Sucrose transport-related genes are expressed in both maternal and filial tissues of developing wheat grains
Sucrose transport-related genes are expressed in both maternal and filial tissues of developing wheat grains
复制标题
DOI：
10.1071/pp00012
复制
发表时间：
2000-01-01
期刊：
影响因子：
--
通讯作者：
Patrick, JW
中科院分区：
文献类型：
--
作者：
Bagnall, N;Wang, XD;Patrick, JW
小麦（Triticum turgidum var. durum cv.）韧皮部进口的光同化物（蔗糖）的筛后元素运输包括在同质分离的母体和子代组织之间进出籽粒质的膜运输。探讨了籽粒快速灌浆过程中这些膜转运步骤的细胞定位和机制。基因组南方分析表明存在一个多基因的蔗糖/H+同调体家族。一个或多个SUTs在发育中的谷物中高度表达，p型H+/ atp酶(s)和蔗糖结合蛋白（SBP）也是如此。这些基因的转录本在维管薄壁细胞、珠心突起细胞和糊粉细胞中检测到。针对SUT、H+/ atp酶和SBP的抗体被选择性地结合到血管薄壁细胞、核心投射转移细胞和修饰糊粉/亚糊粉转移细胞的质膜上。核状投射转移细胞和改性糊粉/亚糊粉转移细胞表现出较强的质子泵送活性。相比之下，SUT转运功能仅限于含有改性糊粉/亚糊粉转运细胞的子代组织。基于这些发现，我们得出结论，在母体组织中表达的SUTs不具有蔗糖/H+同调体的功能。从珠心投射转移细胞到胚乳腔的膜交换是通过一个尚未确定的机制发生的。蔗糖从胚乳腔进入子代组织的摄取是由定位于修饰糊粉/亚糊粉转移细胞质膜上的SUT介导的。
In developing wheat grains (Triticum turgidum var. durum cv. Fransawi), post-sieve element transport of phloem-imported photoassimilates (sucrose) includes membrane transport, to and from the grain apoplasm, between symplasmically-isolated maternal and filial tissues. The cellular location and mechanism of these membrane transport steps were explored during rapid grain fill. Genomic Southern analysis indicated the presence of a multigene family of sucrose/H+ symporters (SUTs). One or more SUTs were highly expressed in developing grains, as were P-type H+/ATPase(s) and a sucrose binding protein (SBP). Transcripts of these genes were detected in vascular parenchyma, nucellar projection and aleurone cells. Antibodies, raised against a SUT, an H+/ATPase and a SBP, were selectively bound to plasma membranes of vascular parenchyma cells, nucellar projection transfer cells and modified aleurone/sub-aleurone transfer cells. The nucellar projection transfer cells and modified aleurone/sub-aleurone transfer cells exhibited strong proton pumping activity. In contrast, SUT transport function was restricted to filial tissues containing modified aleurone/sub-aleurone transfer cells. Based on these findings, we conclude that SUTs expressed in maternal tissues do not function as sucrose/H+ symporters. Membrane exchange from nucellar projection transfer cells to the endosperm cavity occurs by an as yet unresolved mechanism. Sucrose uptake from the endosperm cavity into filial tissues is mediated by a SUT localised to plasma membranes of the modified aleurone/sub-aleurone transfer cells.