无花果果实韧皮部卸载路径由共质体向质外体途径转变  

A shift of phloem unloading from symplasmic to apoplasmic pathway during fig fruit development

作　　者：李春丽[1] 侯柄竹[2] 张晓燕[3] 李疆[1] 沈元月[2] 

机构地区：[1]新疆农业大学林学与园艺学院,乌鲁木齐830052 [2]农业应用新技术北京市重点实验室,北京农学院植物科学技术学院,北京102206 [3]中国农业大学生物学院,北京100094

出　　处：《科学通报》2016年第8期835-843,共9页Chinese Science Bulletin

基　　金：国家自然科学基金(31471837);北京市属高等学校创新团队建设与教师职业发展计划(IDHT20140509)资助

摘　　要：为了揭示无花果果实同化物韧皮部卸载机制,以玛斯义陶芬无花果5个时期果实为试材利用透射电子显微镜结合荧光染料示踪技术研究同化物韧皮部卸载路径的变化.无花果果实发育分3个时期,第1个快速生长期、缓慢生长期、第2个快速生长期,第2个生长期和第3个生长期之间为果实发育的转折期生长期之间.超微结构观察表明,无花果始熟期前筛分子伴胞复合体和周围薄壁细胞存在共质体联系,但始熟期后变为共质体隔离,同时在果实整个发育过程中薄壁细胞间始终存在大量胞间连丝.羧基荧光素(CF)引入表明,始熟期前荧光染料从韧皮部卸出到周围薄壁细胞中,在始熟期后CF被严格限制在韧皮部没有卸出到周围薄壁细胞.结果表明,无花果果实始熟期是同化物韧皮部卸载由共质体向质外体转变的转折期,但同时韧皮部后运输始终为共质体途径.To uncover the phloem unloading pathway of fig fruit, five-stage fruit of Masui Dauphine fig （Ficuscarica L., Moraceae） were used to research, including small green, big green, initial red, partial red, and full red, at about 15, 30, 65, 70 and 85 d after flower bud differentiation. A combination of electron microscopy and phloem-mobile symplasmic tracer carboxyfluorescein （CF）, the phloem unloading pathway was studied in the developmental fruit, meanwhile, fruit size and color, as well as soluble sugar and starch contents were also analasis. The growth of fig fruit follows a typical sigmoid growth curve with distinct three developmental stages： stage I, the first rapid growth phase; stage II, the lag phase; stage III, the second rapid growth phase, namely, turning and ripening stages; the transition from stage II to stage III represents the onset of ripening. During stage I and stage II, fruit soluble sugar contents is lower, while the onset of the fruit ripening, a rapid increase in both fruit volume and soluble sugar contents with main glucose and fructose was observed. The contents of starch were decreasing rapidly before the onset of ripening, then after, decreased slowly. Electron microscopy observations showed that the sieve element-companion cell （SE-CC） complex of the vascular bundles is apparently symplasmically connected through plasmodesmata with surrounding parenchyma cells （PCs） during the stage I and stage II, but a transition occurred from symplastic to apoplastic after the onset of the fruit ripening. Interestingly, an abundance of plasmodesmata was always observed between parenchyma cells during the fruit development. Imaging of carboxyfluorescein movement showed that the dye is released from the functional phloem strands before the onset of ripening, whereas the CF was confined to the phloem strands after the onset of ripening, considering that a transient and critical developmental checkpoint is present around the onset of ripen- ing about 1-2 days, and the apoplasmic unload

关 键 词：无花果 韧皮部卸载 超微结构 荧光示踪 共质体 质外体 

分 类 号：S663.3[农业科学—果树学]