Nectar robbing in bellflower (Sesamum radiatum) benefited pollinators but unaffected maternal function of plant reproduction.

Nectar robbing - foraging nectar illegitimately - has negative, neutral, or positive effects on maternal function of plant reproduction and/or on pollinators. It has been suggested that nectar robbing has a non-negative effect on maternal function of plant reproduction in autogamous and mixed breeding plants; however this hypothesis requires deeper understanding with more studies. We investigated the impact of natural nectar robbing on maternal function of plant reproduction and visitation characteristics of pollinators in Sesamum radiatum, an autogamous plant. Pollinators were observed on unrobbed open flowers and robbed open flowers. In robbed flowers, pollinators' visit type and foraging time were examined. The seed sets of these flower types were examined. Xylocopa latipes was both a primary robber and a legitimate pollinator, X. bryorum was an exclusive primary robber, and Megachile disjuncta was a cosmopolitan pollinator. In robbed flowers, most of the pollinators foraged mostly as secondary nectar robbers. The foraging time shortened considerably when pollinators robbed nectar - a positive effect on pollinators' foraging efficiency. Robbing did not negatively affect seed set - a neutral effect on the plant's reproduction. Our study agrees that nectar robbing might have a non-negative effect on reproduction in autogamous and mixed breeding plants.

Effects of Different Pollens on Primary Metabolism and Lignin Biosynthesis in Pear.

To investigate the effect of pollination on the fruit quality of 'Dangshan Su' pear, 'Dangshan Su' was fertilized by the pollen of 'Wonhwang' (Pyrus pyrifolia Nakai.) (DW) and 'Jingbaili' (Pyrus ussuriensis Maxim.) (DJ). The analysis of primary metabolites was achieved through untargeted metabolomics, and the quantitative analysis of intermediate metabolites of lignin synthesis was undertaken using targeted metabolomics. The untargeted metabolomics analysis was performed via gas chromatography-mass spectrometry (GC-MS). The targeted metabolomics analysis was performed using ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) under the multiple reaction monitoring (MRM) mode. The results showed that the metabolite content was significantly different between DW and DJ. Compared with that in DJ, the sugar and amino acid content in DW was higher and the fatty acid content was lower at 47 days after pollination (DAPs), and the sugar, amino acid, and fatty acid content in DW was lower at 63 DAPs. The intermediate metabolites of lignin synthesis were analyzed using the orthogonal partial least squares discriminant analysis (OPLS-DA) model, and the differential metabolites at 47 DAPs were p-coumaric acid, ferulic acid, sinapaldehyde, coniferyl alcohol, and sinapyl alcohol. The differential significant metabolite at 63 DAPs was p-coumaric acid. At 47 DAPs and 63 DAPs, the p-coumaric acid level was significantly different, and the p-coumaric acid content was positively correlated with lignin synthesis. The pollination pollen affects the quality of 'Dangshan Su' pear fruit through regulation of the sugar, amino acid, and fatty acid content; at the same time, regulating the levels of intermediate metabolites of lignin synthesis, especially the p-coumaric acid content, to affect lignin synthesis ultimately affects the stone cell content and improves the quality of the pears.

Coloration of the Chilean Bellflower, Nolana paradoxa, interpreted with a scattering and absorbing layer stack model.

MAIN CONCLUSION: An absorbing-layer-stack model allows quantitative analysis of the light flux in flowers and the resulting reflectance spectra. It provides insight in how plants can optimize their flower coloration for attracting pollinators. The coloration of flowers is due to the combined effect of pigments and light-scattering structures. To interpret flower coloration, we applied an optical model that considers a flower as a stack of layers, where each layer can be treated with the Kubelka-Munk theory for diffusely scattering and absorbing media. We applied our model to the flowers of the Chilean Bellflower, Nolana paradoxa, which have distinctly different-colored adaxial and abaxial sides. We found that the flowers have a pigmented, strongly scattering upper layer, in combination with an unpigmented, moderately reflecting lower layer. The model allowed quantitative interpretation of the reflectance and transmittance spectra measured with an integrating sphere. The absorbance spectrum of the pigment measured with a microspectrophotometer confirmed the spectrum derived by modeling. We discuss how different pigment localizations yield different reflectance spectra. The absorbing layer stack model aids in understanding the various constraints and options for plants to tune their coloration.

[Effects of different salt-alkaline stress on seed germination and seedling physiological characteristics of Codonopsis pilosula].

OBJECTIVE: To improve salt resistance of Codonopsis pilosula seeds and seedlings under different salt-alkaline stress, the seed germination and physiological characteristics of seedlings were studied. METHODS: Several physiological indexes of Codonopsis pilosula under different salt-alkaline stress were measured, such as the germination vigor, germination rate, relative germination rate and recovery germination rate,as well as others indexes like the contents of chlorophyll, soluble protein, water and MDA and the activities of POD and SOD. RESULTS: The inhibitory effects of three salts on seed germination were Na2 CO3 > NaCl + Na2 CO3 > NaCl with an increased salt concentration. The contents of chlorophyll, soluble protein and water were found significant different (P < 0.05) from the negative control group, along with the decreased of these indexes. However, positive correlation existed between MDA content and salt treatment concentration. In addition, the change trend of SOD and POD activity were similar. They were increased firstly, and then decreased as the stress intensity extended. CONCLUSION: The seeds and seedlings under different salt-alkaline stress were inhibited, with different inhibitory extent as Na2CO3 > NaCl + Na2 CO3 > NaCl.

[Mating system and causes of low fructification rate by self-pollination of Codonopsis pilosula].

OBJECTIVE: To study four kinds of germplasm resources of Codonopsis pilosula and provide the basal mating systems data for the breeding and cultivation of C. pilosula. METHOD: 0.5% TTC (2,3,5-triphenyl tetrazolium chloride) solution was used for the pollen viability test and benzidineand-H2O2 [1% benzidine in 60% ethanol,hydrogen peroxide (3%), and water, 4:11:22] was used for estimation of the stigma receptivity. The mating systems were tested by out crossing index (OC1), pollen-ovule ratio (P/O) and pollination by bagged and emasculated in the field. RESULT: The pollen viability of C. pilosula reached highly about 80% when the pollen staying in the anther, 2-3 days before the petals opening. The anther began scattering pollen before the day of the petals opening, the pollen viability was the highest about 95%, the pollen stick thickly aroud the stigma and quickliy lost in the next day. The stigma life-span was about 4-5 days, the optimal time for pollination was the first day of the petals opening, when the stigma was highly sticky and yellow. The value of out crossing index (OC1) was 4, pollen-ovule ratio was between 104.84-185.75. The natural fructification rate of cross-pollination by emasculated-treatment was 25.6% 42.4%. The fructification rate and compatible index of self-pollination by bagged- treatment were about 3.3%-6.7% and 3.0-21.8. CONCLUSION: The mating system of C. pilosula is mixed with self-pollination and cross-pollination, prone to cross-pollination. The compatibility of self-pollination is high. The difference of maturing period of pistil and stamen and the lack of polen amount cause low fructification rate of self-pollination.