Mediation of deep supercooling of peach and dogwood by enzymatic modifications in cell-wall structure Export

@article{citeulike:2971226, abstract = {Treatment of stem sections of peach (Prunus persica (L.) Batsch) and flowering dogwood (Cornus florida L.) with macerase, an enzyme mixture rich in pectinase, for 24–48 h resulted in a complete flattening of the low-temperature exotherm (LTE) as determined by differential thermal analysis (DTA). Ultrastructural analysis of macerase-treated tissue demonstrated a nearly complete digestion of the pit membrane (black cap and primary cell-wall) of nearly 100\% of the xylem-parenchyma cells examined after 48 h of exposure to the enzyme. Additionally, the underlying amorphous layer was partially degraded in up to 57\% of the cells examined. The macerase treatment had no visible effect on secondary cell-walls of xylem tissue. In contrast, treatment of stem tissue with cellulysin (mostly cellulase) resulted in a shift of the LTE to warmer temperatures as determined by DTA, and a digestion of only the outermost layer of the pit membrane in nearly 100\% of the cells examined, with little or no effect on the underlying layers. Treatment of tissue with 25 mM sodiumphosphate buffer also resulted in a shift of the LTE to warmer temperatures but the shift was not as great as in cellulysin-treated tissue. The shift was associated with a partial degradation of the outermost layer of the pit membrane in dogwood (33–45\% of the cells examined) but not in peach (3–7\% of the cells). Collectively, the data indicate that pectins may be an integral structural element of the pit membrane and that this portion of the cell-wall, along with the underlying amorphous layer, play a major role in forming a barrier to water movement and growth of ice crystals. This barrier allows xylem parenchyma of some species of woody plants to undergo deep supercooling.}, author = {Wisniewski, Michael and Davis, Glen and Schafter, Karen}, citeulike-article-id = {2971226}, citeulike-linkout-0 = {http://dx.doi.org/10.1007/BF01102426}, day = {1}, doi = {10.1007/BF01102426}, journal = {Planta}, keywords = {acclimation, anatomy, cellular, freezing, xylem}, month = {May}, number = {2}, pages = {254--260}, posted-at = {2008-07-08 00:41:20}, priority = {2}, title = {Mediation of deep supercooling of peach and dogwood by enzymatic modifications in cell-wall structure}, url = {http://dx.doi.org/10.1007/BF01102426}, volume = {184}, year = {1991} }

TY - JOUR ID - citeulike:2971226 L3 - citeulike-article-id:2971226 N2 - Treatment of stem sections of peach (Prunus persica (L.) Batsch) and flowering dogwood (Cornus florida L.) with macerase, an enzyme mixture rich in pectinase, for 24–48 h resulted in a complete flattening of the low-temperature exotherm (LTE) as determined by differential thermal analysis (DTA). Ultrastructural analysis of macerase-treated tissue demonstrated a nearly complete digestion of the pit membrane (black cap and primary cell-wall) of nearly 100% of the xylem-parenchyma cells examined after 48 h of exposure to the enzyme. Additionally, the underlying amorphous layer was partially degraded in up to 57% of the cells examined. The macerase treatment had no visible effect on secondary cell-walls of xylem tissue. In contrast, treatment of stem tissue with cellulysin (mostly cellulase) resulted in a shift of the LTE to warmer temperatures as determined by DTA, and a digestion of only the outermost layer of the pit membrane in nearly 100% of the cells examined, with little or no effect on the underlying layers. Treatment of tissue with 25 mM sodiumphosphate buffer also resulted in a shift of the LTE to warmer temperatures but the shift was not as great as in cellulysin-treated tissue. The shift was associated with a partial degradation of the outermost layer of the pit membrane in dogwood (33–45% of the cells examined) but not in peach (3–7% of the cells). Collectively, the data indicate that pectins may be an integral structural element of the pit membrane and that this portion of the cell-wall, along with the underlying amorphous layer, play a major role in forming a barrier to water movement and growth of ice crystals. This barrier allows xylem parenchyma of some species of woody plants to undergo deep supercooling. IS - 2 JF - Planta EP - 260 TI - Mediation of deep supercooling of peach and dogwood by enzymatic modifications in cell-wall structure VL - 184 SP - 254 KW - acclimation KW - anatomy KW - cellular KW - freezing KW - xylem AU - Wisniewski, Michael AU - Davis, Glen AU - Schafter, Karen PY - 1991/05/01/ UR - http://dx.doi.org/10.1007/BF01102426 ER -