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Mo1.33C i-MXene nanosheets and poly(3,4-ethylenedioxythiophene):polystyrene sulfonate multifunctional hybrid smart fiber is fabricated with an easily scalable spinning approach and can be used for both supercapacitors and electrochemical transistors.

Two-dimensional (2D) transition metal carbides and carbonitrides, called MXenes, with metallic conductivity and hydrophilic surfaces, show great promise as electrode materials for supercapacitors. ...

Electrochromic (EC) materials that change color with voltage have been widely studied for use in dynamic windows. However, colorless-to-colorful switching with high contrast ratio is generically unattainable, especially for colorless-to-black electrochromic materials with an ultrahigh contrast ratio over the entire visible region. In this work, we developed Nb1.33C MXene-based dynamic windows with colorless-to-black switching of up to 75% reversible change in transmittance from 300 to 1,500 nm. By exploring the electrochromic effects of different electrolytes through in situ optical changes and electrochemical quartz crystal microbalance (EQCM), it is found that electrochromic behavior is greatly influenced by the extent of reversible Li+ insertion/deinsertion between the two-dimensional Nb1.33C MXene nanosheets. In addition, a colorless-to-black EC device based on Nb1.33C with an overall integrated contrast ratio over 80% was successfully constructed by a solution-processable spin coating method. This work enables a simple route to fabricate MXene-based high-performance electrochromic smart windows, which is important for further expanding the application of MXenes to optoelectronic and photonic applications. Funding Agencies|SSF Research Infrastructure Fellow Program [RIF 14-0074]; SSF Synergy Program [EM16-0004]; Knut and Alice Wallenberg (KAW) FoundationKnut & Alice Wallenberg Foundation [KAW2020.0033]; National Natural Science Foundation of ChinaNational Natural Science Foundation of China (NSFC) [61774077]; Guangdong Joint Research Fund [2020A1515110738]; Postdoctoral Research Foundation of ChinaChina Postdoctoral Science Foundation [2020M683187]; Key Projects of Joint Fund of Basic and Applied Basic Research Fund of Guangdong Province [2019B1515120073]; Guangzhou Key laboratory of Vacuum Coating Technologies and New Energy Materials Open Projects Fund [KFVE20200006]

Background Brassica napus is the third leading source of edible oil in the world. Genic male sterility (GMS) lines provide crucial material for harnessing heterosis for rapeseed. GMS lines have been used successfully for rapeseed hybrid production in China. MicroRNAs (miRNAs) play crucial regulatory roles in various plant growth, development, and stress response processes. However, reports on miRNAs that regulate the pollen development of GMS lines in B. napus are few. Results In this study, 12 small RNA and transcriptome libraries were constructed and sequenced for the flower buds from the fertile and sterile lines of two recessive GMS (RGMS) lines, namely, “6251AB” and “6284AB”. At the same time, 12 small RNA and transcriptome libraries were also constructed and sequenced for the flower buds from the fertile and sterile lines of two dominant GMS (DGMS) lines, namely, “4001AB” and “4006AB”. Based on the results, 46 known miRNAs, 27 novel miRNAs on the other arm of known pre-miRNAs, and 44 new conserved miRNAs were identified. Thirty-five pairs of novel miRNA-3p/miRNA-5p were found. Among all the identified miRNAs, fifteen differentially expressed miRNAs with over 1.5-fold change between flower buds of sterile and fertile lines were identified, including six differentially expressed miRNAs between “4001A” and “4001B”, two differentially expressed miRNAs between “4006A” and “4006B”, four differentially expressed miRNAs between “6251A” and “6251B”, and ten differentially expressed miRNAs between “6284A” and “6284B”. The correlation analysis of small RNA and transcriptome sequencing was conducted. And 257 candidate target genes were predicted for the 15 differentially expressed miRNAs. The results of 5′ modified RACE indicated that BnaA09g48720D, BnaA09g11120D, and BnaCnng51960D were cleaved by bna-miR398a-3p, bna-miR158-3p and bna-miR159a, respectively. Among the differentially expressed miRNAs, miR159 was chosen to analyze its function. Overexpression of bna-miR159 in Arabidopsis resulted in decreased seed setting rate, and shortened siliques, illustrating that miR159 may regulate the fertility and silique development in rapeseed. Conclusions Our findings provide an overview of miRNAs that are potentially involved in GMS and pollen development. New information on miRNAs and their related target genes are provided to exploit the GMS mechanism and reveal the miRNA networks in B. napus.

Given the breadth of currently arising opportunities and concerns associated with nanoparticles for biomedical imaging, various types of nanoparticles have been widely exploited, especially for cellular/subcellular level probing. However, most currently reported nanoparticles either have inefficient delivery into cells or lack specificity for intracellular destinations. The absence of well-defined nanoplatforms remains a critical challenge hindering practical nano-based bio-imaging. Herein, the authors elaborate on a tailorable membrane-penetrating nanoplatform as a carrier with encapsulated actives and decorated surfaces to tackle the above-mentioned issues. The tunable contents in such a versatile nanoplatform offer huge flexibility to reach the expected properties and functions. Aggregation-induced emission luminogen (AIEgen) is applied to achieve sought-after photophysical properties, specific targeting moieties are installed to give high affinity towards different desired organelles, and critical grafting of cell-penetrating cyclic disulfides (CPCDs) to promote cellular uptake efficiency without sacrificing the specificity. Hereafter, to validate its practicability, the tailored nano products are successfully applied to track the dynamic correlation between mitochondria and lysosomes during autophagy. The authors believe that the strategy and described materials can facilitate the development of functional nanomaterials for various life science applications. Funding Agencies|STINT Joint China-Sweden Mobility Project [CH2017-7243]; Swedish Research Council (VR)Swedish Research Council [VR 2019-02409, 2020-05437]; China Scholarship Council (CSC)China Scholarship Council; Science and Technology Development Fund, Macau SAR [019/2017/AMJ, 0114/2019/A2]; Carl Tryggers Stiftelse [CTS 19:379]; Swedish Government strategic faculty grant in material science (SFO, MATLIU) in Advanced Functional Materials (AFM) (VR) [Dnr. 5.1-2015-5959]; Centre in Nano Science and technology at LiTH (CeNano); LiU Cancer network at Linkoping University

Conventional methods for gene function study in Brassica campestris have lots of drawbacks, which greatly hinder the identification of important genes' functions and molecular breeding. The clustered, regularly interspaced, short palindromic repeats (CRISPR) and CRISPR-associated protein 9 (CRISPR/Cas9) system is a versatile tool for genome editing that has been widely utilized in many plant species and has many advantages over conventional methods for gene function study. However, the application of CRISPR/Cas9 system in B. campestris remains unreported. The pectin-methylesterase genes Bra003491, Bra007665, and Bra014410 were selected as the targets of the CRISPR/Cas9 system. A single-targeting vector and a multitargeting vector were constructed. Different types of mutations were detected in T0 generation through Agrobacterium transformation. The mutation rate of the three designed sgRNA seeds varied from 20 to 56%. Although the majority of T0 mutants were chimeric, four homozygous mutants were identified. Transformation with the multitargeting vector generated one line with a large fragment deletion and one line with mutations in two target genes. Mutations in Bra003491 were stable and inherited by T1 and T2 generations. Nine mutants which did not contain T-DNA insertions were also obtained. No mutations were detected in predicted potential off-target sites. Our work demonstrated that CRISPR/Cas9 system is efficient on single and multiplex genome editing without off-targeting in B. campestris and that the mutations are stable and inheritable. Our results may greatly facilitate gene functional studies and the molecular breeding of B. campestris and other plants.

Restricted by the energy gap rule, near-infrared (NIR) luminescent materials face great challenges. Here, we report a newly designed and synthesized organic molecule, 5,5′-([1,2,5]thiadiazolo[3,4-c...

To explore the low temperature germination characteristics of rapeseed, 8 main cultivars were selected for germination experiments in incubators at 20℃, 16℃, 12℃ and 8℃, respectively, to measure and analyze the germination potential, germination rate, root length, bud length, etc. The results showed that there was significant difference in the germination potential of tested rapeseeds at temperatures. And the low temperature of 8℃ was significantly reduced the germination potential. With the decrease of germination temperature, the growth of roots and buds were inhibited significantly. There were significant differences both in temperatures and varieties. The germination potential, root length and bud length could be used as the main index to evaluate seed germination of rapeseed under low temperature. In addition, to screen varieties suitable for spring sowing as green manure, the spring sowing test was carried out. The study found that the fresh grass yield of “Huyouzao No.1” was 1712.53 kg/m 2 , which was much higher than other 7 varieties. Its relative root length was second only to “Huyou17” and its relative bud length next to “Huyoufei No.1” at 8℃, respectively. The results can provide a reference for early spring sowing of rapeseed as green manure.

Intracellular lipid metabolism occurs in lipid droplets (LDs), which is critical to the survival of cells. Imaging LDs is an intuitive way to understand their physiology in live cells. However, this is limited by the availability of specific probes that can properly visualize LDs in vivo. Here, an LDs-specific red-emitting probe is proposed to address this need, which is not merely with an ultrahigh signal-to-noise (S/N) ratio and a large Stokes shift (up to 214 nm) but also with superior resistance to photobleaching. The probe has been successfully applied to real-time tracking of intracellular LDs behaviors, including fusion, migration, and lipophagy processes. We deem that the proposed probe here offers a new possibility for deeper understanding of LDs-associated behaviors, elucidation of their roles and mechanisms in cellular metabolism, and determination of the transition between adaptive lipid storage and lipotoxicity as well. Funding Agencies|STINT Joint China - Sweden Mobility Project Program [CH2017-7243]; National Natural Science Foundation of ChinaNational Natural Science Foundation of China [21775001, 21705001]; China Scholarship Council (CSC)China Scholarship Council; Swedish Research CouncilSwedish Research Council [VR 2019-02409]; Swedish Government Strategic Faculty Grant in Material Science (SFO, MATLIU) in Advanced Functional Materials (AFM) [5.1-20155959]; Centre in Nano Science and Nano Technology at LiTH (CeNano); LiU Cancer network at Linkoping University

Solar energy, although it has the highest power density available in terms of renewable energy, has the drawback of being erratic. Integrating an energy harvesting and storage device into photovoltaic energy storage modules is a viable route for obtaining self-powered energy systems. Herein, an MXene-based all-solution processed semitransparent flexible photovoltaic supercapacitor (PSC) was fabricated by integrating a flexible organic photovoltaic (OPV) with Ti3C2Tx MXene as the electrode and transparent MXene supercapacitors with an organic ionogel as the electrolyte in the vertical direction, using Ti3C2Tx thin film as a common electrode. In the quest for a semitransparent flexible PSC, Ti3C2Tx MXene was first used as a transparent electrode for OPV with a high power conversion efficiency of 13.6%. The ionogel electrolyte-based transparent MXene supercapacitor shows a high volumetric capacitance of 502 F cm(-3) and excellent stability. Finally, a flexible PSC with a high average transmittance of over 33.5% was successfully constructed by all-solution processing and a remarkable storage efficiency of 88% was achieved. This strategy enables a simple route for fabricating MXene based high-performance all-solution-processed flexible PSCs, which is important for realizing flexible and printable electronics for future technologies. Funding Agencies|Swedish Energy AgencySwedish Energy Agency [EM 42033-1]; Swedish Government Strategic Research Area in Material Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [200900971]; Swedish Research CouncilSwedish Research Council [2017-04123]; SSF Research Infrastructure Fellow Program [RIF 14-0074]; SSF Synergy Program [EM16-0004]; Knut and Alice Wallenberg (KAW) FoundationKnut & Alice Wallenberg Foundation [KAW 2015.0043]; National Natural Science Foundation of ChinaNational Natural Science Foundation of China [61774077]; Open Fund of the State Key Laboratory of Luminescent Materials and Devices [2018-skllmd-12]; Fundamental Research Funds for the Central UniversitiesFundamental Research Funds for the Central Universities

In order to locate candidate genes related to flowering time, and to provide a basis for genetic improvement and flowering time of Brassica campestris , a natural population composed of 110 B. campestris was used as research materials. Flowering investigation and resequencing were performed on them. The high-quality SNP set obtained by resequencing was used for population evolutionary tree analysis, principal component analysis, population genetic structure analysis and a genome-wide association analysis. The observation results showed there were wide differences in flowering time between different types of B. campestris . The results of population structure analysis showed that 110 materials could be divided into two subgroups. The distribution within each phylogenetic tree was relatively concentrated, and the distribution between different subgroups was closely related to the geographical origin of the material. Genome-wide association analysis revealed that the average LD of the whole B. campestris attenuated LD was 19 kb, and 4 signal sites significantly associated with the flowering schedule type were obtained. Functional annotation was performed on related genes in a certain region upstream and downstream of the physical location of the four associated candidate sites, and 9 candidate transcripts related to flowering time were screened. Further analysis revealed that 9 transcripts contained a total of 4 candidate genes, which were homologous genes of Arabidopsis LOL1 , CAT5 and FAD8 . The results of this study could provide some theoretical basis and clues for obtaining candidate genes related to flowering time of B. campestris and using them to regulate flowering and genetic improvement.

Background Numerous regulatory genes participate in plant thermotolerance. In Arabidopsis, HEAT-INDUCED TAS1 TARGET2 (HTT2) is an important thermotolerance gene that is silenced by ta-siR255, a trans-acting siRNA. ta-siR255 is absent from heading Chinese cabbage (Brassica rapa ssp. pekinensis). Our previous attempt to overexpress the endogenous BrpHTT2 gene of heading Chinese cabbage (B. rapa ssp. pekinensis) failed because of cosuppression. In theory, heading Chinese cabbage can overexpress Arabidopsis HTT2 to improve thermotolerance in the absence of ta-siR255-mediated gene silencing and the weak potential of coexpression. Results To test the potential application of HTT2 in improving crop thermotolerance, we transferred p35S::HTT2 to heading Chinese cabbage. We tested the leaf electrical conductivity, hypocotyl elongation, and survival percentage of p35S::HTT2 plants subjected to high-temperature (38 °C) and heat-shock (46 °C) treatment. The leaf electrical conductivity of p35S::HTT2 seedlings under high temperature decreased but did negligibly change under heat shock. The hypocotyl length of p35S::HTT2 seedlings increased under high temperature and heat shock. The survival rate of p35S::HTT2 seedlings increased under heat shock. BrpHsfs, a subset of heat-shock factor genes, were upregulated in p35S::HTT2 plants under high-temperature and heat shock conditions. In the field, transgenic plants with HTT2 appeared greener and formed leafy heads earlier than wild-type plants. Conclusions Exogenous HTT2 increased the survival rates of heat-shocked heading Chinese cabbage by promoting thermotolerance through decreasing electrical conductivity and extending hypocotyl length. Our work provides a new approach to the genetic manipulation of thermotolerance in crops through the introduction of exogenous thermotolerance genes. Electronic supplementary material The online version of this article (10.1186/s12870-018-1346-x) contains supplementary material, which is available to authorized users.

Rapeseed (Brassica napus L.) is an important oil crop with a huge genome. This study used next generation sequencing technology to develop SSR markers in rapeseed. A total of 213,876 sequence reads were obtained in 58.8 Mb. For these reads, 21,523 SSRs were recovered from 18,575 microsatellites sequences and 8,964 SSR primer pairs were identified. Di- and mono-nucleotides were the most abundant, accounting for 47.5% and 30.7% of all SSRs, respectively. A total of 8,776 SSRs were designed from contigs and 100 SSR primers were tested for validation of SSR locus amplification. Nearly all (94%) of the markers were found to produce clear amplicons and to be reproducible. For these markers, forty-three SSRs showed polymorphic bands in eight rapeseed accessions. Thirty-four SSRs were then applied to 78 rapeseed accessions from China to evaluate the genetic diversity. Result showed that the allele number varied from two to seven, with a mean value of 3.59. The effective allele number of ranged from 1.14 to 3.25, with an average of 2.09. The average values of observed heterozygosity and expected heterozygosity were 0.54 and 0.49, respectively. The Nei’s gene diversity varied from 0.12 to 0.69, with a mean value of 0.48. Resulting of the markers testing showed that the identified genome-wide SSRs were useful in rapeseed genetic studies, including genetic diversity, QTL mapping and marker-assisted selection for breeding.

A redox active polymer network film containing donor–node–acceptor (D–n–A) units was prepared by using the electropolymerization (EP) of the precursor (4Cz–4Cl–PBI). The polymer film was characterized by the UV–vis absorption, FT-IR, SEM, XRD and electrochemical techniques. The precursor contains phenyl connected two carbazoles (D) linked by the two sp3 N-nodes on both sides of a tetrachloro-substituted PBI (A). The two N-nodes block the conjugation between D and A units, resulting in an independent redox activity (from D and A) and doping behaviors. This novel concept of the D–n–A polymer effectively increases the conductivity and stability of the n-doped state. The EP film can be prepared on ITO and flexible electrodes with large area, smooth surface morphology, controllable thickness, and nanoporous structure. Notably, the polymer network film showed ambipolar doping characteristics, with high capacitance (both n- and p-doped states). These properties are very suitable to construct ambipolar electrodes...

Pyridal[2,1,3]thiadiazole (PT) is an analogue of benzo[1,2,5]thiadiazole (BT), which is a common acceptor in charge transfer (CT) chromophores. Compared with BT, PT is more electron-deficient and less sterically hindered. Herein we demonstrate the effect of using PT as proto-acceptor in the design of D–A type NIR emitting materials. The compound p-TPA-PT-CN was synthesized, which combines PT with the donor triphenylamine (TPA) and cyano-substituent (CN), and shows NIR emission at ∼700 nm with a high PL efficiency of 0.3 in both solution and solid state. The strong D–A interaction within p-TPA-PT-CN results in a low energy charge-transfer state. The pyridine nitrogen of PT reduces the steric hindrance between PT and the adjacent TPA donor segment, resulting in increased planarity and strong mixing (hybridization) of CT and π–π states (HLCT). Such strong mixing contributes towards a higher luminous efficiency. The OLEDs fabricated with p-TPA-PT-CN as the emitting layer exhibited an EQE of 1.47% and Lmax = 640 cd m−2, which are amongst the highest values reported for NIR-OLED devices.

The twist angle and rotation freedom between the donor (D) and acceptor (A) in D–A materials plays an important role in their photophysical properties. Here, the authors select the asymmetric acceptor pyridal[2,1,3]thiadiazole (PT) to construct two D–A isomers (p-TPA-PT and d-TPA-PT) with different twist angle and rotation freedom due to the donor triphenylamine (TPA) proximal or distal to N-atom (pyridyl), as well as a symmetric bis-triphenylamine-substituted compound DTPA-PT for their investigation. On the basis of experimental and theoretical analysis, the authors have explained how the difference in twist-angle and freedom of rotation affects the photophysical properties of these materials. The p-TPA-PT has small twist angles with a relative large kr, however, the more freedom of rotation of the D–A bond causes larger knr, which is comparable to the kr, and thus a lower photoluminescence (PL) efficiency is obtained in the doped film. Although the d-TPA-PT has relative large twist angles with low kr, the suppressed rotation of the DA bond significantly reduces knr, resulting in more competitive kr when compared with the p-TPA-PT, consequently relatively higher PL efficiency is observed. The DTPA-PT, combination of p-TPA-PT and d-TPA-PT, shows highest kr, much larger than its knr, therefore shows highest PL efficiency. As a result, the DTPA-PT based organic light emitting diode (OLED) shows beautiful deep-red emission, maximum external quantum efficiency of 3.87%, Lmax = 12 000 cd m−2, which is among the best deep-red OLED devices.

Different compared to optoelectronics based on electron transformation, ion transport plays important roles in electrochromic applications. To improve ion transport properties, a novel poly(3,4-dioxythiophene) dimer (PM-BTE) was electropolymerized by an alkoxyl connected 3,4-dioxythiophene dimer and fully characterized. The PM-BTE soft nano-networks exhibit excellent electrochromic properties, which show reversible oxidization and reduction accompanied from dark blue to brown yellow, have an optical contrast ΔT = 38.8%, coloration efficiencies of 263.5 cm2 C−1 at 900 nm, low switching voltages and a response of time 1.8 s, with excellent stability and colour persistence. The electrochromic performance is well promoted compared with that of PEDOT (one-fold in coloration efficiency and 60% in response time for the best), which was found to be a result of the as formed PM-BTE films showing a soft nano-network and providing a compatible ion transport channel.

Table S1. Primers for expression analysis of qRT-PCR, cDNA cloning of HTT2, and identification of HPT gene in transgenic plants. (DOCX 20 kb)

An innovative approach for sensitive and simple electrochemical detection of non-electroactive organophosphorus pesticides (OPs) was described in this report. The novel strategy emphasized the fabrication of an oxime-based sensor via attaching pralidoxime (PAM) on graphene quantum dots (GQDs) modified glassy carbon electrode. The introduction of GQDs significantly increased the effective electrode area, and then enlarged the immobilization quantity of PAM. Thus, the oxidation current of PAM was obviously increased. Relying on the nucleophilic substitution reaction between oxime and OPs, fenthion was detected using PAM as the electroactive probe. Under optimum conditions, the difference of oxidation current of PAM was proportional to fenthion concentration over the range from 1.0 × 10 −11 M to 5.0 × 10 −7 M with a detection limit of 6.8 × 10 −12 M (S/N = 3). Moreover, the favorable detection performance in water and soil samples heralded the promising applications in on-site OPs detection.

microRNAs (miRNAs) are a class of newly identified, noncoding, small RNA molecules that negatively regulate gene expression. Many miRNAs are reportedly involved in plant growth, development and stress response processes. However, their roles in the sexual reproduction mechanisms in flowering plants remain unknown. Pollen development is an important process in the life cycle of a flowering plant, and it is closely related to the yield and quality of crop seeds. This study aimed to identify miRNAs involved in pollen development. A microarray assay was conducted using the known complementary sequences of plant miRNAs as probes on inflorescences of a sterile male line (Bcajh97-01A) and a fertile male line (Bcajh97-01B) of the Brassica campestris ssp. chinensis cv. ‘Aijiaohuang’ genic male sterility sister line system (Bcajh97-01A/B). The results showed that 44 miRNAs were differently expressed in the two lines. Of these, 15 had over 1.5-fold changes in their transcript levels, with 9 upregulated and 6 downregulated miRNAs in inflorescences of ‘Bcajh97-01A’ sterile line plants. We then focused on 3 of these 15 miRNAs (miR158, miR168 and miR172). Through computational methods, 13 family members were predicted for these 3 miRNAs and 22 genes were predicted to be their candidate target genes. By using 5’ modified RACE, 2 target genes of miR168 and 5 target genes of miR172 were identified. Then, qRT-PCR was applied to verify the existence and expression patterns of the 3 miRNAs in the flower buds at five developmental stages. The results were generally consistent with those of the microarray. Thus, this study may give a valuable clue for further exploring the miRNA group that may function during pollen development. Electronic Supplementary Material Supplementary material is available for this article at 10.2478/s11658-013-0097-9 and is accessible for authorized users.

Fertilization is controlled by a complex gene regulatory network. To study the fertilization mechanism, we determined time courses of the four developmental stages of fertilization in Chinese cabbage pak-choi (Brassica campestris subsp. chinensis) by cytological observation. We then used the Arabidopsis ATH1 microarray to characterize the gene expression profiles of pollinated and unpollinated pistils in B. campestris subsp. chinensis. The result showed 44 up-regulated genes and 33 down-regulated genes in pollinated pistils compared with unpollinated pistils. Gene ontology analysis identified 20% of the up-regulated genes as belonging to the category of cell wall metabolism. We compared the up-regulated genes in pollinated pistils with previously identified pollen development related genes. Ten genes were found to be in common, which were termed as continuously expressed genes, in the two processes in the present article. Their expression patterns during pollen development and fertilization processes were then verified by RT–PCR. One of the continuously expressed genes, the homologous gene of At3g01270 in B. campestris subsp. chinensis, was confirmed as specifically expressed in microspores and pollinated pistils by using in situ hybridization. The potential biological functions of the other continuously expressed genes were also discussed.

The present paper deals with the CgA level during metastasis linked with Capacitance relaxation phenomenon in cancer cell. CgA co-stored and correlated by exocytosis with catecholamines is a precursor to peptides that exert feedback regulatory control on catecholamine secretion. It is to be noted that CgA was the most sensitive marker for detecting patients with tumor angiogenesis. The progressive rise in CgA increases with the tumor size and this fact has been correlated with the Capacitance relaxation phenomenon (T. K. Basak, US patent No. 5691178, 1997) in different stages. The experimental results of Capacitance relaxation phenomenon were given as inputs to a model for correlation with the CgA level. This model is a control system model, the output of which is the CgA level. It is to be noted that the model is simulated in MATLAB. The expression of tumorogenisis in prostate and liver is also linked to Capacitance relaxation phenomenon in respect of its correlation with the CgA level.

Brassica campestris pectate lyase-like 9 (BcPLL9) was previously identified as a differentially expressed gene both in buds during late pollen developmental stage and in pistils during fertilization in Chinese cabbage. To characterize the gene's function, antisense-RNA lines of BcPLL9 (bcpll9) were constructed in Chinese cabbage. Self- and cross-fertilization experiments harvested half seed yields when bcpll9 lines were used as pollen donors. In vivo and in vitro pollen germination assays showed that nearly half of the pollen tubes in bcpll9 were irregular with shorter length and uneven surface. Aniline blue staining identified abnormal accumulation of a specific bright blue unknown material in the bcpll9 pollen portion. Scanning electron microscopy observation verified the abnormal outthrust material to be near the pollen germinal furrows. Transmission electron microscopy observation revealed the internal endintine layer was overdeveloped and predominantly occupied the intine. This abnormally formed intine likely induced the wavy structure and growth arrest of the pollen tube in half of the bcpll9 pollen grains, which resulted in less seed yields. Collectively, this study presented a novel PLL gene that has an important function in B. campestris intine formation.

Background microRNAs (miRNAs) are endogenous, noncoding, small RNAs that have essential regulatory functions in plant growth, development, and stress response processes. However, limited information is available about their functions in sexual reproduction of flowering plants. Pollen development is an important process in the life cycle of a flowering plant and is a major factor that affects the yield and quality of crop seeds. Results This study aims to identify miRNAs involved in pollen development. Two independent small RNA libraries were constructed from the flower buds of the male sterile line (Bcajh97-01A) and male fertile line (Bcajh97-01B) of Brassica campestris ssp. chinensis. The libraries were subjected to high-throughput sequencing by using the Illumina Solexa system. Eight novel miRNAs on the other arm of known pre-miRNAs, 54 new conserved miRNAs, and 8 novel miRNA members were identified. Twenty-five pairs of novel miRNA/miRNA* were found. Among all the identified miRNAs, 18 differentially expressed miRNAs with over two-fold change between flower buds of male sterile line (Bcajh97-01A) and male fertile line (Bcajh97-01B) were identified. qRT-PCR analysis revealed that most of the differentially expressed miRNAs were preferentially expressed in flower buds of the male fertile line (Bcajh97-01B). Degradome analysis showed that a total of 15 genes were predicted to be the targets of seven miRNAs. Conclusions Our findings provide an overview of potential miRNAs involved in pollen development and interactions between miRNAs and their corresponding targets, which may provide important clues on the function of miRNAs in pollen development.