Growth and development of juice vesicles grown by in vitro culture in Citrus

柑桔汁囊泡的体外培养有助于柑桔果实糖酸代谢的研究。本研究在MS固体培养基上，在25℃的黑暗条件下，对柑桔幼果的果汁囊泡（包括一些中果皮组织）进行了体外培养。果汁小泡膨胀并变成橙色。在添加10%蔗糖的培养基上培养2个月后，果汁囊泡积累的糖和分解的酸与田间生长的水果相似。在开花后51天或更晚从果实中取出的汁囊外植体在培养基上培养时发生了糖积累。测定了蔗糖、葡萄糖和果糖对囊泡生长和糖积累的影响。果糖对囊泡生长无明显影响。在不同蔗糖浓度和水势的培养基上培养果汁囊泡外植体。在调节水势或不调节水势的条件下，囊泡积累的糖和酸与培养基中蔗糖含量呈正相关。在10%蔗糖浓度的不同水势条件下培养，随着水势的降低，汁囊的生长减少，糖和酸的积累增多。3 .在不同氮水平培养基上培养汁囊外植体时，汁囊糖含量与培养基中氮含量呈负相关，汁囊酸含量与培养基中氮含量呈正相关。不同碳水化合物培养的囊泡中的糖组成表明糖在囊泡外植体中发生了降解和转化。培养的果汁泡中糖代谢酶SS、SPS和蔗糖转化酶活性高于田间果实，但两种果实中这些酶活性的季节变化相似

The in vitro culture of juice vesicles could aid in studies on the sugar and acid metabolism in citrus fruit. In this report, juice vesicle explants including some mesocarp tissue excised from young satsuma mandarin (Citrus unshiu Marc.) fruit, were cultured in vitro on MS solid medium under dark conditions at 25 C.1. The juice vesicles grew expansively and turned orange. The juice vesicles accumulated sugar, and disintegrated acid similar to those of fruit grown in the field when cultured on the medium supplemented with 10 % sucrose and incubated for two months. Sugar accumulation occurred in the juice vesicle explants excised from fruitlet at 51 days after full bloom or later and cultured on the medium. Effect of sucrose, glucose and fructose on vesicle growth and sugar accumulation was determined. Fructose was not effective for vesicle growth.2. Juice vesicle explants were cultured on medium with various sucrose concentrations and water potentials. There is a close positive relationship between sugar and acid accumulated by vesicles and sucrose content in the medium with or without adjusting water potential. When cultured under different water potentials on 10 % sucrose concentration, the juice vesicles grew less but accumulated more sugar and acid as the water potential decreased.3. When juice vesicle explants were cultured on medium with various nitrogen levels, there is a negative relationship between sugar content of juice vesicles and nitrogen content in the medium, but a positive one between acid content of juice and nitrogen in the medium.4. Sugar composition in vesicles cultured on various carbohydrates indicates sugar degradation and conversion occurred in vesicle explants. Activities of sugar metabolizing enzymes, SS, SPS and Invertase, were higher in cultured juice vesicles than those of fruit grown in the field, however, the seasonal changes of those enzyme activities in both fruits were similar