A STUDY OF THE CELL-WALL MECHANICAL-PROPERTIES IN UNHYPERHYDRATED SHOOTS OF OREGANO (ORIGANUM VULGARE) INOCULATED WITH PSEUDOMONAS SP. BY LOAD DEFORMATION ANALYSIS

Elite oregano clonal lines are being targeted by our laboratory for fo od preservative and nutraceutical applications. Oregano (Origanum vulg are) shoot clones inoculated with Pseudomonas sp. resulted in increase d phenolics, reduced hyperhydricity, better tolerance to environmental stress and better adaptability when compared to uninoculated control. In order to confirm the qualitative and biochemical observations rela ted to potential lignification and cellulose build up, we have conduct ed mechanical load deformation analysis using a TEXTURE ANALYZER (exte nsometer) instrument after killing the shoots in boiling methanol and thereby removing the internal turgor pressure, instead of directly qua ntifying the lignin content by chemical methods. Protocol in this stud y was different in that we have used peak force upon rupture, breaking strain, deformability modulus and toughness parameters as the key cri teria for demonstrating whether Pseudomonas - induced unhyperhydrated shoots were stronger than the control (hyperhydrated) shoots. The diff erences in the bulk mechanical properties in hyperhydrated and unhyper hydrated shoots was very small except for deformability modulus which was somewhat higher to form a weakly positive explanation for the pote ntial of higher lignification in the inoculated shoots. Though our dec ision on whether the inoculated shoots were stronger than the control shoots was inconclusive, our protocol is' very useful to other laborat ories involved in similar studies. This will be particularly useful if the samples do not have very closely competitive properties and there fore the distinguishing features of the protocol and the statistical a ccuracy in measurements will be clearly evident.