Abstract:

Objective: Nitrogen is one of macroelements necessary for plant growth and development,and ammonium nitrogen is one of the main nitrogen sources available for roots. Ammonium transporter(AMT) plays an important role in the acquisition and transport of ammonium nitrogen. Fast growth is the most important feature of Moso bamboo(Phyllostachys edulis). The identification of AMT genes in Moso bamboo,and the systematic analysis of their structures and expression patterns will lay the foundation for in-depth study on the function of AMT genes in rapid growth of Moso bamboo and its environmental adaptability. Method: Bioinformatics methods were used to identify the gene members of AMT family in Moso bamboo. Furthermore,their phylogeny,structural characteristics,tissue expression specificity,and responses to hormones and abiotic stresses were analyzed,and the expression patterns of key genes under drought treatment were verified by qPCR. Result: A total of 13 AMT family genes were identified in the genome of Moso bamboo,named PeAMT1-PeAMT13. The proteins encoded by PeAMTs were 408-497 amino acids in length,and the subcellular localization prediction showed that all PeAMTs were located on the plasma membrane. Phylogenetic analysis showed that PeAMTs were divided into two subfamilies,and each of which had its own specific motifs,but all PeAMTs contained the typical conserved sequence in Motif 2 of ammonium transporters. The collinearity analysis showed that eight pairs of PeAMTs had collinearity,and 11 PeAMTs had collinearity with eight OsAMTs. PeAMTs were subjected to purification selection. PeAMTs had tissue expression specificity,most of which had the highest expression level in roots and leaves,followed by shoots at early stage of growth,and lower expression levels in shoots with higher lignification at late stage of growth. A variety of hormones and abiotic stress response elements were found in the promoter of PeAMTs. The treatments of GA₃,brassinolide(BL) and drought all caused significant changes in the expression of most PeAMTs,and NAA and low temperature treatments also resulted in significant expression changes of six PeAMTs(P < 0.05). The key genes PeAMT1,PeAMT2,and PeAMT3 were screened for qPCR verification under drought treatment,and the expression changes of the three genes reached significant levels(P < 0.05). Conclusion: There were 13 PeAMTs encoding complete AMT in Moso bamboo,which had certain differences in structural characteristics and tissue expression specificity,and their expression was affected by hormones and abiotic stresses. PeAMTs might help Moso bamboo to obtain ammonium nitrogen from the soil by a high expression in the roots,and transfer and recycle ammonium nitrogen in the leaves with a high expression to ensure sufficient nitrogen supply during the rapid growth of Moso bamboo. Meanwhile,PeAMTs might function in ammonium detoxification for improving the resistance of Moso bamboo.

Key words: Phyllostachys edulis, ammonium transporter, molecular characteristics, gene expression