High Light and Low Temperature Effect on D1 Synthesis and Turnover in the Chilling Sensitive Plant Lycopersicun Esculentum

80 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2002.Photoprotective mechanisms of a plant can become overwhelmed when high light is combined with low temperature. In the chilling sensitive plant tomato (Lycopersicun esculentum var. Mill Floramerica), these combined stresses were found to cause a decrease in de novo synthesis of D1, a component of photosystem II (PSII) reaction center which is known to be damaged by high light. The decrease in D1 synthesis was not due to changes in the steady state level of psbA, D1 message. An increase in psbA mRNA association with ribosomes along with pausing during elongation of translation was observed. These pause sites were found to be the same as control conditions indicating that the decrease in D1 synthesis was not due to low temperature adversely affecting translation but rather its having a negative impact elsewhere in the repair of the damaged protein. The turnover of D1 was found to be at a slower rate than the control. In addition, an increase in the accumulation of the primary degradation fragment was observed. Further investigation revealed that the damaged PSII reaction center is not migrating from the grana.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD