Key message

Endogenous ROS, including those produced by NADPH oxidase, are required for spruce pollen germination and regulate membrane potential in pollen tubes; \({\mathbf{O}}_{{\mathbf{2}}}^{{{\mathbf{ \cdot - }}}}\) and H ₂ O ₂ are unevenly distributed along the tube.

Abstract

Recently, the key role of reactive oxygen species (ROS) in plant reproduction has been decisively demonstrated for angiosperms. This paper is dedicated to the involvement of ROS in pollen germination of gymnosperms, which remained largely unknown. We found that ROS are secreted from pollen grains of blue spruce during the early stage of activation. The localization of different ROS in pollen tube initials and pollen tubes demonstrated the accumulation of H₂O₂ in pollen tube apex. Colocalization with mitochondria-derived \({\text{O}}_{2}^{ \cdot - }\) showed that H₂O₂ is produced in mitochondria and amyloplasts in addition to its apical gradient in the cytosol. The necessity of intracellular ROS and, particularly, \({\text{O}}_{2}^{ \cdot - }\) for pollen germination was demonstrated using different antioxidants. ·OH and extracellular ROS, on the contrary, were found to be not necessary for germination. Exogenous hydrogen peroxide did not affect the germination efficiency but accelerated pollen tube growth in a concentration-dependent manner. The optical measurements of membrane potential showed that in spruce pollen tubes there is a gradient which is controlled by H⁺-ATPase, potassium- and calcium-permeable channels, anion channels and ROS, as demonstrated by inhibitory analysis. An important role of NADPH oxidase in the regulation of ROS balance in particular, and in germination in general, has been demonstrated by inhibiting the enzyme, which leads to the reduction in ROS release, depolarization of pollen tube plasma membrane, and blocking of pollen germination.

中文翻译：

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活性氧在青海云杉花粉萌发中的作用。

关键信息

云杉花粉萌发和调节花粉管中膜电位需要内源性ROS，包括NADPH氧化酶产生的ROS。 \（{{mathbf {O}} _ {{\ mathbf {2}}} ^ {{{\ mathbf {\ cdot-}}}} \} 和H ₂ O ₂沿管不均匀分布。

抽象

最近，对于被子植物而言，活性氧（ROS）在植物繁殖中的关键作用已得到决定性的证明。本文致力于ROS参与裸子植物花粉萌发的研究，目前尚不清楚。我们发现在激活的早期，ROS是从蓝色云杉的花粉粒中分泌的。花粉管头和花粉管中不同ROS的定位表明，H ₂ O ₂在花粉管顶端积累。与线粒体派生的\（{\ text {O}} _ {2} ^ {\ cdot-} \的共定位显示H ₂ O ₂除了其在细胞质中的顶端梯度外，它还由线粒体和淀粉质体产生。使用不同的抗氧化剂证明了花粉萌发的细胞内ROS的必要性，尤其是\（{\ text {O}} _ {2} ^ {\ cdot-} \）。相反，发现·OH和细胞外ROS对发芽不是必需的。外源过氧化氢不影响发芽效率，但以浓度依赖的方式加速花粉管的生长。膜电位的光学测量表明，在云杉花粉管中存在一个由H ⁺控制的梯度。-ATPase，钾离子和钙离子可渗透通道，阴离子通道和ROS，如抑制分析所示。通过抑制NADPH氧化酶，特别是在ROS平衡的调节中以及在发芽​​中，发挥了重要作用，这种酶可导致ROS释放减少，花粉管质膜去极化和阻止花粉萌发。 。