Salicylic acid-binding protein 2 (SABP2) is essential for the establishment of systemic acquired resistance (SAR) in tobacco; SABP2's methyl salicylate (MeSA) esterase activity is required in healthy systemic tissues of infected plants to release the active defense phytohormone SA from MeSA, which serves as a long-distance signal for SAR. In the current study, we characterize a new gene family from Arabidopsis thaliana encoding 18 potentially active α/β fold hydrolases that share 32-57% identity with SABP2. Of 14 recombinant AtMES (MES for methyl esterase) proteins tested, five showed preference for MeSA as a substrate and displayed SA inhibition of MeSA esterase activity in vitro (AtMES1, -2, -4, -7, and -9). The two genes encoding MeSA esterases with the greatest activity, AtMES1 and -9, as well as AtMES7 were transcriptionally upregulated during infection of Arabidopsis with avirulent Pseudomonas syringae. In addition, conditional expression of AtMES1, -7, or -9 complemented SAR deficiency in SABP2-silenced tobacco, suggesting that these three members of the AtMES family are SABP2 functional homologs (orthologs). Underexpression by knockout mutation and/or RNAi-mediated silencing of multiple AtMES genes, including AtMES1, -2, -7, and -9, compromised SAR in Arabidopsis and correlated with enhanced accumulation of MeSA in the systemic tissue of SAR-induced plants. Together, the data show that several members of the AtMES gene family are functionally homologous to SABP2 and redundant for MeSA hydrolysis and probably SAR. These data suggest that MeSA is a conserved SAR signal in Arabidopsis and tobacco.

The aim of current research is to analyze the effect of microfluidization on the stability and some quality characteristics of orange juice with respect to treatment pressure and cycle. Orange juice was microfluidized with four different pressures (34, 69, 103 and 138 MPa) and three different cycles (1, 2 and 3) at 18 &plusmn / 2 0C. Physical and chemical properties of microfluidized juices were compared with non-microfluidized freshly squeezed orange juice. Microfluidization made orange juice brighter and decreased redness and yellowness. There was a huge difference between non-microfluidized juice and microfluidized juice in terms of particle size. Microfluidization decreased the volume weighted mean (VWM) of orange juice between 90 % and 97 %. The results of total phenol content and antioxidant activity experiments showed that treatment pressure affected them positively / however cycle had not a significant effect on total phenol content and antioxidant property of orange juice (p&lt / 0.05). Our current research also includes effect of microfluidization on stability of orange juice. The broken down of aggregated structure and reduction in particle size due to treatment were observed by the scanning electron and light microscopes. Therefore, it was observed that treated orange juice could be homogeneous and opaque for 14 days at 4 0C. Cloud stability of juice showed that both pressure and cycle had important effect on the cloud stability (p&lt / 0.05). Microfluidization made the juice very stable but increase in pressure and cycle resulted in less stable juice. It was also measured that pectin methyl esterase activity was increased due to treatment of microfluidization.