INTRODUCTIONIn this protocol, we describe methods for cultivating Antirrhinum (snapdragon) species. These plants are easily grown, provided that they have sufficient light and are not overwatered. In good conditions, most species will flower and produce seeds within 3-4 mo. Strongly growing plants should suffer from few pests or diseases, but we also prescribe methods for dealing with microbes and insects that commonly damage Antirrhinum.
INTRODUCTIONThis protocol describes general strategies for propagating Antirrhinum (snapdragon) species: self- and cross-pollination, cuttings, and grafting. Antirrhinum majus cultivars and some wild species are self-fertile, but they require self-pollination for high seed yields. Although self-fertile, A. majus shows unilateral incompatibility and can only be crossed to other self-incompatible species as the female parent. All Antirrhinum species can be propagated clonally from cuttings. Antirrhinum also readily forms grafts within and between species.
Heteroblasty refers to the changes in leaf shape and size (allometry) along stems. Although evolutionary changes involving heteroblasty might contribute to leaf diversity, little is known of the extent to which heteroblasty differs between species or how it might relate to other aspects of allometry or other developmental transitions. Here, we develop a computational model that can quantify differences in leaf allometry between Antirrhinum (snapdragon) species, including variation in heteroblasty. It allows the underlying genes to be mapped in inter-species hybrids, and their effects to be studied in similar genetic backgrounds. Heteroblasty correlates with overall variation in leaf allometry, so species with smaller, rounder leaves produce their largest leaves earlier in development. This involves genes that affect both characters together and is exaggerated by additional genes with multiplicative effects on leaf size. A further heteroblasty gene also alters leaf spacing, but none affect other developmental transitions, including flowering. We suggest that differences in heteroblasty have co-evolved with overall leaf shape and size in Antirrhinum because these characters are constrained by common underlying genes. By contrast, heteroblasty is not correlated with other developmental transitions, with the exception of internode length, suggesting independent genetic control and evolution.
INTRODUCTIONThe Antirrhinum species group comprises approximately 20 morphologically diverse members that are able to form fertile hybrids. It includes the cultivated snapdragon Antirrhinum majus, which has been used as a model for biochemical and developmental genetics for more than 75 yr. The research infrastructure for A. majus, together with the interfertility of the species group, allows Antirrhinum to be used to examine the genetic basis for plant diversity.
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