Wu Guo-Liang, Zhang Xiao-Yan, Zhang Ling-Yun, Pan Qiu-Hong, Shen Yuan-Yue, Zhang Da-Peng
College of Horticultural Science, Shanxi Agricultural University, 030801 Taigu, Shanxi, China.
Plant Cell Physiol. 2004 Oct;45(10):1461-70. doi: 10.1093/pcp/pch169.
The sieve element-companion cell (SE-CC) complex of the sepal bundles feeding the fleshy pericarp of developing walnut (Juglans regia L.) fruit is structurally symplasmically isolated, but the SE-CC complex of the minor ventral carpellary bundles located in the seed pericarp and feeding the seed is structurally symplasmically connected to its adjacent parenchyma cells. 14C-autoradiography indicated that the phloem of both the sepal and carpellary bundles was functional for unloading. Confocal laser scanning microscopy imaging of carboxyfluorescein unloading showed that the dye is confined to the phloem strands of the sepal bundles in the fleshy pericarp, but released from the phloem strands of the minor ventral carpellary bundles into the surrounding parenchyma cells in the seed pericarp. A 60-kDa acid invertase was immunolocalized to the cell wall of SE-CC complex and parenchyma cells in both the fleshy and seed pericarp. These data provide clear evidence for an apoplasmic phloem unloading pathway in the fleshy pericarp and a predominant symplasmic phloem unloading pathway parallel with a possible apoplasmic path as suggested by the presence of the extracellular invertase in the seed pericarp. A model of complex phloem unloading pathways in developing walnut fruit has been proposed.
为发育中的核桃（Juglans regia L.）果实肉质果皮提供养分的萼片束筛管分子-伴胞（SE-CC）复合体在结构上是共质体隔离的，但位于种子果皮并为种子提供养分的腹侧心皮小束的SE-CC复合体在结构上与相邻的薄壁细胞共质体相连。14C-放射自显影表明，萼片束和心皮束的韧皮部都具有卸载功能。羧基荧光素卸载的共聚焦激光扫描显微镜成像显示，染料局限于肉质果皮中萼片束的韧皮部束，但从小腹侧心皮束的韧皮部束释放到种子果皮中的周围薄壁细胞中。一种60 kDa的酸性转化酶被免疫定位到肉质果皮和种子果皮中SE-CC复合体和薄壁细胞的细胞壁上。这些数据为肉质果皮中的质外体韧皮部卸载途径以及种子果皮中存在细胞外转化酶所暗示的与可能的质外体途径平行的主要共质体韧皮部卸载途径提供了明确证据。提出了发育中的核桃果实复杂韧皮部卸载途径的模型。
