Analysis of apoplast pH as a factor for regulating fruit development and maturation of persimmon.

柿果实质外体酸性转化酶能将进口蔗糖降解为己糖(葡萄糖和果糖)，是柿果实在生长期III发育成熟的重要因素。果质外体酸性转化酶的活性似乎受多种因素的调节，尤其是质外体中的pH和糖浓度。本研究试图弄清果实质外体的糖组成和pH值，以及质外体酸性转化酶作为调节果实发育和成熟的一个因子的性质。通过加压脱水技术，去除第一批似被韧皮部流体污染的40份样品，即可获得质外体液质体液。质外体中的糖主要由己糖(葡萄糖和果糖)占据，而不是蔗糖，尽管果实的糖分积累类型不同。蔗糖积累型和己糖积累型品种的质外体中都只有己糖。在生长期III，摘除果实的花瓣会显著抑制果实的发育和成熟。与此相一致的是，果实没有表现出质外体中己糖浓度和酸性转化酶活性的增加。这些结果表明质外体中的糖代谢在果实发育和成熟过程中起着重要作用。质外体的pH值在6.5左右，不是酸性转移酶活性的最适pH。转化酶的最适pH为4.5左右。尽管这一结果似乎表明质外体的pH不是质外体转化酶活性的调节因素，但有可能是质外体中的pH不均匀。我们应该更详细地调查这一点。

The degradation of imported sucrose to hexoses(glucose and fructose)by acid invertase at apoplast of the fruit is an important factor for development and maturation of the fruit during growth stage III of persimmon. The activity of acid invertase at apoplast of the fruit seems to be regulated by several factors, especially pH and sugar concentration in the apoplast. We attempted in this project to make clear the sugar composition and pH of apoplast in the fruit and to characterise the properties of acid invertase at the apoplast as a factor for regulating fruit development and maturation.1. The apoplast fluid could obtain by pressure dehydration techniques by removing the first obtained 40mul sample, which seemed to be contaminated by phloem fluid.2. Sugar of apoplast was occupied mainly by hexoses(glucose and fructose), not by sucrose, despite sugar-accumulating types of the fruit. Both sucrose-and hexose-accumulating cultivars showed to have only hexoses in their apoplast.3. Calyx lobe removal of the fruit remarkably inhibited development and maturation of the fruit during growth stage III.Coincident with this inhibition, the fruit did not show the increase of hexose concentration and activities of acid invertase in apoplast. These results showed an important role of sugar metabolism in apoplast on fruit development and maturation.4. The pH of apoplast showed around 6.5 which was not the optimum pH for acid invertase activity. The optimum pH of invertase activity were around 4.5. Although this result seems to indicate that pH of apoplast is not a regulating factor of invertase activity at apoplast, there is a possibility that the pH is not uniform in apoplast. We should investigate this point in more detail.