Burrows Geoffrey E
School of Agricultural and Wine Sciences, Charles Sturt University, Locked Bag 588, Wagga Wagga, NSW 2678, Australia.
Plants (Basel). 2021 Nov 23;10(12):2551. doi: 10.3390/plants10122551.
Gymnosperms are generally regarded as poor resprouters, especially when compared to angiosperms and particularly following major disturbance. However, is it this clear-cut? This review investigates two main aspects of gymnosperm resprouting: (i) various papers have provided exceptions to the above generalization-how frequent are these exceptions and are there any taxonomic trends?; and (ii) assuming gymnosperms are poor resprouters are there any anatomical or physiological reasons why this is the case? Five of six non-coniferous gymnosperm genera and 24 of 80 conifer genera had at least one species with a well-developed resprouting capability. This was a wider range than would be expected from the usual observation 'gymnosperms are poor resprouters'. All conifer families had at least three resprouting genera, except the monospecific Sciadopityaceae. Apart from the aboveground stem, buds were also recorded arising from more specialised structures (e.g., lignotubers, tubers, burls and underground stems). In some larger genera it appeared that only a relatively small proportion of species were resprouters and often only when young. The poor resprouting performance of mature plants may stem from a high proportion of apparently 'blank' leaf axils. Axillary meristems have been recorded in a wide range of conifer species, but they often did not form an apical dome, leaf primordia or vascular connections. Buds or meristems that did form often abscised at an early stage. While this review has confirmed that conifers do not resprout to the same degree as angiosperms, it was found that a wide diversity of gymnosperm genera can recover vegetatively after substantial disturbance. Further structural studies are needed, especially of: (i) apparently blank leaf axils and the initial development of axillary meristems; (ii) specialised regeneration structures; and (iii) why high variability can occur in the resprouting capacity within species of a single genus and within genera of the same family.
裸子植物通常被认为是再生能力较差的植物，尤其是与被子植物相比，在遭受重大干扰后更是如此。然而，情况真的如此泾渭分明吗？这篇综述探讨了裸子植物再生的两个主要方面：（i）各种论文都提供了上述普遍观点的例外情况——这些例外有多频繁，是否存在分类学趋势？；（ii）假设裸子植物再生能力较差，那么导致这种情况的解剖学或生理学原因是什么？六个非针叶裸子植物属中的五个以及八十个针叶树属中的二十四个至少有一个物种具有发达的再生能力。这一范围比通常观察到的“裸子植物再生能力较差”所预期的要广。除了单种的日本金松科外，所有针叶树科至少有三个具有再生能力的属。除了地上茎外，还记录到芽从更特殊的结构（如木质块茎、块茎、树瘤和地下茎）中产生。在一些较大的属中，似乎只有相对较小比例的物种具有再生能力，而且通常只有在幼龄时才有。成熟植株再生能力差可能源于大量明显“空白”的叶腋。在多种针叶树物种中都记录到了腋生分生组织，但它们通常不形成顶端圆顶、叶原基或维管连接。形成的芽或分生组织往往在早期就脱落了。虽然这篇综述证实针叶树的再生程度不如被子植物，但发现许多裸子植物属在遭受重大干扰后能够通过营养繁殖恢复。还需要进一步的结构研究，特别是关于：（i）明显空白的叶腋以及腋生分生组织的初始发育；（ii）特殊的再生结构；（iii）为什么在同一属的物种内以及同一科的属内再生能力会出现高度变异性。
