Submitted to: Annals Of Botany
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/10/2005
Publication Date: 5/20/2005
Citation: Livingston, D.P., Premakumar, R., Tallury, S.P. 2005. Carbohydrate concentrations on sub-fractions of winter oat crowns during second phase hardening. Annals Of Botany. 96:331-335. Interpretive Summary: Contradictory results have been reported when various biochemical changes in cold hardened plants were related to freezing tolerance. These contradictions may be because most experiments extract compounds from tissue that is not the same tissue surviving a freeze treatment. The crown of winter cereals such as wheat, barley and oats, is the lower part of the stem that survives winter. We have shown that differences exist in the ability of cells within oat crowns to survive. Therefore, averaging biochemical changes, by grinding whole crowns, is invalid when trying to relate biochemical adaptation during cold hardening to freezing tolerance. In this study we developed a technique to separate tissue in the lower part of oat crowns. We found that in the more freezing tolerant tissue, sugars that are important in freeze protection as well as proteins change during cold hardening to a greater extent than in less hardy tissue. Biochemical changes in plants are a reflection of their genetics and therefore this technique will probably provide a more accurate picture of how plants overcome freezing during winter.
Technical Abstract: Carbohydrate measurement in the whole crown while cold hardening occurs primarily in meristematic tissue within the crown may result in correlations with freezing tolerance that are contradictory. To evaluate whether carbohydrate and protein changes in oat crowns during second phase hardening (2PH) are tissue specific, the lower portion of the crown was exposed to a mild grinding treatment in a blender. The remaining crown meristem (CM) complex, consisting of tough root-like vessels, was ground in a device developed specifically for cereal crown tissue. Changes in carbohydrates and total protein were compared in the two regions of the crown during 2PH. Fructan of all size classes except DP>6, decreased during 2PH in both stem and CM complex. Total simple sugar increase, including sucrose, during 2PH was significantly higher in the CM complex than in the stem. Total protein increase during 2PH was also significantly higher in the CM complex than in stem tissue. The differences demonstrated here support the hypothesis that carbohydrate and protein change in mildly frozen plants is tissue specific within crown tissue.