolerance, NnWOX1-1 and NnWOX4-3 could also promote stem development in transgenic Arabidopsis. A total of 751, 594 and 541genes including nineteen, nineteen and thirteen genes related with ethylene and IAA metabolism and response were enhanced expression in NnWOX1-1、NnWOX4-3 and NnWOX5-1 transgenic plants respectively. Further analysis showed that ethylene product rates was increased, and while IAA, POD and lignin content were no significantly changed. Exogenous application of ethephon promoted ARs formtion and dramaticly increased fresh weight and dry weight of lotus seedlings. Conclusions: NnWOX1-1、NnWOX4-3 and NnWOX5-1 was involved in root formation, stem development and stresses adaptation in transgenic Arabidopsis plants by affecting multiple genes transcriptation. Among which, the change of genes expression in ethylene metabolism and respondings probably exerted criticle role on development in Arabidopsisplant. In addition, ethylene might be an important factor to affect ARs formation in lotus seedlings.