Triterpenoids in aerenchymatous phellem contribute to internal root aeration and waterlogging adaptability in soybeans
Triterpenoids in aerenchymatous phellem contribute to internal root aeration and waterlogging adaptability in soybeans
复制标题
DOI：
10.1111/nph.18975
复制
发表时间：
2023-06-04
期刊：
影响因子：
9.4
通讯作者：
Nakazono，Mikio
中科院分区：
文献类型：
--
作者：
Takahashi，Hirokazu;Abo，Chisato;Nakazono，Mikio
大豆(Glycinmax)发育新分化的气孔韧皮部(AP)以响应内涝胁迫。AP在下胚轴和根中形成，因此有助于几种豆科植物的内部透气和对淹水的适应。在AP中已发现广泛积累的三萜类化合物--羽扇豆醇和白桦脂酸。然而，它们在植物中的生理作用仍不清楚。羽扇豆醇在羽扇豆醇合成酶(LUS)的作用下由2，3-氧化橙烯转化为白桦脂酸。值得注意的是，大豆有两个LUS基因(GmLUS1和GmLUS2)。功能分析揭示了三萜类化合物在AP中的生物学和生理功能。突变的AP细胞缺乏三萜积累和表皮层蜡质。羽扇豆醇和白桦酸是表皮层蜡质的主要成分，有助于组织疏水性和氧气向根的运输。突变体AP的组织孔隙度低于野生型，这导致通过AP向根的氧气运输减少。Ap中三萜类物质的积累有助于有效的内部曝气和根的发育，以适应湿害，这表明三萜类物质在提高耐涝能力方面具有重要意义。
Soybeans (Glycine max) develop newly differentiated aerenchymatous phellem (AP) in response to waterlogging stress. AP is formed in the hypocotyl and root, thus contributing to internal aeration and adaptation to waterlogging for several legumes. Extensive accumulation of triterpenoids – lupeol and betulinic acid – has been identified in AP. However, their physiological roles in plants remain unclarified. Lupeol is converted from 2,3‐oxidosqualene by lupeol synthase (LUS) and oxidized to betulinic acid. Notably, soybeans have twoLUSgenes (GmLUS1andGmLUS2).Functional analysis was performed to reveal the biological and physiological functions of triterpenoids in AP usinglusmutants.The AP cells oflus1mutant lacked triterpenoid accumulation and epicuticular wax. Lupeol and betulinic acid were the major components of epicuticular wax and contributed to tissue hydrophobicity and oxygen transport to the roots. Tissue porosity in AP was lower in thelus1mutant than in the wild‐type, which resulted in reduced oxygen transport to the roots via AP. This reduction in oxygen transport resulted in shallow root systems under waterlogged conditions.Triterpenoid accumulation in AP contributes to effective internal aeration and root development for adaptation to waterlogging, suggesting the significance of triterpenoids in improving waterlogging tolerance.