Expression of the BTB/POZ domain-containing protein At1g63850-like gene CsFDI1 is enhanced by sugar starvation in cucumber fruit

摘要

The cDNA of Cucumis sativus Fruit Defoliation Induced 1 (CsFDI1) was newly cloned using the subtraction method from a fruit of a defoliated cucumber (Cucumis sativus L. cv. Tokiwa) plant. An expression analysis of CsFDI1 in fruits and leaves was conducted along with those of the asparagine synthetase 1-like gene (AS) and Cucumis sativus Somatic Embryogenesis Zinc Finger 1 (CsSEF1), previously reported as control marker genes for sugar starvation. The transcript level of CsFDI1 and AS was relatively high, whereas that of CsSEF1 was very low under normal fruit development. The time course of the transcript levels of the three genes under prolonged darkness was compared with that of the fruit respiration rate and leaf starch concentration. The fruit respiration rate suggested that photoassimilate translocation to fruit ceased abruptly under prolonged darkness. The transcript level of CsFDI1, AS, and CsSEF1 increased in fruits, but the time course of the change was quite different in fruits and leaves under the condition of sugar starvation. The response of AS in leaves and CsSEF1 in fruits was close to all-or-none.