Functions Of Trigonelline On Plant Osmotic Adjustment

The active accumulation of solutes compatible with cellular metabolism is thought to play a central role in osmotic adjustment. Trigonelline, which is the N-methyl conjugate of nicotinic acid, has multiple functions like other plant secondary metabolites. But, trigonelline as osmolyte is not clearly understood. Two alfalfa cultivars ('Yuedongzhixing' and 'Kaisa') and two soybean cultivars ('Heinong No.38' and 'Suinong No.14') were used to studied changes of trigonelline concentration and osmotic adjustment during drought and salt stress. Trigonelline concentration was analyzed by HPLC performed at 264 nm. The results as follows:1. A method was proposed for the determination of the content of trigonelline in plants of alfalfa and soybean by HPLC. The sample was separated on Asahipak NH₂P-50 column with the mobile phase of acetonitrile-water (80:20, V:V) so that the content of trigonelline could be investigated rapidly and accurately. The content of trigonelline in seeds of alfalfa cultivars was higher than that of soybean, and alfalfa seeds could be used as material of trigonelline extraction.2. Leaf water potential(ψ_w) decreased during drought salt stress. Free proline accumulation, the commonest osmolyte, is an innate response of many plants to osmotic stress. Proline is accumulated, and osmotic adjustment (OA) increased with drought and salt. Trigonelline concentration increased significantly under drought and salt stress.3. The water and osmotic potentials were reduced with increase of salt concentration. The water potential of non stress treatments in leaves of 'Yuedongzhixing' and 'Kaisa' were -0.35 MPa and 0.33 MPa, and osmotic potential -0.54 MPa and 0.50 MPa. Water potentials of in leaves of 'Yuedongzhixing' and 'Kaisa' were -4.02 MPa and -3.83 MPa under salt concentration 400 mmo1·L^-1. The osmotic potentials in leaves of 'Yuedongzhixing' and 'Kaisa' were -4.05 MPa and -3.82 MPa. The content of trigonelline in leaves of plants increased with salt density. The content of trigonelline of CK in leaves of 'Yuedongzhixing','Kaisa', 'Heinong No.38' and 'Suinong No.14' was 22.31, 21.09, 30.67 and 31.15μg·g^-1Fw, respectively. The content of trigonelline in leaves of 'Yuedongzhixing', 'Kaisa', 'Heinong No.38' and 'Suinong No.14' was 63.63, 56.57, 73.21, 68.57μg·g^-1FW, respectively under salt concentration 400 mmo1·L^-1. The content of proline and soluble sugar increased with salt concentration in the leaves of the plant.When water and osmotic potentials decreased significantly under the drought and salt stress, the plant has accumulated osmolyte. As we known, the plant would accumulate proline and soluble sugar in the body under stress. In this study, it was indicated that trigonelline was accumulated in the plant under drought and salt stress as a kind of osmolyte. Trigonelline could be used as one index of resistance to stress in the plant.