To gain insight into the response of mulberry to phytoplasma-infection, the expression profiles of mRNAs and proteins in mulberry phloem sap were examined. A total of 955 unigenes and 136 proteins were found to be differentially expressed between the healthy and infected phloem sap. These differentially expressed mRNAs and proteins are involved in signaling, hormone metabolism, stress responses, etc. Interestingly, we found that both the mRNA and protein levels of the major latex protein-like 329 () gene were increased in the infected phloem saps. Expression of the gene was induced by pathogen inoculation and was responsive to jasmonic acid. Ectopic expression of in Arabidopsis enhances transgenic plant resistance to , pv tomato DC3000 ( DC3000) and phytoplasma. Further analysis revealed that can enhance the expression of some defense genes and might be involved in altering flavonoid content resulting in increased resistance of plants to pathogen infection. Finally, the roles of the differentially expressed mRNAs and proteins and the potential molecular mechanisms of their changes were discussed. It was likely that the phytoplasma-responsive mRNAs and proteins in the phloem saps were involved in multiple pathways of mulberry responses to phytoplasma-infection, and their changes may be partially responsible for some symptoms in the phytoplasma infected plants.

The quality and quantity of mulberry leaves are often affected by various environmental factors. The plant NPR1 and its homologous genes are important for plant systemic acquired resistance. Here, the full‐length cDNAs encoding the NPR1 and NPR4 genes (designated MuNPR1 and MuNPR4, respectively) were isolated from Morus multicaulis. Sequence analysis of the amino acids and protein modeling of the MuNPR1 and MuNPR4 proteins showed that MuNPR1 shares some conserved characteristics with its homolog MuNPR4. MuNPR1 was shown to have different expression patterns than MuNPR4 in mulberry plants. Interestingly, MuNPR1 or MuNPR4 transgenic Arabidopsis produced an early flowering phenotype, and the expression of the pathogenesis‐related 1a gene was promoted in MuNPR1 transgenic Arabidopsis. The MuNPR1 transgenic plants showed more resistance to Pseudomonas syringae pv. tomato DC3000 (Pst. DC3000) than did the wild‐type Arabidopsis. Moreover, the ectopic expression of MuNPR1 might lead to enhanced scavenging ability and suppress collase accumulation. In contrast, the MuNPR4 transgenic Arabidopsis were hypersensitive to Pst. DC3000 infection. In addition, transgenic Arabidopsis with the ectopic expression of either MuNPR1 or MuNPR4 showed sensitivity to salt and drought stresses. Our data suggest that both the MuNPR1 and MuNPR4 genes play a role in the coordination between signaling pathways, and the information provided here enables the in‐depth functional analysis of the MuNPR1 and MuNPR4 genes and may promote mulberry resistance breeding in the future.

In the present study, the cDNA (designated MuPR1) of PR1 gene was obtained from mulberry. Our results showed that MuPR1 shares some conserved characteristics with its homologues from different plant families. MuPR1 was localized exclusively to the extracellular spaces, and the MuPR1