Effect of plant growth regulators on two different types of eggplant flowers regarding style length and fruit setting

Aim of study: (i) to explore differences between eggplant flowers capable of setting fruit including long (LGs) and medium style flowers (MEs) and those which suffer from severe problems with fertility and fruit setting including short style ones (SRTs); (ii) to study the effect of plant growth regulators on floral morphology and fruit setting. Area of study: Isfahan University of Technology, Isfahan, Iran, 2017 and 2018. Material and methods: First the floral morphology and initial fruit setting of 13 eggplant genotypes from Iran were investigated. Then the differences between LGs and SRTs of two genotypes were explored. Finally, the effect of 1-naphthaleneacetic acid (NAA) and spermidine (Spd) on floral morphology and initial and final fruit setting of these two genotypes was determined. Main results: Results showed SRTs were not capable of fruit setting. Compared to SRTs, LGs had larger central canals, higher protein, total sugar, reducing sugar and K concentrations, as well as longer polar axis and pollen tubes and greater pollen viability. Although 1.5 mM Spd and 20 mg L-1 NAA resulted in increasing of LGs and MEs, and also total initial fruit set, surprisingly, no significant differences were observed in the final yield and final fruit set between the control and these treatments. Researching highlights: Since the rate of fruit dropping was higher in those treatments compared to the control, plants with more SRTs likely regulate their final load by abscising their flowers, and plants with more LGs regulate them by abscising their fruits.

Reproductive biology of Ophiorrhiza caudata C.E.C.Fisch. (Rubiaceae), an endemic and endangered creeping perennial herb of the Western Ghats, India

Ophiorrhiza caudata is a creeping, perennial herb distributed along wet and shady areas. The species is distylous with two distinct floral morphs: pin and thrum. Flowering usually occurs during the monsoon season. No particular difference was noticed in the flowering phenology of the two morphs. Presently the species is self-incompatible, however, it shows a tendency towards intramorph compatibility. Fruit set is above 60% in open pollination and intermorph pollination. Bees and butterflies are the major pollinators. The pollen flow between the two floral morphs varies depending upon floral morphology and pollinators. Fruit is a bi-valved capsule which dehisces by a splashing drop mechanism. The seeds are very minute. The rate of seed germination and seedling establishment in the wild condition is very poor due to adverse climatic factors. Ophiorrhiza caudata is struggling for survival in its natural habitat, where habitat fragmentation, climatic factors and poor seedling establishment could account for its narrow distribution.

A new Dionysia (Primulaceae) species from southern Turkey, the most western species of the Irano-Turanian genus

A new Dionysia species, D. zeynepiae, is described from Antakya, a Mediterranean province in southern Turkey. It differs from all other known species of the genus by the presence of the trifid corolla lobes (vs. entire, emarginate or bifid lobes). This is the most western and most separated population of this mostly Irano-Turanian genus, which is distributed mainly in the Zagros Mountains (Iran) and adjacent areas. The floral morphology of the heterostylous flowers is also described in detail.

Crepidium sect. Crepidium (Orchidaceae, Malaxidinae)—Chemical and Morphological Study of Flower Structures in the Context of Pollination Processes

Crepidium is a large genus of mainly pantropical orchids. The lips of its flowers are upwardly directed and do not serve as landing platforms for pollinators. This role is assumed by the dorsal sepal and/or gynostemium. Information about the pollination and floral morphology of this genus is scarce. To date, no papers have been published on these topics. Field observations have revealed that the flowers are visited by small flies, midges, fruit flies, other small dipterans, ants, spiders, and mites. Preliminary observations revealed at least two forms of small liquid droplets secreted on the lip surface of Crepidium species: simple secretions from epidermal cells, and cell sap released upon the rupturing of raphide-producing cells. Further research revealed that this was the first time liquid secretion was recorded in this genus. Floral secretions were subjected to sequential organic solvent extraction and gas chromatography–mass spectrometry (GC–MS). Floral parts were investigated by means of scanning (SEM) and transmission electron microscopy (TEM), and histochemical tests. The presence of liquid droplets on the lip of Crepidium, the presence of a food reward, and the sequence of raphide development are reported here for the first time.

Taxonomic notes on Agapetes (Ericaceae) from Xizang, China: Agapetes leiocarpa, a new synonym of A. atrosanguinea, and an updated description of A. camelliifolia

Based on field investigations and a review of relevant literature and specimens, Agapetes leiocarpa is shown to be conspecific with A. atrosanguinea and thus is reduced as a synonym under the latter. The floral morphology of A. camelliifolia is described for the first time based on living collections from the wild. Revised descriptions, color plates and taxonomic notes of these two species are also provided.

Comparative Floral Morphology and Anatomy of Gagea s. str. and Lloydia

Flowers of the five species from the four sections of the genus Gagea (that is, G. lutea , G. pusilla , G. reticulata , G. fragifera , and G. serotina (syn. Lloydia serotina ) were investigated by light microscopy. All investigated species had similar flower organization, vertical zonality of the gynoecium, and floral vascularization. In all species, the flowers were trimerous, with the superior ovary and short complete or semicomplete syntepalous zone at the base. The presence of the syntepalous zone allows consideration of such flowers as an intermediate between hypogynous and perigynous. All investigated species had nectaries at the base of the tepals. However, in Gagea s. str., they were represented by relatively small nectariferous areas of the tepals located at the beginning of the synascidiate zone of the gynoecium. In contrast, the nectaries in G. serotina were represented by elongated tepalar outgrowths located higher, at the level of the fertile symplicate zone of the gynoecium. Considering reports on the potential peltate origin of the nectaries in G. serotina , it is probably incorrect to interpret them as homologous to the nectaries in Gagea s. str. The gynoecium in the studied species demonstrated identical vertical zonality with synascidiate, symplicate, and asymptomatic zones, and corresponded to type C of the syncarpous gynoecium. At the base of the ovary, three carpels were congenitally isolated (primary synascidiate zone); however, they were isolated only postgenitally (secondary synascidiate zone). This secondary synascidiate zone originated from a symplicate zone due to the fusion of the carpelar margins. Although it looks like a synascidiate zone, for correct interpretation of the gynoecium’s vertical structure, it should be considered symplicate. The vascularization of the flower in all investigated species was similar, with the participation of lateral vascular bundles in the supply of placentas.

Unraveling the identity of Paepalanthus decorus (Eriocaulaceae)

Paepalanthus decorus was described by Delia Abbiatti from a single collection of individuals made by Carlos Luis Spegazzini in Uruguaiana, Rio Grande do Sul state, Brazil, deposited at the La Plata Museum. The species is known only from the type specimens, which were unusual for being collected far to the south of the distribution of the other species included in P. sect. Diphyomene. In recent nomenclatural treatments for P. sect. Diphyomene, P. decorus was disregarded, remaining known only from its original publication. Here, we critically evaluate the protologue, type specimens, and the vegetative and floral morphology of this species. As a result, we propose its synonymization under P. flaccidus. A detailed comparison of these species is provided, along with comments on typification, with a lectotype designated for P. flaccidus.

Recruitment of an ancient branching program to suppress carpel development in maize flowers

Floral morphology is immensely diverse. One developmental process acting to shape this diversity is growth suppression. For example, grass flowers exhibit extreme diversity in floral sexuality, arising through differential suppression of stamens or carpels. In maize, carpels undergo programmed cell death in half of the flowers initiated in ears and in all flowers in tassels. The HD-ZIP I transcription factor gene GRASSY TILLERS1 (GT1) is one of only a few genes known to regulate this process. To identify additional regulators of carpel suppression, we performed a gt1 enhancer screen, and found a genetic interaction between gt1 and ramosa3 (ra3). RA3 is a classic inflorescence meristem determinacy gene that encodes a trehalose-6-phosphate (T6P) phosphatase (TPP). Dissection of floral development revealed that ra3 single mutants have partially derepressed carpels, whereas gt1; ra3 double mutants have completely derepressed carpels. Surprisingly, gt1 suppresses ra3 inflorescence branching, revealing a role for gt1 in meristem determinacy. Supporting these genetic interactions, GT1 and RA3 proteins colocalize to carpel nuclei in developing flowers. Global expression profiling revealed common genes misregulated in single and double mutant flowers, as well as in derepressed gt1 axillary meristems. Indeed, we found that ra3 enhances gt1 vegetative branching, similar to the roles for the trehalose pathway and GT1 homologs in the eudicots. This functional conservation over ~160 million years of evolution reveals ancient roles for GT1-like genes and the trehalose pathway in regulating axillary meristem suppression, later recruited to mediate carpel suppression. Our findings expose hidden pleiotropy of classic maize genes, and show how an ancient developmental program was redeployed to sculpt floral form.