コムギの登熟期における酸可溶性ヌクレオチドの体内分布と, 開花初期の穂切除の影響

抄録

Acid soluble nucleotides of wheat were surveyed at the one month after heading. They were extracted with cold perchloric acid and separated by chromatography on columns of Dowex 1(C1-), followed by repeated paper chromatography. The nucleotide compostition of wheat is presented in table 5. The detected nucleotides in the grain were adenosine monophosphate (AMP), adenosine diphosphate (ADP), ADP-glucose, ADP-X₁, ADP-X₃, adenosine triphosphate (ATP), uridine monophoshate (UMP), uridine diphosphate (UDP), UDP-glucose, UDP-X₃, uridine triphosphate (UTP), cytidine monophosphate (CMP) and guanosine derivatives. In leaves and culms, only AMP and ADP were detected. The total nucleotides were 12.39 μmoles in 75 g fresh weight of grains, while 0.35 μmoles in the leaves and culms. Thus, the contents of nucleotides in leaves and culms were approximately 3% of those in grains. ATP and ADP-sugar were not detected in leaves and culms. These nucleotides were probably decomposed to AMP and ADP during senescence. In grains, ADP- and UDP- sugars were main derivatives of adenosirle and uridine. ADP-sugar and UDP-sugar occupied 54% and 58% of respective nucleotides. As reported in the previous paper, rice contained UDP-glucose in the leaves and culms at the stage of one month after flowering, but wheat did not as described above. These differences may reflect that leaves and culms of rice are less senescent than those of wheat at this stage. Wheat, whose ears were cut off at the flowering stage, were grown further one month. The detected nucleotides from leaves arLd culms of these treated plants were AMP, ADP, ATP, UMP, UDP, UDP-glucose, UDP-X₃ and CMP. ADP-sugar and UTP which were detected in non-treated plants were not found in treated plants. The contents of nucleotides in treated plants were about 20% of those from the non-treated plants. Only AMP was greater in treated plants than in non-treated. Adenosine derivatives were predominant in treated plants. The treated plants contained less UDP-glucose and more AMP in their acid soluble nucleotide pool than non-treated plants. When ears were cut off, leaves and culms were probably substituted for ears to pool acid soluble nucleotides. Identification of the nucleotide sugar of fraction f, j and I (see figure 1) was tried. After mild hydrolysis with 20% acetic acid, several sugars were detected on paper chromatogram (see figure 3). Glucose (X₂), maltose (X₃) and fructose (X₁) were tentatively identified after comparison with R_f values (R_glucose values) of authentic samples.