Hexose translocation mediated by SlSWEET5b is required for pollen maturation in Solanum lycopersicum

Pollen fertility is critical for successful fertilization and, accordingly, for crop yield. While sugar unloading affects growth and development of all types of sink organs, the molecular nature for sugar import to tomato pollen is poorly understood. However, SWEET transporters have been proposed to function in pollen development. Here, qRT-PCR revealed that SlSWEET5b was markedly expressed in flowers when compared to the remaining tomato SlSWEETs; particularly, in the stamens of maturing flower buds undergoing mitosis. Distinct accumulation of SlSWEET5b-GUS fusion proteins was present in mature flower buds, especially in anther vascular and inner cells, symplasmic isolated pollen cells and styles. The demonstration that GFP fusion proteins located to the plasma membrane support the idea that the SlSWEET5b carrier functions in apoplasmic sugar translocation during pollen maturation. Such function is in line with data from yeast complementation experiments and radiotracer uptakes, showing that SlSWEET5b operates as a low affinity hexose-specific passive facilitator, with a KM of ~36 mM. Most importantly, RNAi-mediated suppression of SlSWEET5b expression resulted in shrunken nucleus-less pollen cells, impaired germination and low seed yield. Interestingly, stamens from SlSWEET5b-silenced tomato mutants contained significantly lower amounts of sucrose and increased invertase activity, pointing to reduced carbon supply and perturbed sucrose homeostasis in this tissue. Taken together, our findings reveal an essential role of SlSWEET5b in mediating apoplasmic hexose import into phloem unloading cells and into developing pollen cells to support pollen mitosis and maturation in tomato flowers.One-sentence SummaryPlasma-membrane-localized SlSWEET5b facilitates a sequential hexose flux, from phloem to anther cells and from anther locule to pollen, to support pollen maturation and fertility in tomato flowers.

Comprehensive analysis of the differentially expressed receptor-like kinase genes in responding to pollination in A. thaliana and B. napus

Background Successful sexual reproduction in flowering plant requires extensive communications between male and female organs and tissues. Although RLKs have been proved to play critical roles in these communications, so far the identified RLKs are still limited. Here we performed a comprehensive analysis on differentially expressed RLKs in responding to pollination in Arabidopsis thaliana and Brassica napus to contibute to further analysis on RLKs’ function in male-female communication. Result In this study, a total of 2,583 B. napus AtRLK orthologs were obtained. 89 AtRLKs showed obvious expression level changes after pollination in A. thaliana or in B. napus. Although 30 differentially expressed AtRLKs were opened anthers and anthers of mature flower before opening preferentially expressed or hydrated pollen-enriched, up to 79 AtRLKs corresponding to 129 B. napus orthologs showed obvious expression level changes at different time points after pollination. Among 89 differentially expressed AtRLKs after pollination, only 7 AtRLKs were shared by differently expressed genes during in vitro pollen tube growth, 3 of 7 AtRLKs’ expression level change tendency after pollination and during PTG were different. Conclusions Amount to 89 AtRLKs were differentially expressed in responding to pollination in A. thaliana and B. napus, and their expression level changes should be mainly induced by pollen-stigma interaction, several of them had been proved to function in male-female communication in the former reports.

COMPARISION OF PHYTOCHEMICALS IN THE FLOWER BUDS, PEDICELS AND LEAVES OF SYZYGIUM AROMATICUM (L.) MERRIL AND PERRY

Objective: To analyse and compare the major chemical components in the flower buds, pedicels and leaves of Syzygium aromaticum by Gas-Chromatography Mass spectrometry technique. Methods: Healthy and mature flower buds, pedicels and leaves were shade dried and pulverized using a mechanical grinder. The powder was successively extracted with ethanol (40-60o C). The extracts were concentrated under reduced pressure in a rotary evaporator. The ethanolic extracts of the plant parts such as leaves, pedicels, and buds were used for GC-MS analysis.Results: The major constituent is eugenol. Pedicels contain 79.75% eugenol, buds contain 74.12% eugenol and leaves contain 51.03% eugenol. In addition to eugenol, other important components are Acetyl eugenol, Caryophyllene, Humulene and Caryophyllene oxide.Conclusion: Eugenol has a wide range of medicinal properties such as antiseptic, anaesthetic, analgesic anti-inflammatory. Commercially pedicel is not used for eugenol extraction. Present study has revealed that it could be used as a promising one in pharmaceutical industry in addition to flower buds.

A new species of Eugenia (Myrteae, Myrtaceae) from the submontane forest of northern Atlantic Forest

Eugenia studerae is here described and illustrated. This species is restricted to submontane forests of northern Atlantic Forest and known only for the Alagoas state. Eugenia studerae is morphologically related to E. hirta. They share the small leaves, inflorescence with reduced main axis and subglobose and smooth fruits, but E. studerae differs by the inflorescence usually with 3–4 mature flowers/fruits, smaller and acute calyx lobes and the restricted distribution in submontane forests (vs. inflorescence usually with 1 mature flower/fruit, larger and rounded calyx lobes and the distribution in lowland coastal forests in E. hirta).

Estimation of Pyrethrum Flower Number Using Digital Imagery

Flower number is the primary determinant of yield in pyrethrum (Tanacetum cineariifolium). Traditional estimates of flower numbers use physical harvesting of flowers, which is time consuming, destructive, and complicated. The precision of flower number estimates may be highly influenced by spatial heterogeneity of plant density and vigor. Here, we examined the potential for digital image analysis to enable rapid, nondestructive assessment of flower number. This technique involved removal of pixels with color profiles not typical of the disc florets of pyrethrum. Particle counting was then performed using defined size and shape parameters to estimate flower numbers. Estimates of flower number based on image analyses were correlated with physical harvests of flowers, with estimates representing about an average of 32% of total flower numbers present within a sampling unit. This relationship was consistent across all observed flower densities. Covariate analysis indicated that occurrences of crop lodging and over mature flower canopies had significant, detrimental effects on system predictions. Pyrethrum flowers were spatially aggregated within fields with the degree of aggregation greatest at the lowest flower densities. Based on modeled flower distributions, eight quadrats (0.49-m2 sampling unit) were sufficient to achieve a cv of 0.1 in a 600-m2 plot area in all but the lowest flower densities. The utility of this approach for biomass assessment in pyrethrum and other Compositae is discussed.

Characterization of Developmental- and Stress-Mediated Expression of Cinnamoyl-CoA Reductase in Kenaf (Hibiscus cannabinusL.)

Cinnamoyl-CoA reductase (CCR) is an important enzyme for lignin biosynthesis as it catalyzes the first specific committed step in monolignol biosynthesis. We have cloned a full length coding sequence ofCCRfrom kenaf (Hibiscus cannabinusL.), which contains a 1,020-bp open reading frame (ORF), encoding 339 amino acids of 37.37 kDa, with an isoelectric point (pI) of 6.27 (JX524276,HcCCR2). BLAST result found that it has high homology with other plant CCR orthologs. Multiple alignment with other plant CCR sequences showed that it contains two highly conserved motifs: NAD(P) binding domain (VTGAGGFIASWMVKLLLEKGY) at N-terminal and probable catalytic domain (NWYCYGK). According to phylogenetic analysis, it was closely related to CCR sequences ofGossypium hirsutum(ACQ59094) andPopulus trichocarpa(CAC07424).HcCCR2showed ubiquitous expression in various kenaf tissues and the highest expression was detected in mature flower.HcCCR2was expressed differentially in response to various stresses, and the highest expression was observed by drought and NaCl treatments.

Beneficial Role of 1-Methylcyclopropene for Cut Lupinus havardii Racemes Exposed to Ethephon

The raceme of Lupinus havardii Wats. (Big Bend bluebonnet) is a new greenhouse specialty cut flower, but postharvest life is limited by ethylene sensitivity. The authors studied the effects of 160 nL·L−1 1-methylcyclopropene (1-MCP) with 0 to 6 days exposure to a 50-μm vase solution of ethephon [(2-chloroethyl) phosphonic acid, CEPA] on raceme postharvest quality indices and mature flower cell membrane permeability. With no CEPA, 1-MCP delayed postharvest losses in fresh weight and mature flower retention, and extended vase life longevity (VLL) by 1 to 4 days relative to a non-1-MCP control. With 2 days or more of CEPA, 1-MCP deferred raceme fresh weight loss and the abscission of both mature and newly opened flowers from 3 days to 5 days. There was a relatively strong protective effect of 1-MCP on raceme fresh weight, flower retention, and newly opening flowers in the presence of CEPA compared with the absence of CEPA. The greatest raceme VLL (7.2 days) was obtained for 1-MCP-treated racemes that did not receive CEPA in the vase. Although VLL was reduced by CEPA, VLL was consistently greater (by ≈2 days) after 1-MCP treatment relative to no 1-MCP treatment and irrespective of CEPA's duration. As expected, electrolyte leakage increased with individual flower development and between 1 day and 6 days in the vase. Unexpectedly, however, the 5-day postharvest increase in leakage was intensified by 1-MCP treatment if the racemes were exposed to 1 hour of CEPA in the vase solution. Electrical conductivity measurements suggested that, in the latter treatment (+1-MCP, +CEPA), increased levels of diffusible electrolytes that had yet to be exported to the expanding apical meristem (delayed raceme development) contributed to the higher leakage. Results also demonstrate good potential for quality maintenance of L. havardii racemes by using 1-MCP, and that in addition to flower retention, raceme fresh weight and flower opening should be considered in developing VLL criteria for this new specialty crop.

Correlative Supply and Demand Functions in Lupinus havardii: A Forgotten Side of Cut Flower Physiology?

Correlative control of long-distance transport processes consists of an attraction or mobilizing power of a sink organ coupled to internal degradative reactions in a target source organ and the reallocation of its resources. This phenomenon is widely recognized in the agronomic whole plant literature but poorly recognized in the floriculture literature. We calculated supply and demand balances for water, total dry matter (TDM), and minerals during a 6-day postharvest evaluation of the spatially diverse, detached, indeterminate inflorescence of Lupinus havardii Wats. ‘Texas Sapphire’ held in deionized water. The apex approximately doubled its original (harvest day) amounts of total N, P, K, Mg, and S and increased its TDM and water content by 55% and 85%, respectively, all at the expense of lower-most mature flowers. Net export from the lower mature flower fraction and, when applicable, upper mature flowers, accounted for the following apical gains: 46% of TDM, 102% of water, 100% of N, 94% of P, 99% of K, and 54% of Mg and S. Directed reallocation of resources from the senescing lower mature flowers (the main “target”) to the apical sink (the “mobilizing center”) bore a marked resemblance to the coupling of remote sink demand with vegetative decline reported in monocarpic plants (i.e., vegetative-to-reproductive exchanges), but with two distinguishing characteristics: 1) the TDM and mineral exchanges were strongly restricted to flowering units, and 2) the contributions of water, N, P, and K exports to apical sink demand were at or near 100%. This article is the first that we are aware to provide an internal supply and demand balance sheet reflecting, quantitatively, the postharvest reallocation of internal resources from mature reproductive tissues to generative reproductive tissues of a cut inflorescence.

Durian Floral Differentiation and Flowering Habit

Flower bud differentiation and the flowering habit of durian (Durio zibethinus Murray) `Mon Thong' from budbreak to anthesis were investigated at the Chantaburi Horticultural Research Center in Thailand. Clusters of flower buds appeared at the end of November on primary or secondary scaffold branches near where a flower cluster occurred the previous year. Anatomical observations revealed that the development of floral organs was acropetal; the five fused epicalyx forming a large, elongated envelope enclosing the sepals, petals, stamen and fused multi-carpellate pistil. Floral organ development was completed in early January. The mature flower bud more than doubled in size one day before anthesis, with anthesis starting around 1600 hr and ending ≈1900 hr. The anthers did not dehisce until the completion of flowering. This change induced heterostyly in this cultivar, which promoted out-crossing by reducing the possibility of self-pollination. Aromatic nectar that attracted insects to the flower was secreted during anthesis. This is the first report to have clarified the overall flowering process in durian and provides the basic information for elucidating reproductive biology of durian in future research.