--D.J. Hole, P.S. Hole, M.C. Drew and B.G. Cobb
Wild type root tips from the inbred line Tx5855 and from Adh1-null
seedlings (seeds were originally provided by R. Ferl, Univ. of Florida
and had been backcrossed 3 times into Tx5855) were hypoxically pretreated
(HPT, 4.0% O2 for 16 hrs.) and non-hypoxically pretreated (NHPT, 40.0%
O2 at 25 C) then placed under anoxic (100% N2) conditions. Evolution of
CO2 and ethanol were monitored for 5 hours (Table). In both wild type and
Adh1-null root tips, HPT tissue consistently metabolized
more glucose and produced more ethanol and CO2 than NHPT root tips indicating
that the low oxygen treatment is necessary to permit acclimatization of
the tissue to anoxic conditions. Interestingly, there were no noticeable
differences in the production of ethanol or CO2 between WT and Adh1-null
root tips in any treatment. ADH activity was assayed using the method of
Rumpho and Kennedy (Plant Phys. 68:165-168), and although ADH activity
was detected in wild type root tips, no activity was detected in the Adh1-null
root tips. The rate of production of ethanol was the same for both tissues
indicating that the in vitro assay does not equally detect both ADH1 and
ADH2. It is important to note that HPT Adh1-null root tips
carried out anaerobic respiration at the same rate as HPT wild type tips
suggesting that Adh2 may play a more important role in anaerobic
metabolism in cells acclimated to low oxygen levels than we have previously
thought.
|
|
||
| NHPT | HPT | |
| Tx5855 | 298 | 397 |
| Adh1-Tx5855 | 314 | 384 |
| Ethanol production (nmol EtOH g FW-1 h-1) | ||
| NHPT | HPT | |
| Tx5855 | 5.65 | 9.18 |
| Adh1-Tx5855 | 4.16 | 8.31 |
Please Note: Notes submitted to the Maize Genetics Cooperation Newsletter may be cited only with consent of the authors
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