Assessment of O2 diffusivity across the barrier to radial O2 loss in adventitious roots of Hordeum marinum
Assessment of O2 diffusivity across the barrier to radial O2 loss in adventitious roots of Hordeum marinum
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DOI：
10.1111/j.1469-8137.2008.02467.x
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发表时间：
2008-01-01
期刊：
影响因子：
9.4
通讯作者：
Colmer, Timothy D.
中科院分区：
文献类型：
--
作者：
Garthwaite, Alaina J.;Armstrong, William;Colmer, Timothy D.
湿地植物根的亚根尖区域可以形成一道阻挡径向氧气损失(ROL)的屏障，但屏障阻力很少以其氧气扩散度来量化。在琼脂营养液中生长时，在100-120 mm长的根的基半部分上形成了对ROL的屏障。皮下细胞壁的自发荧光表明，假想的Suberin沉积与屏障表达是一致的。根部降温显示了屏障阻力中的一个重要的呼吸成分。通过调节地上部O~(-2)分压来消除呼吸效应，得到了5.96×10~(-7)cm~(-2)S(~(-1))的O~2扩散率，比顶端的O~(2-2)扩散率低96%，=1.59×10~(-5)cm(~(-2))S(~(-1))。结论是ROL屏障是两种成分协同作用的表现：一种是主要由外层次生细胞壁沉积引起的物理阻力；另一种是皮下/表皮层的呼吸活动，物理阻力是主要成分。
The subapical regions of wetland plant roots can develop a barrier to radial O-2 loss (ROL), but barrier resistance has rarely been quantified in terms of its O-2 diffusivity.Barrier resistance in adventitious roots of the waterlogging-tolerant Hordeum marinum was assessed from measurements of ROL using cylindrical platinum electrodes while either varying shoot O-2 partial pressures or cooling the rooting medium. Anatomical features were examined using fluorescence microscopy.When grown in stagnant agar nutrient solution, a barrier to ROL was induced over the basal half of 100-120-mm-long roots. Autofluorescence in hypodermal cell walls indicated that putative suberin deposition was coincident with barrier expression. Root cooling revealed a significant respiratory component in barrier resistance. Eliminating the respiration effect by manipulating shoot O-2 partial pressures revealed an O-2 diffusivity for the barrier of 5.96 x 10(-7) cm(2) s(-1), 96% less than that at the apex, which was >= 1.59 x 10(-5) cm(2) s(-1).It is concluded that the ROL barrier is a manifestation of two components acting synergistically: a physical resistance caused principally by secondary cell-wall deposits in the outer hypodermal layer; and respiratory activity in the hypodermal/epidermal layers; with physical resistance being the dominant component.