CaJOINTLESS is a MADS-box gene involved in suppression of vegetative growth in all shoot meristems in pepper

In aiming to decipher the genetic control of shoot architecture in pepper (Capsicum spp.), the allelic late-flowering mutants E-252 and E-2537 were identified. These mutants exhibit multiple pleiotropic effects on the organization of the sympodial shoot. Genetic mapping and sequence analysis indicated that the mutants are disrupted at CaJOINTLESS, the orthologue of the MADS-box genes JOINTLESS and SVP in tomato and Arabidopsis, respectively. Late flowering of the primary and sympodial shoots of Cajointless indicates that the gene functions as a suppressor of vegetative growth in all shoot meristems. While CaJOINTLESS and JOINTLESS have partially conserved functions, the effect on flowering time and on sympodial development in pepper, as well as the epistasis over FASCICULATE, the homologue of the major determinant of sympodial development SELF-PRUNING, is stronger than in tomato. Furthermore, the solitary terminal flower of pepper is converted into a structure composed of flowers and leaves in the mutant lines. This conversion supports the hypothesis that the solitary flowers of pepper have a cryptic inflorescence identity that is suppressed by CaJOINTLESS. Formation of solitary flowers in wild-type pepper is suggested to result from precocious maturation of the inflorescence meristem.     

Genetic interactions in the control of flowering time and reproductive structure development in tomato (Solanum lycopersicum)

Different tomato (Solanum lycopersicum) mutants, affected in flowering time, reproductive structure or plant architecture, were crossed to produce double mutants in order to investigate gene interactions in flowering regulation in this autonomous species with a sympodial growth habit. The compound inflorescence: uniflora, uniflora: self pruning, uniflora: blind, and jointless: uniflora double mutants all produced solitary flowers like their uniflora parent, instead of inflorescences. All double mutants were late flowering. uniflora: blind and uniflora: self pruning had flowering times intermediate between those of their two parents. jointless: uniflora and compound inflorescence: uniflora flowered later than uniflora, the mutant with the most delayed flowering. All double mutants developed strong lateral shoots at node levels approximately corresponding to the level at which their parent cultivars initiated their first reproductive structure, which is a typical trait of uniflora. These results suggest that the UNIFLORA gene acts upstream of the other investigated genes in controlling flowering in tomato, and that floral transition of the primary shoot and floral transition of sympodial segments are regulated differently.     

Unisexual flowers as a robust synapomorphy in Cariceae (Cyperaceae)? Evidence for bisexual flowers in Schoenoxiphium

Cariceae, the largest tribe within Cyperaceae, comprises about 2000 species in five genera. Cariceae is usually considered to be distinct from other Cyperaceae by the presence of exclusively unisexual flowers and by the arrangement of the pistillate flowers in single-flowered spikelets that are enclosed by the flask-like spikelet prophyll (utricle or perigynium). The nature of several morphological features of the Cariceae inflorescence remains controversial. The staminate reproductive units, as well as earlier reported bisexual reproductive units in Schoenoxiphium have been considered to be reduced partial inflorescences, or flowers. Aims of this study are to test both interpretations, based on a floral ontogenetic investigation. Moreover, for the first time, detailed SEM micrographs are presented of the inflorescence and floral development and of bisexual flowers in Schoenoxiphium. We propose that ‘inhibition of bisexuality’ is a more robust synapomorphy in Cariceae than ‘presence of only unisexual flowers’.     

Sex expression as affected by N6-benzylaminopurine in staminate inflorescence of Luffa cylindrica

The effect of N⁶-benzylaminopurine (BA) on the sex expressionof staminate inflorescences of Luffa cylindrica was investigated.Direct application of BA to the staminate inflorescence inducedbisexual and pistillate flowers and finally caused the inflorescenceto develop into a shoot that was similar to the main shoot.Such modification in a staminate inflorescence from the proximalto the distal nodes is usually in the order of staminate flowers,bisexual flowers, pistillate flowers and foliage leaves (shoot).Pinching of the main stem also caused the inflorescence to developinto a shoot in the absence of lateral shoots. BA-induced femalenesswas strengthened when the number of leaves remaining on theplant was increased. On the other hand, application of BA tothe shoot apex of the main stem starting at the 2-leaf stagesuppressed differentiation of the flower bud on the main stem. (Received December 22, 1979; )     

Homeosis in Araceae Flowers: The Case of Philodendron melinonii

The early stages of development of the inflorescence of Philodendronmelinonii were examined using scanning electron microscopy.Pistillate flowers are initiated on the lower portion of theinflorescence and staminate flowers are initiated on the distalportion. The male flowers have four to five stamens. The femaleflowers have a multilocular ovary consisting of four to sixlocules. A transition zone consisting of sterile male flowersand bisexual flowers with fused or free carpels and staminodesis also present on the inflorescences. This zone is locatedbetween the male and female flower zones. Generally, the portionof the bisexual flower facing the male zone forms stamens, andthe portion facing the female zone develops an incomplete gynoeciumwith few carpels. In P. melinonii, the incomplete separationof staminodes from the gynoecial portion of the whorl showsthat the staminodes and carpels belong to the same whorl. Thebisexual flowers of P. melinonii are believed to be a case ofhomeosis where carpels have been replaced by sterile stamenson the same whorl. At the level of the inflorescence, pistillateand staminate flowers are inserted on the same contact parastichiesalong the inflorescence; there is no discontinuity between thefemale zone, the bisexual zone, and the male zone. The presenceof bisexual flowers is believed to correspond to a morphogeneticgradient at the level of the inflorescence as a whole. Copyright2000 Annals of Botany Company Flower, development, gradient, inflorescence     

Observations of inflorescence patterns and flower sex in a population of Sagittaria papillosa Buch. (Alismataceae)

Sagittaria papillosa Buch. is monoecious with unisexual flowers, pistillate below, staminate above, typically with an unbranched scape. A large population with unusual numbers of staminate and bisexual flowers on the lowest whorl of the inflorescence and many particles was quantitatively evaluated. First-formed inflorescences had more staminate and bisexual flowers than those produced later. Branched scapes were predominantly found to be the second inflorescence produced by a given plant. Genetic crosses between flowers on recemes and panicles produced no branched inflorescences. When grown under greenhouse conditions all tested plants had racemes with pistillate flowers in the lower whorls and staminate ones above. Data from soil parameters, daylengths and air temperatures are compared to reported information on modification of flower sexuality by these factors.     

PATTERNS OF STAMEN VASCULATURE IN THE ARACEAE

A survey of the three-dimensional organization of stamen vasculature in 100 genera and over 350 species of Araceae was made using clearings. The Araceae exhibit highly varied stamen vasculature, with three main patterns: 1) vascular bundles unbranched, 1–3 per stamen, 2) forked bundles in some or all stamens, 3) anastomosing vascular systems with several to many bundles entering a single stamen. Three major groups of taxa in the family can be recognized on the basis of their predominant pattern of stamen vasculature. Virtually all genera with bisexual flowers (most Pothoideae, Monsteroideae, Calloideae, Lasieae) have unbranched bundles, one per stamen, except two to three in some species of Holochlamys, Spathiphyllum, and Scindapsus. Forked stamen bundles are virtually restricted to and occur nearly throughout the monoecious Lasioideae, Philodendroideae, Colocasioideae and among certain Aroideae (sensu Engler), including tribes Arophyteae, Spathicarpeae (Asterostigmateae) and Protareae. No forked bundles were found in tribe Areae (Aroideae), except Theriophonum indicum or any Araceae with bisexual flowers, except two species of Cyrtosperma. Anastomosing systems are virtually limited to members of tribe Areae with larger stamens, such as Arum, Helicodiceros, Eminium and Dracunculus species. A similar pattern occurs in some Amorphophallus, but other patterns occur as well. The distributions of forked bundles and anastomosing systems in the family are notable because they are both highly congruent with Philodendroideae-Colocasioideae, and Aroideae, respectively, in Grayum's new system for the family. Virtually all of the genera with forked bundles are grouped together in the Philodendroideae-Colocasioideae. All of the genera with anastomosing systems are in the Areae, including the complex and variable Amorphophallus, which has an uncertain systematic placement.     

SYMMETRY AND DEVELOPMENT OF BUTOMUS UMBELLATUS (BUTOMACEAE) AND LIMNOCHARIS FLAVA (LIMNOCHARITACEAE)

The prostrate rhizome of Butomus umbellatus produces branch primordia of two sorts, inflorescence primordia and nonprecocious vegetative lateral buds. The inflorescence primordia form precociously by the bifurcation of the apical meristem of the rhizome, whereas the non-precocious vegetative buds are formed away from the apical meristem. The rhizome normally produces a branch in the axial of each foliage leaf. However, it is unclear whether the rhizome is a monopodial or a sympodial structure. Lateral buds are produced on the inflorescence of B. umbellatus either by the bifurcation or trifurcation of apical meristems. The inflorescence consists of monochasial units as well as units of greater complexity, and certain of the flower buds lack subtending bracts. The upright vegetative axis of Limnocharis flava has sympodial growth and produces evicted branch primordia solely by meristematic bifurcation. Only certain leaves of the axis are associated with evicted branch primordia and each such primordium gives rise to an inflorescence. The flowers of L. flava are borne in a cincinnus and, although the inflorescence is simpler than that of Butomus umbellatus, the two inflorescences appear to conform to a fundamental body plan. The ultimate bud on the inflorescence of Limnocharis flava always forms a vegetative shoot, and the inflorescence may also produce supernumerary vegetative buds. Butomus umbellatus and Limnocharis flava exhibit a high degree of mirror image symmetry.     

Correlation between development of female flower buds and expression of the CS-ACS2 gene in cucumber plants

Ethylene plays a key role in sex determination of cucumber flowers. Gynoecious cucumber shoots produce more ethylene than monoecious shoots. Because monoecious cucumbers produce both male and female flower buds in the shoot apex and because the relative proportions of male and female flowers vary due to growing conditions, the question arises as to whether the regulation of ethylene biosynthesis in each flower bud determines the sex of the flower. Therefore, the expression of a 1-aminocyclopropane-1-carboxylic acid synthase gene, CS-ACS2, was examined in cucumber flower buds at different stages of development. The results revealed that CS-ACS2 mRNA began to accumulate just beneath the pistil primordia of flower buds at the bisexual stage, but was not detected prior to the formation of the pistil primordia. In buds determined to develop as female flowers, CS-ACS2 mRNA continued to accumulate in the central region of the developing ovary where ovules and placenta form. In gynoecious cucumber plants that produce only female flowers, accumulation of CS-ACS2 mRNA was detected in all flower buds at the bisexual stage and at later developmental stages. In monoecious cucumber, flower buds situated on some nodes accumulated CS-ACS2 mRNA, but others did not. The proportion of male and female flowers in monoecious cucumbers varied depending on the growth conditions, but was correlated with changes in accumulation of CS-ACS2 mRNA in flower buds. These results demonstrate that CS-ACS2-mediated biosynthesis of ethylene in individual flower buds is associated with the differentiation and development of female flowers.     

Sex expression in fruiting male vines of kiwifruit

Summary In three canes on each of five fruiting male kiwifruit vines (A. deliciosa var. deliciosa (A. Chev) Liang and Ferguson), staminate and bisexual flowers were interspersed, so that staminate, bisexual and mixed inflorescences were found. Further variation in inflorescence composition resulted from the abortion of flower buds prior to anthesis. These two sources of variation, in combination, resulted in 19 inflorescence patterns, which varied substantially in frequency among and within vines. Some tendencies were determined. In particular, most of the inflorescences had retained their terminal flower, whereas just over half had retained one or both primary lateral flowers, and in two-thirds of the inflorescences retaining a terminal flower, this was bisexual. The five vines ranged in bisexual flower frequency from 40% to 70%. Phenotypic Gender (P) estimates are given for each vine, based on the frequencies of staminate and bisexual flowers from three canes per vine. Flower development, lability in sex expression and the use of P estimates as part of a selection index in breeding for hermaphrodite kiwifruit cultivars are discussed.     

赤霉素诱导小桐子产生两性花

小桐子（Jatropha curcas）种子含油率高,油脂组成适合于生产生物燃油,是制备航空生物燃油和生物柴油的理想原料。小桐子是一种雌雄同株植物,雌雄花着生于同一花序,其花序中雌花比例很低,可能是其种子产量低的主要原因之一。本文研究用不同浓度的赤霉素外源喷施处理小桐子花序芽对其花和种子发育的影响。结果表明：外源赤霉素处理能够诱导小桐子产生两性花,且处理浓度越高,两性花数量越多;随着两性花数量的增加,雌花数量相应越少,但雌花与两性花数量之和在各处理和对照之间差异不显著,这表明赤霉素诱导出的两性花可能来源于雌花。另外,高浓度(500~1500mg·L-1)的赤霉素处理会导致小桐子的种子不能正常发育, 表现为每个果实中的种子数量、大小、单粒种子重量、每个果序的种子重量以及种子的含油量都显著减少。这些结果有助于深入理解赤霉素在小桐子花器官形成及种子发育过程中所发挥的生理作用,为从分子水平上对小桐子进行遗传改良、提高其种子产量奠定基础。     

Retardation of inflorescence development inCalendula officinalis by a morphactin and its application

The morphactin - chlorflurenol at 1, 5, 25, 125 and 625 μg/plant either caused total damage of the shoot apices or allowed a few inflorescences to develop with few or no flowers. The inflorescences arising in the lateral branches showed suppressed bracts and modified flowers. With time the treated plants recovered and showed a significant increase in the growth of laterals and the number of inflorescences. Thus morphactin can be used for prolonging the growth period and for obtaining more wholesome plants.     

Benzyladenine Treatment Significantly Increases the Seed Yield of the Biofuel Plant Jatropha curcas

Jatropha curcas, a monoecious perennial biofuel shrub belonging to the family Euphorbiaceae, has few female flowers, which is one of the most important reasons for its poor seed yield. This study was undertaken to determine the effects of the plant growth regulator 6-benzyladenine (BA) on floral development and floral sex determination of J. curcas. Exogenous application of BA significantly increased the total number of flowers per inflorescence, reaching a 3.6-fold increase (from 215 to 784) at 160 mg/l of BA. Furthermore, BA treatments induced bisexual flowers, which were not found in control inflorescences, and a substantial increase in the female-to-male flower ratio. Consequently, a 4.5-fold increase in fruit number and a 3.3-fold increase in final seed yield were observed in inflorescences treated with 160 mg/L of BA, which resulted from the greater number of female flowers and the newly induced bisexual flowers in BA-treated inflorescences. This study indicates that the seed yield of J. curcas can be increased by manipulation of floral development and floral sex expression.     

Modeling Nymphoides architecture: A morphological analysis of Nymphoides aquatica (Menyanthaceae)

? Premise of the study: Species in the aquatic genus Nymphoides have inflorescences that appear to arise from the petioles of floating leaves. The inflorescence-floating leaf complex can produce vegetative propagules and/or additional inflorescences and leaves. We analyzed the morphology of N. aquatica to determine how this complex relates to whole plant architecture and whether whole plant growth is sympodial or monopodial. ? Methods: We used dissections, measurements, and microscopic observations of field-collected plants and plants cultivated for 2 years in outdoor tanks in south Florida, USA. ? Key results: Nymphoides aquatica had a submerged plagiotropic rhizome that produced floating leaves in an alternate/spiral phyllotaxy. Rhizomes were composed of successive sympodial units that varied in the number of leaves produced before the apex terminated. The basic sympodial unit had a prophyll that subtended a renewal-shoot bud, a short-petioled leaf (SPL) with floating lamina, and an inflorescence; the SPL axillary bud expanded as a vegetative propagule. Plants produced either successive basic sympodial units or expanded sympodia that intercalated long-petioled leaves between the prophyll and the SPL. ? Conclusions: Nymphoides aquatica grows sympodially, forming a rhizome composed of successive basic sympodia and expanded sympodial units. Variations on these types of sympodial growth help explain the branching patterns and leaf morphologies described for other Nymphoides species. Monitoring how these two sympodial phases are affected by water depth provides an ecologically meaningful way to assess N. aquatica's responses to altered hydrology.     

Pollination ecology and reproductive success in Jack-in-the-pulpit (Arisaema triphyllum) in Québec (Canada)

Pollination ecology and reproductive success of Jack-in-the-pulpit ( Arisaema triphyllum ) were studied in two natural populations in Québec, Canada. Individual A. triphyllum plants can be of three types: male, female or bisexual. In both populations studied, the presence of bisexual inflorescences was not negligible (13%), where 'female' and 'male' bisexual plants were categorised according to the relative number of stamens and ovaries. 'Male bisexual' plants produce only pollen and 'female bisexual' plants produce only fruit. Hence, A. triphyllum is a true dioecious plant, as each plant only reproduces through either the male or the female function. 'Female bisexual' plants were equivalent to female plants in terms of visitation rate by insects, fructification rate and production of berries and seeds. Neither agamospermy in female plants nor self-pollination in 'female bisexual' plants was found, thus A. triphyllum relies on insects for cross-pollination. Despite the long flowering cycle, a low visitation rate was documented: only 20–40% of inflorescences were visited, according to gender, by a mean of 1.5 insects. In this study, Mycetophilidae represented the most generically diversified and abundant family, as well as the most efficient insect pollinator, especially the genera Docosia and Mycetophila .     

An architectural model for Eleocharis: morphology and development of Eleocharis cellulosa (Cyperaceae)

Species of Eleocharis are prominent in aquatic and wetland habitats and serve as models for study of physiological adaptations to aquatic environments. The genus has an unusual morphology because the major photosynthetic organ is the stem. In order to define an architectural model for the genus to understand the evolution of this morphology, we examined mature morphology and development of E. cellulosa in living and fixed material using light and scanning electron microscopy. Eleocharis cellulosa has sympodial, vertical shoots that produce the photosynthetic culms and horizontal shoots that mix monopodial and sympodial development. Each sympodial unit produces three bracts, an elongated photosynthetic internode, then a fourth bract and an inflorescence that either aborts on vegetative culms or expands on reproductive culms. On each sympodium, the first bract subtends a precocious axillary bud that reiterates the sympodial unit; the second bract subtends a bud that develops the horizontal shoot. In both horizontal and vertical shoots, the internode below the second bract is produced by both the second bract and the renewal shoot. Sympodial growth is present in seedlings. In other species of Eleocharis, the structure of the sympodial unit is conserved but morphological diversity develops from variation in horizontal shoot growth.     

Morphology and development of the reproductive shoots of Lilaea scilloides (Poir.) Hauman (Alismatidae)

Shoots of adult plants of Lilaea scilloides have a sympodial form. Each unit of the sympodium bears a single sheathing prophyll (which is the only kind of foliage leaf produced in the adult) and terminates in an inflorescence. The prophyll subtends the next unit of the sympodium. A further accessory bud can form in association with each unit. This bud repeats the pattern of the main sympodium, giving the plant a tufted habit. Five different kinds of flower can be identified in the inflorescence: a unisexual male flower with a single perianth member and adnate stamen; a bisexual flower, with a single perianth member and adnate stamen, and a single carpel with an anatropous bitegmic ovule; a unisexual female flower with a single perianth member and carpel; a unisexual female flower comprising only a single carpel; and a female flower comprising only a single carpel with a very long filamentous style. The first four kinds occur in the upper part of the inflorescence which is normally elevated on a scape, while the last kind is restricted to the base of the inflorescence. In the position of the basal flowers several variations have been observed in cultivated material. These include branching associated with the basal flowers, which results in the development of additional basal flowers or inflorescences, and even total replacement of a basal flower by an inflorescence or a branching structure bearing flowers. A review of past literature includes a clarification of some persistent errors which have confused the taxonomic position of the plant and the morphological interpretation of the reproductive appendages.     

Evolutionary and morphometric implications of morphological variation among flowers within an inflorescence: a case-study using European orchids

BACKGROUND AND AIMS: This study explores the previously largely ignored morphological variation that occurs among flowers within a single inflorescence. METHODS: Variation in four metric parameters (labellum length and width, spur length and width) that together strongly influence pollination frequency is documented within the simple racemose inflorescences of eight individuals that represent a primary hybrid and six species of European orchids. KEY RESULTS: Regression of each parameter against the location of each flower on the inflorescence, and calculation of correlation coefficients for each pair of parameters within each inflorescence, demonstrate significant decoupling of labellum and spur development, despite the fact that they are different portions of the same floral organ. Spur length and diameter are constant across inflorescences of Dactylorhiza other than the vestigial-spurred D. viridis, whereas in other genera spur length declines in parallel with labellum dimensions. These differences are likely to reflect selection pressures or developmental constraints. Strong negative deviations from the regression line for one or more parameters are evident in occasional flowers, occurring most frequently in the lowermost and uppermost one or two flowers, and so reflecting transitions in meristematic behaviour. Thus, population-level morphometric studies are best conducted on flowers taken from approximately the mid-point of the inflorescence. Moreover, in the two relatively large inflorescences where lower flowers were removed for measurement before the upper flowers had opened, labellum size increased significantly in the flowers immediately above the excisions, suggesting that excision liberated resources that were diverted into the opening buds. Repeat measurement of all flowers from one selected inflorescence demonstrated typical measurement errors of only +/- 30-80 micro m, irrespective of the size of the structure studied. If flowers are not mounted and measured immediately following excision, modest negative deviations of 30-50 micro m result from post-mounting shrinkage; this occurs less rapidly in the spur than in the thinner labellum, which should therefore be measured first. Variation in all four parameters among all the flowers of a single inflorescence is between 42 % and 107 % of that observed between a similar number of flowers sampled from a consistent location on different (but conspecific and coexisting) inflorescences. CONCLUSIONS: This result demonstrates the strong influence of epigenesis on flower morphology and further emphasizes the importance of (a) sampling from a consistent location within the inflorescences under comparison, (b) interpreting morphometric ordinations hierarchically, building from individuals to infraspecific taxa and species via populations, and (c) considering in any microevolutionary study the potentially profound effects of the cline in flower size within each inflorescence.