Response of MaHMA2 gene expression and stress tolerance to zinc stress in mulberry(Morus alba L.)

HMA2(heavy metal ATPase 2)plays a crucial role in extracellular and intracellular Zn^(2+)transport across biomembranes,maintaining ion homeostasis,and playing an important role in the normal physiological metabolism,growth,and development of plants.In our study,a novel HMA2 gene,named MaHMA2,was isolated and cloned from white mulberry(Morus alba L.).The gene sequence obtained was 1,342 bp long,with an open reading frame of 1,194 bp,encoding a protein of 397 amino acids,with a predicted molecular mass of 42.852 kD and an isoelectric point of 7.53.This protein belonged to the PIB-type ATPase transport protein family.We analyzed the expression of the MaHMA2 gene by quantitative real-time PCR.The results showed that the level of MaHMA2 gene expression decreased to a Zn concentration of 800 mg/kg.Malondialdehyde and proline levels increased and responded to increasing Zn when the MaHMA2 gene was silenced,whereas the activities of peroxidase and superoxide dismutase tended to increase in response to increasing Zn^(2+)ion stress concentrations but were lower in the gene-silenced plants.These findings suggested that the MaHMA2 gene played an active role in the tolerance response of mulberry to Zn stress.

Genome-wide analysis of microRNAs induced and regulated by colchicine in mulberry

A variety of plants were colchicine treated to double their chromosome number.Chromosomes are genetic carriers that determine the individual traits of organisms.The doubling of chromosomes will lead to modifications in plant morphology,physiology and genetics.To determine the response of mulberry trees induced by colchicine,using mulberry variety Yu-711 leaves as research materials,two small RNA libraries(control and experimental groups)were constructed.It was found that 45 known miRNA genes and 78 predicted novel miRNA genes in the sequence results.A comparison of data between the control group and the experimental group revealed 37 differentially expressed miRNA genes,19 genes of which were up-regulated and 18 genes of which were down-regulated.Eight miRNAs were selected from 37 differentially expressed miRNA genes.These miRNAs were verified by quantitative real-time PCR,and the expression levels of these miRNAs were found to be consistent with those obtained by sequencing,which proved the accuracy of sequencing results.The PsRNATarget software was used to predict the target genes of 8 miRNAs.The Gene Ontology and Kyoto Encycopedia of Genes and Genomes analysis were used to collect the functions of target genes and confirm that target genes are mainly involved in biological processes,cell components and molecular functions.novel-77 miRNA was selected from 37 differentially expressed miRNAs.What will serve as a fundamental data in understanding mulberry miRNAs function in molecular biology research and further provides the molecular mechanism of mulberry gene regulation as induced by colchicine is that the prediction of novel_77 precursor sequence and the target gene(XM_010104258.2),as well as the secondary structure analysis.