A sucrose supply from the leaves is required for aerenchymatous phellem formation in the hypocotyl of soybean under waterlogged conditions.
A sucrose supply from the leaves is required for aerenchymatous phellem formation in the hypocotyl of soybean under waterlogged conditions.
复制标题
在淹水条件下，大豆下胚轴中通气细胞的木栓形成需要来自叶子的蔗糖供应。
DOI：
10.1093/aob/mcx205
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发表时间：
2018
期刊：
影响因子：
4.2
通讯作者：
Mikio Nakazono
中科院分区：
文献类型：
--
作者：
Hirokazu Takahashi;Qi Xiaohua;Satoshi Shimamura;Asako Yanagawa;Susumu Hiraga;Mikio Nakazono
背景与目的土壤内涝常导致植物根系缺氧，严重抑制植物生长。通气性组织的形成--相互连接的空间，促进气体在植物空中和水下部分之间和内部的移动--是应对内涝条件的一种适应性特征。大豆形成气孔次生组织，称为气孔韧皮部(AP)，来源于韧皮部最外层的细胞层。为了了解水分以外的其他因素对韧皮部和韧皮部形成的影响，我们研究了黑暗、CO2缺乏和韧皮部运输受阻对大豆幼苗韧皮部和韧皮部形成的影响。方法用下胚轴横截面面积比表示气生韧皮部和韧皮部形成。通过使用氧化钙和氢氧化钠来消耗二氧化碳。下胚轴受热环剥，韧皮部运输受阻。关键结果在光照条件下，淹水诱导下胚轴中高浓度蔗糖的积累，随后在下胚轴中形成木栓层和AP。Phellogen和AP的形成受到黑暗、CO2缺乏和韧皮部运输受阻的抑制。切断上胚轴上方的枝条也能抑制果胶和果胶的形成，但在切面施加蔗糖(但不是葡萄糖或果糖)后，果胶和果胶的形成得以恢复。结论在淹水土壤条件下，来自叶片的蔗糖是大豆下胚轴形成果胶和果胶的必要条件。因此，维持较高的蔗糖浓度对于木脂素和AP的发育以及木脂素向AP的分化是必不可少的。
Background and AimsSoil waterlogging often causes oxygen deficiency in the root systems of plants and severely inhibits plant growth. Formation of aerenchyma – interconnected spaces that facilitate the movement of gases between and within the aerial and submerged parts of plants – is an adaptive trait for coping with waterlogged conditions. Soybean (Glycine max) forms porous secondary tissues known as aerenchymatous phellem (AP), which are derived from the outermost cell layer of phellogen. To understand what factors other than waterlogging are involved in phellogen and AP formation, we examined how their formation in soybean seedlings was affected by darkness, CO2deficiency and blockage of phloem transport.MethodsAerenchymatous phellem and phellogen formation were expressed as area ratios in cross-sections of hypocotyl. CO2was depleted by use of calcium oxide and sodium hydroxide. Phloem transport was blocked by heat-girdling of hypocotyls. Sucrose levels were measured by spectrophotometry.Key ResultsUnder light conditions, waterlogging induced the accumulation of high concentrations of sucrose in hypocotyls, followed by phellogen and AP formation in hypocotyls. Phellogen formation and AP formation were inhibited by darkness, CO2deficiency and blockage of phloem transport. Phellogen formation and AP formation were also inhibited by excision of shoots above the epicotyl, but they recovered following application of sucrose (but not glucose or fructose application) to the cut surface.ConclusionsThe results demonstrate that sucrose derived from leaves is essential for AP and phellogen formation in soybean hypocotyls under waterlogged soil conditions. Maintenance of a high sucrose concentration is thus essential for the development of phellogen and AP and the differentiation of phellogen to AP.