Elleman C J, Franklin-Tong V, Dickinson H G
Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK.
School of Biological Sciences, University of Birmingham, Birmingham B15 2TT.
New Phytol. 1992 Jul;121(3):413-424. doi: 10.1111/j.1469-8137.1992.tb02941.x.
Interaction between the pollen grain, pollen tube and the stigma surface has been studied in five species regarded as possessing dry stigma surfaces; Brassica oleracea L., Arabidopsis thaliana (L.), Heynh, Papaver rhoeas L., Cosmos bipinnatus Cav. and Helianthus annuus L. In B. oleracea and A. thaliana, stigmatic response to pollination includes events in the papillar cytoplasm and changes to the stigmatic surface beneath the grain. In particular a specialized outer element of the cell wall expands prior to pollen tube penetration. The pollen tube, which enters through a 'foot' of pollen coating, grows in a space generated between an inner and the outer element of the wall and extends to the base of the papilla where it enters the middle lamellae of the subjacent cell layer. However, in A. thaliana tubes frequently were seen to penetrate all components of the stigmatic cell wall, an event only previously recorded in immature stigmas of B. oleracea. In self pollinations of self-incompatible B. oleracea involving strong S (incompatibility) alleles no changes take place in the papillar cell wall. In P. rhoeas the stigmatic surface responds to self and cross pollination by the secretion of electron-lucent material beneath the cuticle, causing it to become detached from the outer surface of the stigmatic cell wall. The pollen tubes then penetrate the cuticle and grow towards the base of the papilla in the space thus generated. The tubes continue to grow intercellularly in the transmitting tissue which lies horizontally in rays beneath the papillae. In members of the Compositae, C. bipinnatus and H. annuus, both stigma and pollen respond to pollination by producing copious quantities of an electron-opaque matrix, which frequently causes individual papillae to adhere together. Pollen tubes, which are formed following both compatible and incompatible intraspecific pollinations, grow into this matrix and toward the base of the papillae. There, in common with the other plants studied, they grow intercellularly and enter the transmitting tissue of the style. These findings are discussed in the light of current views of the mechanisms operating during angiosperm pollination and of the significance of the stigmatic response to the functioning of self-incompatibility mechanisms.
人们对被认为具有干燥柱头表面的五个物种的花粉粒、花粉管与柱头表面之间的相互作用进行了研究，这五个物种分别是：甘蓝（Brassica oleracea L.）、拟南芥（Arabidopsis thaliana (L.) Heynh）、虞美人（Papaver rhoeas L.）、波斯菊（Cosmos bipinnatus Cav.）和向日葵（Helianthus annuus L.）。在甘蓝和拟南芥中，柱头对授粉的反应包括乳头细胞质中的一系列事件以及花粉粒下方柱头表面的变化。特别是细胞壁的一种特殊外层成分在花粉管穿透之前会膨胀。花粉管通过花粉包被的“基部”进入，在细胞壁的内层和外层成分之间形成的空间中生长，并延伸到乳头基部，然后进入相邻细胞层的中层。然而，在拟南芥中，经常可以看到花粉管穿透柱头细胞壁的所有成分，这种情况以前只在甘蓝未成熟的柱头中记录过。在涉及强S（不亲和）等位基因的自交不亲和甘蓝的自花授粉中，乳头细胞壁没有变化。在虞美人中，柱头表面对自花授粉和异花授粉的反应是在角质层下方分泌电子透明物质，导致角质层与柱头细胞壁的外表面分离。然后花粉管穿透角质层，在由此产生的空间中朝着乳头基部生长。花粉管继续在位于乳头下方呈辐射状水平分布的传递组织中进行细胞间生长。在菊科植物波斯菊和向日葵中，柱头和花粉对授粉的反应是产生大量电子不透明基质，这常常导致单个乳头粘在一起。在种内亲和与不亲和授粉后形成的花粉管都生长到这种基质中，并朝着乳头基部生长。在那里，与其他研究的植物一样，它们进行细胞间生长并进入花柱的传递组织。根据目前关于被子植物授粉过程中作用机制的观点以及柱头反应对自交不亲和机制功能的重要性，对这些发现进行了讨论。
