f methanol and cis-3-Hexen-1-ol revealed a mouse preference for methanol. An analysis using the x22test confirmed a statistically significant difference in the preference of mice to methanol over cis-3-Hexen-1-ol. We did not detect methyl jasmonate in the headspace of wounded leaves. Ethylene emission was detected, but there was no statistically significant difference in ethylene emission between the control and wounded leaves. Nevertheless, we tested methyl jasmonate and ethylene, and the mice did not reveal any preference for these compounds over water vapors. The mice chose equally between water vapors. Furthermore, the mice did not prefer wounded or intact B. rapa leaves to methanol vapors. We concluded that the methanol emitted by plants may function as an attractant for mice. We then assessed the gene expression profile in the mouse brain after methanol inhalation. We studied the changes in the MRG expression patterns by determining mRNA levels in isolated mouse brain tissues 
by qRT-PCR. After the inhalation of methanol or wounded leaf vapors, the mRNA levels of mGAPDH, mTax1BP1 and mSNX27 increased in mouse brains, whereas mCycA2 mRNA was suppressed drastically. It is worth emphasizing that the changes in MRG mRNA levels after the inhalation of methanol or wounded leaf vapors were similar to those in the brain tissue of mice after pectin complex ingestion. We concluded that the methanol emitted by plants can be an attractant to mice and may induce the up- and downregulation of MRGs in mouse brain tissue. Discussion Many plants respond to wounding from pathogen and herbivore attacks by releasing airborne volatile compounds that serve as plant defenses involved in within-plant and plant-to-plant signaling, attracting natural enemies of the herbivores and repelling other herbivores. The reality of ��talking trees,��which describes plants’ expression of resistance mediated by VOCs from neighboring plants, is now well described. The idea of ��eavesdropping��has recently explained the evolutionary benefits and disadvantages for plant emitters, which mainly use VOCs for within-plant purposes. Chemical signals, such as ethylene, methyl salicylate, and methyl jasmonate, induce resistance to many pathogens. Pectin and PME form a ubiquitous multifunctional enzymatic complex in the plant cell wall and generate methanol by pectin demethylation. Since 1661, when Robert Boyle described methanol as a ��sowrish spirit�� using the pyrolysis of boxwood and distillation, the function of methanol in plant and animal life has been unclear. Although emissions from volcanoes, generation from H2 and CO2 in seafloor hydrothermal systems and the combustion of biomass all contribute to terrestrial atmospheric methanol, PME-mediated emissions from plants are likely the largest source of methanol in PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/22189542 the atmosphere. For a long time, gaseous Methanol as a Cross-Kingdom Signal methanol was considered a biochemical ��waste product”. Recently, we have studied the effects of PME-generated methanol from plants on the defensive reactions of plants. It was shown that increased methanol emission from PME-transgenic or mechanically wounded nontransgenic plants retards the growth of the bacterial pathogen Ralstonia solanacearum in neighboring ��Brivanib receiver��plants. Antibacterial resistance was accompanied by the upregulation of genes 7 Methanol as a Cross-Kingdom Signal 8 Methanol as a Cross-Kingdom Signal controlling stress and cell-to-cell communication in the ��receiver”. We con
