茭白肉质茎膨大期间的氧化胁迫

以＂雄茭＂为参照,研究了茭白肉质茎膨大期间的氧化胁迫状况。肉质茎膨大开始后,茎中H2O2和MDA含量快速上升,并分别在6和8d达到最大,约为膨大前的6.5倍和3.7倍,此后降至膨大初期水平。抗坏血酸（AsA）在肉质茎即将膨大前上升约30%,但膨大后快速下降处于较低水平,为0d的25%～30%。氧化型抗坏血酸比例在膨大开...

OXIDATIVE STRESS DURING STEM ENLARGMENT OF Zizania latifolia Turcz.

Enlargement of succulent stem of Zizania latifolia Turcz. was accompanied by proliferation of smut fungus (Ustilago esculenta P. Henn.) and hyperplastic growth of the first 3 to 5 nodes beneath the apical meristem. This process was found to be preceded by rapid increase of H2O2 and MDA contents, reaching maxima at 6d and 8d, respectively, and followed by decline to their initial levels. Ascorbate (AsA) content was raised by ~30% before enlargement but dropped quickly to a lower level afterwards (about 25~30% of 0d, whereas the ratio of dehydroascorbate in total ascorbate maintained at a high level during enlargement. GSH content took a similar time course as that of AsA. The uppermost part of non-enlargingstems of the plant, the so-called "Xiongjiao", contained similar or lower levels of MDA, H2O2, AsA and GSH, as compared to those in the pre-enlargement state of succulent stem. Similar to the non-enlarging stems, mature leaves were also not infected by U. esculenta and relatively small fluctuations occurred in MDA and GSH levels during period of stem enlargement taking place in the same tiller. These results showed that the systematic smut fungus caused a progressive oxidative stress in the succulent stem, and antioxidants such as AsA and GSH probably contribute little to the scavenging of ROS during stem enlargement of Z. latifolia.