USDA - Kentucky Report (Annual Report to SERA-IEG 8, Tall Fescue Toxicosis/Endophyte Workshop)

Authors: Klotz, James; BUSH, L - University Of Kentucky; Strickland, James; WEST, CHARLES - University Of Kentucky; Dinkins, Randy

Submitted to: SERA-IEG 8
Publication Type: Other
Publication Acceptance Date: 8/26/2009
Publication Date: 10/4/2009
Citation: Klotz, J.L., Bush, L.P., Strickland, J.R., West, C.P., Dinkins, R.D. 2009. USDA - Kentucky Report (Annual Report to SERA-IEG 8, Tall Fescue Toxicosis/Endophyte Workshop). SERA-IEG 8. p 62-66.

Interpretive Summary: A method is being developed that permits the evaluation of contractile responses of ruminal arteries and veins to various compounds, with particular interest in ergot alkaloids. Because these blood vessels are different from peripheral vessels that have been previously investigated, certain aspects of this new model required validation. The objective of this experiment was to determine if the contractile responses of the right ruminal artery and vein to increasing concentrations of either norepinephrine or serotonin are different when equilibrated to resting tensions of either 0.5 or 1.0 g. Results demonstrated that both the artery and vein responded to norepinephrine and serotonin and that there was no difference in response between the two different levels of resting tension. This indicates that the neither vessel type was overstretched during the equilibration phase of the method. In order to test different NE line clone pairs under stress treatments, we first had to recover genetically identical tall fescue plants with and without the endophyte. Seeds from 9 different lines containing NE combinations, and seeds from KY31 containing the ARK + endophyte (CE) were provided by Dr. Charles West. Tillers from each plant were separated and re-planted, each labeled to maintain identity to the originating NE id/plant id. Single tillers from the above plants were submerged in aerated containers containing fungicide for 7 days. Surviving tillers were separated and DNA isolated. PCR was performed to confirm the presence or absence of the endophyte using endophyte specific primers. Single plant derived tillers found to be endophyte negative were kept with the positive parental plant and constitute a clone pair. The fungicide treatment to date has resulted in the production of at least 6 clone pairs for all NE lines. These plants are presently being propagated in order to obtain sufficient number of tillers to use in water stress experiments.

Technical Abstract: A method is being developed that permits the evaluation of contractile responses of ruminal arteries and veins to various compounds, with particular interest in ergot alkaloids. Because these blood vessels are different from peripheral vessels that have been previously investigated, certain aspects of this new model required validation. The objective of this experiment was to determine if the contractile responses of the right ruminal artery and vein to increasing concentrations of either norepinephrine or serotonin are different when equilibrated to resting tensions of either 0.5 or 1.0 g. Results demonstrated that both the artery and vein responded to norepinephrine and serotonin and that there was no difference in response between the two different levels of resting tension. This indicates that the neither vessel type was overstretched during the equilibration phase of the method. In order to test different NE line clone pairs under stress treatments, we first had to recover genetically identical tall fescue plants with and without the endophyte. Seeds from 9 different lines containing NE combinations, and seeds from KY31 containing the ARK + endophyte (CE) were provided by Dr. Charles West. Tillers from each plant were separated and re-planted, each labeled to maintain identity to the originating NE id/plant id. Single tillers from the above plants were submerged in aerated containers containing fungicide for 7 days. Surviving tillers were separated and DNA isolated. PCR was performed to confirm the presence or absence of the endophyte using endophyte specific primers. Single plant derived tillers found to be endophyte negative were kept with the positive parental plant and constitute a clone pair. The fungicide treatment to date has resulted in the production of at least 6 clone pairs for all NE lines. These plants are presently being propagated in order to obtain sufficient number of tillers to use in water stress experiments.