Abstract:Background: Interpretation of the floral structure of Zingiberaceae has long concentrated on the relationships of the androecial members. It suggested that labellum is composed of two structures rather than three or five, and glands are interpreted either as gynoecial part or as androecial members. Methods: Serial sections were used to observe the vasculature of normal and two-staminate flowers in Alpinia intermedia 'shengzhen'. Floral diagrams were drawn to interpret the morphological category of the floral o… Show more
“…In Zingiberales, abnormal flowers provide material evidence to study the homeosis through comparative anatomical analyses. Compared with organs in other whorls, androecial members show a much wider variation in abnormal flowers, which conforms to the androecial modifications seen in this order (Rao 1963; Maas 1977; Song et al 2003; Li et al 2020). In this research, comparisons between the abnormal flowers and the normal flowers clearly indicated homologies between the androecial members.…”
Canna indica is a common ornamental plant with asymmetric flowers having colourful petaloid staminodes. The only fertile stamen comprises a one‐theca anther and a petaloid appendage and represents the lowest stamen number in the order Zingiberales. The molecular mechanism for the asymmetric androecial petaloidy remains poorly understood. Here, we studied the identity specification in Canna stamen.
We observed four types of abnormal flower in terms of androecium identity transformation and analysed the corresponding floral symmetry changes. We further tested the expression patterns of B‐ and C‐class MADS‐box genes using in situ hybridization in normal Canna stamen.
Homeotic conversions in the androecium were accompanied by floral symmetry changes, and the asymmetric stamen is key in contributing to the floral asymmetry. Both B‐ and C‐class genes exhibited higher expression levels in the anther primordium than in other androecial parts. This asymmetric expression pattern precisely corresponded to the asymmetric identities of the Canna androecium.
We identified C. indica as a model species for studying androecial organ identity and floral symmetry synthetically in Zingiberales. We hypothesized that homeotic genes specify floral organ identity in a putative dose‐dependent manner. The results add to the current understanding of organ identity‐related floral symmetry.
“…In Zingiberales, abnormal flowers provide material evidence to study the homeosis through comparative anatomical analyses. Compared with organs in other whorls, androecial members show a much wider variation in abnormal flowers, which conforms to the androecial modifications seen in this order (Rao 1963; Maas 1977; Song et al 2003; Li et al 2020). In this research, comparisons between the abnormal flowers and the normal flowers clearly indicated homologies between the androecial members.…”
Canna indica is a common ornamental plant with asymmetric flowers having colourful petaloid staminodes. The only fertile stamen comprises a one‐theca anther and a petaloid appendage and represents the lowest stamen number in the order Zingiberales. The molecular mechanism for the asymmetric androecial petaloidy remains poorly understood. Here, we studied the identity specification in Canna stamen.
We observed four types of abnormal flower in terms of androecium identity transformation and analysed the corresponding floral symmetry changes. We further tested the expression patterns of B‐ and C‐class MADS‐box genes using in situ hybridization in normal Canna stamen.
Homeotic conversions in the androecium were accompanied by floral symmetry changes, and the asymmetric stamen is key in contributing to the floral asymmetry. Both B‐ and C‐class genes exhibited higher expression levels in the anther primordium than in other androecial parts. This asymmetric expression pattern precisely corresponded to the asymmetric identities of the Canna androecium.
We identified C. indica as a model species for studying androecial organ identity and floral symmetry synthetically in Zingiberales. We hypothesized that homeotic genes specify floral organ identity in a putative dose‐dependent manner. The results add to the current understanding of organ identity‐related floral symmetry.
“…Song et al [ 41 ] described six types of abnormal flowers in Alpinia ; these abnormalities include flowers with 2 fertile stamens, 1.5 stamens, 1 stamen, single stamen with only one theca (½ stamen), and fertile stamen completely absent as well as the occurrence of twin flowers forming mirror images. Li et al [ 42 ] recently reported two-staminate aberrant flowers in a cultivar A. intermedia ‘shengzhen’. These aberrant flowers share with one another alterations in the form of the androecial members that indicate common deviations from a canalized developmental pathway.…”
Floral symmetry studies often focus on the development of monosymmetric and polysymmetric flowers, whereas asymmetric flowers and their position and function within the inflorescence structure are largely neglected. Cannaceae is one of the few families that possesses truly asymmetric flowers, serving as a model to study the characters and mechanisms involved in the development of floral asymmetry and its context within the developing and mature inflorescence. In this study, inflorescence structure and floral morphology of normal asymmetric flowers and 16 aberrant flower collections from Canna indica L. and C. glauca L. were photographed, analyzed, and compared with attention to stamen petaloidy, floral symmetry, and inflorescence branching patterns anterior and posterior to the aberrant flower. In comparison with normal flowers, the aberrant flowers are arranged into abnormal partial florescences, and vary in floral symmetry, orientation, and degree of androecial petaloidy. The appendage of the fertile stamen is universally located distal from the higher order bract, indicating an underlying influence of inflorescence architecture. A synthetic model is proposed to explain the relationship between floral symmetry and inflorescence structure. Data from the observation of aberrant phenotypes strongly support the hypothesis that irregular petaloidy of the stamens is correlated with an asymmetric morphogenetic field within the inflorescence that contributes to the overall floral asymmetry in Canna flowers.
“…Controlling the flowering time and understanding the physiological mechanism of the induction of flowers are essential to the tourism, research, and flower industries [1]. In recent years, many researchers have studied the flowering process, including flower morphological structure, nutrients, mineral elements, enzymes, and relevant genes in flowers, so as to reveal the biological characteristics and regulate the flowering period of different plants [2][3][4][5]. Based on the study of flower morphology in the genus Capsella, Neuffer and Paetsch [6] specifically disclosed the petal size, pollen number, stigma length, and so on in Capsella grandiflora, C. rubella, and C. bursa-pastoris.…”
Styrax japonicus is a small ornamental tree with medicinal values, although its flowering period is short. To date, information about the morphological and physiological characteristics of the petals during the flowering period is limited. In this study, we observed the structure of the petals at the full flowering stage with a scanning electron microscope and detected the contents of nutrients, minerals, and endogenous hormones and the activities of enzymes at different flowering stages. The results showed that the content of soluble sugar exhibited an ‘increase-decrease’ trend, whereas the contents of soluble protein, nitrogen (N), phosphorus (P), and abscisic acid (ABA) showed a ‘decrease-increase’ pattern. The content of starch descended continuously, but the contents of potassium (K), gibberellic acid (GA3), indoleacetic acid (IAA), and malondialdehyde (MDA) ascended continuously. The activities of peroxidase (POD) and superoxide dismutase (SOD) first rose and then declined during the flowering period. Higher contents of soluble sugar, N, K, and IAA promoted S. japonicus flowering; meanwhile, lower contents of starch, soluble protein, P, and GA3 in addition to the lower activity of SOD might be some of the causes of the short flowering period. This work will serve as the foundation for a scientific technique to utilize the flowers and extend the flowering period in S. japonicus.
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