No abstract

Quantitative real-time PCR (RT-qPCR) is a reliable method for assessing gene expression, provided that suitable reference genes are included to normalize the data. The stability of expression of eight potential reference genes, namely, tubulin (alpha-2,4 tubulin), actin, EF1 α (elongation factor 1 α), UBC (ubiquitin C), GAPDH (glyceraldehyde-3-phosphate dehydrogenase), psaA (photosynthesis-related plastid gene representing photosystem I), PP2Acs (catalytic subunit of protein phosphatase 2A), and PGK (phosphoglycerate kinase), was assessed in chrysanthemum plants subjected to aphid infestation, heat stress or waterlogging stress using geNorm software. The widely used reference gene EF1 α performed well for aphid infested plants but poorly for waterlogged ones. The catalytic subunit of protein phosphatase 2A (PP2Acs) was the best performing one during heat and waterlogging stress, but was the worst during aphid infestation. The commonly used reference gene actin was generally the least stable of the set. No single gene was suitable for normalization on its own. The choice of reference gene(s) is an important factor in gene expression studies based on RT-qPCR.

Reproductive barriers often exist in the crosses between Dendranthema grandiflorum (Ramat.) Kitamura and its wild species and seriously result in low seed set, consequently reducing breeding efficiency. For the purpose of revealing the factors leading to low seed set, we investigated pollen viability, germination behavior of pollen grains on stigmas and embryo development in the crosses between D. grandiflorum and three wild species, D. nankingense (Nakai) Tzvel., D. indicum (L.) Des Moul. and D. zawadskii (Herb.) Tzvel. using technique of paraffin section, and light, fluorescence and scanning electron microscopy. The results indicated pollen viability of three wild species ranged from 20 to 25%. In the cross between D. grandiflorum and D. nankingense, very few pollen grains germinated on stigmas after pollination and most of them germinated abnormally. In addition, normal embryos were observed in 12% ovaries at 8 days after pollination and thereafter all the embryos aborted. In other two crosses, many pollen grains germinated on stigmas and pollen tubes penetrated stigmas normally after pollination.Moreover, normal embryos were observed in over 50% ovaries from 8 to 15 days after pollination in the cross between D. grandiflorum and D. indicum, and seed set was 59%. In the cross between D. grandiflorum and D. zawadskii, normal embryos were observed in 52% ovaries at 8 days after pollination. After that, however, most embryos degenerated and seed set was only 9%. These data suggest that pollen viability has no significant effects on seed set of the three crosses. Very few germinated pollen grains on stigmas and abnormal growth of most pollen tubes before fertilization, and embryo abortion are the main factors causing failure of the cross between D. grandiflorum and D. nankingense, whereas only embryo abortion is a main factor resulting in low seed set in the cross between D. grandiflorum and D. zawadskii and no barriers occur in the cross between D. grandiflorum and D. indicum.

The instability and low inferior catalytic activity of metal-halide perovskite nanocrystals are crucial issues for promoting their practical application in the photocatalytic field. Herein, we in situ coat a thin graphdiyne (GDY) layer on CsPbBr3 nanocrystals based on a facile microwave synthesis method, and employ it as a photocatalyst for CO2 reduction. Under the protection of GDY, the CsPbBr3-based photocatalyst delivers significantly improved stability in a photocatalytic system containing water concomitant with enhanced CO2 uptake capacity. The favorable energy offset and close contact between CsPbBr3 and GDY trigger swift photogenerated electron transfer from CsPbBr3 to doping metal sites in GDY, boosting a remarkable improvement in the photocatalytic performance for CO2 reduction. Without adding traditional sacrificial reductants, the cobalt-doped photocatalyst achieves a high yield of 27.7 μmol g–1 h–1 for photocatalytic CO2 conversion to CO based on water as a desirable electron source, which is about 8 times higher than that of pristine CsPbBr3 nanocrystals.

The well‐known toxicity of lead‐halide‐perovskite (LHP) nanocrystals limits their commercial applications in photocatalysis. Herein, an in situ controlled growth strategy is reported for lead‐free perovskite nanocrystals (Cs3Bi2I9) on the surface of ultrathin Bi2WO6 nanosheets through co‐sharing Bi atoms, to generate a direct Z‐scheme heterojunction of Cs3Bi2I9/Bi2WO6. Co‐sharing of the Bi atom can enable intimate contact and strong electron coupling between Cs3Bi2I9 and Bi2WO6, which can effectively promote the interfacial charge transfer between Cs3Bi2I9 and Bi2WO6 complying with a Z‐scheme pathway. The resulting efficient charge transfer and well‐preserved redox ability of Cs3Bi2I9/Bi2WO6 heterojunction endow it with a significant improvement of photocatalytic activity for the conversion of CO2‐to‐CO integrated with water oxidation, exhibiting a fourfold increase compared with pure Cs3Bi2I9 nanocrystals. This study paves a new avenue for the construction of efficient Z‐scheme heterojunction based on lead‐free halide perovskite, which should stimulate further passion on the development of high performance of lead‐free halide perovskite materials for photocatalytic application.

No abstract

Phytochelatin synthase (PCS) is a key enzyme involved in the synthesis of phytochelatins, which are thought to play important roles in heavy metal detoxification. The sacred lotus (Nelumbo nucifera), one of the most popular ornamental species, has been shown to be a potential phytoremediator of heavy metal polluted water. However, the phytochelatin synthase gene in N. nucifera has not been identified yet. Here, we report the isolation and function characterization of a N. nucifera homologue of phytochelatin synthase. The sequence obtained shares a high degree of similarity with PCSs from other plant species and was named as Nelumbo nucifera phytochelatin synthase1 (NnPCS1). By using quantitative RT-PCR, we found that the expression of NnPCS1 in leaves of N. nucifera was dramatically increased in response to Cadmium (Cd) treatment. We further showed that, when exposed to Cd stress, Arabidopsis transgenic plants heterologous expressing NnPCS1 accumulated more Cd when compared with wild type. These results suggest that NnPCS1 involved in the response of N. nucifera to Cd stress and may represent a useful target gene for the phytoremediation of Cd-polluted water.

In our earlier study, pre-fertilization barrier was one of the main factors causing the failure of the wide hybridization between Chrysanthemum grandiflorum 'Yuhuaxingchen' and C. nankingense, and seriously restricted the utilization of the excellent chrysanthemum germplasm, C. nankingense. In order to overcome the pre-fertilization barrier and obtain some hybrids, we carried out wide hybridization between them again in this study, and tentatively adopted three pollination techniques including mentor pollen, delayed pollination, and gibberellic acid treatment. The average number of pollen grains germinating on stigma at 24 h after pollination and the percentage of embryo were investigated with a temporary mount method and the technique of fluorescence microscopy. It was found that, compared with the control, delayed pollination, gibberellic acid treatment, and mentor pollen significantly increased the average number of pollen grains germinating on each stigma at 24 h after pollination by approximately 152, 235, and 182%, respectively. In addition, all the three pollination techniques significantly increased the percentage of normal embryos at different periods after artificial pollination in comparison to the control. Furthermore, seed sets of the crosses using the three special pollination techniques were 1.1, 1.4, and 2.0%, respectively, whereas we did not obtained any seeds in the control. Taken together, these results suggest that delayed pollination, gibberellic acid treatment, and mentor pollen are three useful pollination techniques for overcoming pre-fertilization barriers and increasing seed set in the wide hybridization between C. grandiflorum 'Yuhuaxingchen' and C. nankingense, and they may be widely applied for increasing breeding efficiency in other chrysanthemum wide hybridization facing similar pre-fertilization barriers.