Adsorption behaviors of novel betaines on the wettability of the quartz surface.

The contact angle measurements for the aqueous solutions of two pairs of zwitterions on quartz surfaces have been investigated by the sessile drop analysis. The different physicochemical parameters such as the critical micelle concentration (CMC), surface tension, contact angle, surface excess on air-liquid and solid-liquid interfaces and work of adhesion have been estimated. The obtained results show that the contact angle of surfactants such as alkyl carboxylbetaine (ACB) and ditolyl substituted alkyl carboxylbetaine (BCB) remains almost constant in a wide range of surfactant concentration and increases gradually above CMC, which are quite different from traditional surfactants reported in the literature. Surfactants with bigger polar groups have a more steric effect on the quartz surface and the contact angle remains relatively unchanged. Moreover, an increase in quartz-liquid interfacial tension (γSL) has been observed due to the adsorption of four zwitterionic surfactants. Especially for ACB and BCB, at the surfactant concentrations higher than 5 × 10(-5) mol L(-1), a moderate increase in the interfacial tension of the quartz-liquid is observed, which suggests that ACB and BCB can form a saturated adsorption film briefly on the quartz surface and then adsorb again. However, the addition of alkyl sulfobetaine (ASB) and ditolyl substituted alkyl sulfobetaine (BSB) after CMC cannot adsorb on the quartz surface again due to the steric effect of bigger polar groups.

The interaction of banana MADS-box protein MuMADS1 and ubiquitin-activating enzyme E-MuUBA in post-harvest banana fruit.

KEY MESSAGE : The interaction of MuMADS1 and MuUBA in banana was reported, which will help us to understand the mechanism of the MADS-box gene in regulating banana fruit development and ripening. The ubiquitin-activating enzyme E1 gene fragment MuUBA was obtained from banana (Musa acuminata L.AAA) fruit by the yeast two-hybrid method using the banana MADS-box gene MuMADS1 as bait and 2-day post-harvest banana fruit cDNA library as prey. MuMADS1 interacted with MuUBA. The interaction of MuMADS1 and MuUBA in vivo was further proved by bimolecular fluorescence complementation assay. Real-time quantitative PCR evaluation of MuMADS1 and MuUBA expression patterns in banana showed that they are highly expressed in the ovule 4 stage, but present in low levels in the stem, which suggests a simultaneously differential expression action exists for both MuMADS1 and MuUBA in different tissues and developmental fruits. MuMADS1 and MuUBA expression was highly stimulated by exogenous ethylene and suppressed by 1-methylcyclopropene. These results indicated that MuMADS1 and MuUBA were co-regulated by ethylene and might play an important role in post-harvest banana fruit ripening.

Identification and analysis of lignin biosynthesis genes related to fruit ripening and stress response in banana (Musa acuminata L. AAA group, cv. Cavendish).

Background: Lignin is a key component of the secondary cell wall of plants, providing mechanical support and facilitating water transport as well as having important impact effects in response to a variety of biological and abiotic stresses. Results: In this study, we identified 104 genes from ten enzyme gene families related to lignin biosynthesis in Musa acuminata genome and found the number of MaCOMT gene family was the largest, while MaC3Hs had only two members. MaPALs retained the original members, and the number of Ma4CLs in lignin biosynthesis was significantly less than that of flavonoids. Segmental duplication existed in most gene families, except for MaC3Hs, and tandem duplication was the main way to expand the number of MaCOMTs. Moreover, the expression profiles of lignin biosynthesis genes during fruit development, postharvest ripening stages and under various abiotic and biological stresses were investigated using available RNA-sequencing data to obtain fruit ripening and stress response candidate genes. Finally, a co-expression network of lignin biosynthesis genes was constructed by weighted gene co-expression network analysis to elucidate the lignin biosynthesis genes that might participate in lignin biosynthesis in banana during development and in response to stresses. Conclusion: This study systematically identified the lignin biosynthesis genes in the Musa acuminata genome, providing important candidate genes for further functional analysis. The identification of the major genes involved in lignin biosynthesis in banana provides the basis for the development of strategies to improve new banana varieties tolerant to biological and abiotic stresses with high yield and high quality.

Identification and expression analysis of four 14-3-3 genes during fruit ripening in banana (Musa acuminata L. AAA group, cv. Brazilian).

To investigate the regulation of 14-3-3 proteins in banana (Musa acuminata L. AAA group, cv. Brazilian) fruit postharvest ripening, four cDNAs encoding 14-3-3 proteins were isolated from banana and designated as Ma-14-3-3a, Ma-14-3-3c, Ma-14-3-3e, and Ma-14-3-3i, respectively. Amino acid sequence alignment showed that the four 14-3-3 proteins shared a highly conserved core structure and variable C-terminal as well as N-terminal regions with 14-3-3 proteins from other plant species. Phylogenetic analysis revealed that the four 14-3-3 genes belong to the non-ε groups. They were differentially and specifically expressed in various tissues. Real-time RT-PCR analysis indicated that these four genes function differentially during banana fruit postharvest ripening. Three genes, Ma-14-3-3a, Ma-14-3-3c, and Ma-14-3-3e, were significantly induced by exogenous ethylene treatment. However, gene function differed in naturally ripened fruits. Ethylene could induce Ma-14-3-3c expression during postharvest ripening, but expression patterns of Ma-14-3-3a and Ma-14-3-3e suggest that these two genes appear to be involved in regulating ethylene biosynthesis during fruit ripening. No obvious relationship emerged between Ma-14-3-3i expression in naturally ripened and 1-MCP (1-methylcyclopropene)-treated fruit groups during fruit ripening. These results indicate that the 14-3-3 proteins might be involved in various regulatory processes of banana fruit ripening. Further studies will mainly focus on revealing the detailed biological mechanisms of these four 14-3-3 genes in regulating banana fruit postharvest ripening.

[Research progress on banana functional genomics involved in fruit quality].

Banana is one of the most important tropical fruits and main economical resource for tropical people. Banana quality is always becoming a focus for people to follow with interest. Here, we reviewed recent research progresses on isolation and identification of banana genes involved in fruit quality such as ripening, softening, glycometabolism, and scent, which will help us explore their functions and facilitate banana quality improvement.

[The interaction of MADS-box transcription factors and manipulating fruit development and ripening].

The proteins encoded by MADS-box genes are a large number of transcription factors, which control plant growth and development by forming homo- or hetero-dimers. Here, we reviewed recent researches on the interactions of MADS-box transcription factors and manipulating fruit development and ripening, which will help us to understand the mechanism of MADS-box transcription factors and provide references for further investigating the functions of MADS-box genes on fruit development and ripening.

Physicochemical, functional and emulsion properties of edible protein from avocado (Persea americana Mill.) oil processing by-products.

Avocado (Persea americana) is a tropical fruit that has drawn great interest its oil for foods and cosmetic industries; however, avocado oil processing by-product is a potential source of edible protein. Herein, edible protein was prepared from defatted avocado meal, and it's physicochemical, functional and emulsion properties were investigated. The avocado protein showed U-shaped exhibiting strong effect of pH, and a minimum solubility being observed at pH 4.5, confirming the isoelectric point of avocado protein. Nutritionally, the avocado protein contains all the essential amino acids. Avocado protein provided higher water and oil absorption capacities, higher radical scavenging capacity but lower in-vitro digestibility compared with soy protein. Furthermore, the avocado protein as emulsifier afforded a stability oil-in-water emulsion system, resulting in a greater emulsifying stability than that of soy protein. The present results highlight the potential source of edible protein from avocado oil processing by-products for functional food ingredients.

Comparison of physicochemical properties and in vitro digestibility of starches from seven banana cultivars in China.

Lots of bananas were wasted before commercialization. It is necessary to search potential industrial applications of banana. In the present study, starches from seven banana cultivars (labeled as A-G) were isolated and then characterized. These starches presented different and irregular shapes, such as sphere, long spheroid and polygonal granules. The distribution of size and analyses of average molecular weight showed more small granules in samples B, D, F and G than other samples. The amylose content varied from 22.59% to 38.40%. The crystal types of these starches were a mixture of B-type and C-type, and the relative crystallinity varied greatly. The differential scanning calorimetry (DSC) results showed that the onset temperature of gelatinization increased as follows: A < B < E < C ≈ D < F. The maximum viscosity of banana starch decreased as follows: G > C > D > F > E = B > A. The in vitro digestibility test showed that the content of resistant starch was very high in banana starches. These results would be useful to the application of those starches in food and nonfood industries.

[Progress on Agrobacterium-mediated transformation of banana].

The development of improved Musa by conventional breeding remains to be a difficult endeavor because of the long generation times, various levels of ploidy, sterility of most edible cultivars and limited genetic variability. Therefore, genetic engineering may offer an alternative method for crop enhancement. The transformation system mediated by Agrobacterium tumefaciens has been used successfully to transform banana during the past 10 years. This article reviews recent progresses on transformation of banana mediated by Agrobacterium tumefaciens and summarizes the factors affecting transformation efficiency. Existing problems and its prospects are briefly discussed.

[Construction of a plant effective expression vector containing the gene of hepatitis B virus surface antigen].

OBJECTIVE: To construct a plant effective expression vector driven by a fruit specific promoter for the expression of hepatitis B virus surface antigen (HBsAg), to further improve the expression of exogenous gene in plant, and to prepare for the development of an effective anti-hepatitis vaccine. METHODS: Tomato fruit-specific promoters' gene 2A12 and E8 were respectively introduced to pBPFOmega7 to form pB2A12 and pBE8. The DNA fragment containing HBsAg-s gene from plasmid YEP-HBs was inserted respectively into pB2A12 and pBE8 to form pB2A12-HBs and pBE8-HBs. The fragment containing "p35S+2A12+Omega+HBsAg-s+Tnos" of the pB2A12-HBs was sub-cloned into plasmid pCAMBIA1301 to yield the reconstructed plant binary expression plasmid pCAM2A12-HBs, and the fragment containing "p35S+E8+Omega+HBsAg-s+Tnos" of the pBE8-HBs was sub-cloned into plasmid pCAMBIA1301 to yield the plasmid pCAME8-HBs. The inserted gene HBsAg and fruit-specific promoters in the reconstructed plant binary expression vectors were confirmed by sequencing. Then, pCAM2A12-HBs and pCAME8-HBs were directly introduced into Agrobacterium tumefaciens strain EHA105. RESULTS: Digestion with restriction enzymes proved that all recombinant vectors had the inserts with expected length of the target fragments, and the sequencing results were confirmed correct. CONCLUSION: In this study, plant expression vector containing HBsAg gene driven by fruit specific promoter and CaMV35s promoter was successfully constructed.

Cloning and developmental and tissue-specific expression of banana (Musa acuminate AAA) lectin gene.

A cDNA encoding banana lectin (BanLec) was obtained by using RT-PCR from banana fruit and sequenced. Comparison of this cDNA sequence with the sequence of BanLec gene registered in GenBank (Accession No. AF001527) showed that both sequences shared high similarity with only nine nucleotieds and four amino acids difference. RT-PCR analysis of the expression patterns of BanLec gene in different tissues and different fruit ripening stages of banana suggested that this cDNA not only expressed specifically in fruit but also expressed developmentally during fruit ripening. Relative quantification of expression level of BanLec gene in different tissues and different ripening stages were carried out by using computer software.

Cloning of an ADP-ribosylation factor gene from banana (Musa acuminata) and its expression patterns in postharvest ripening fruit.

A full-length cDNA encoding an ADP-ribosylation factor (ARF) from banana (Musa acuminata) fruit was cloned and named MaArf. It contains an open reading frame encoding a 181-amino-acid polypeptide. Sequence analysis showed that MaArf shared high similarity with ARF of other plant species. The genomic sequence of MaArf was also obtained using polymerase chain reaction (PCR). Sequence analysis showed that MaArf was a split gene containing five exons and four introns in genomic DNA. Reverse-transcriptase PCR was used to analyze the spatial expression of MaArf. The results showed that MaArf was expressed in all the organs examined: root, rhizome, leaf, flower and fruit. Real-time quantitative PCR was used to explore expression patterns of MaArf in postharvest banana. There was differential expression of MaArf associated with ethylene biosynthesis. In naturally ripened banana, expression of MaArf was in accordance with ethylene biosynthesis. However, in 1-methylcyclopropene-treated banana, the expression of MaArf was inhibited and changed little. When treated with ethylene, MaArf expression in banana fruit significantly increased in accordance with ethylene biosynthesis; the peak of MaArf was 3 d after harvest, 11 d earlier than for naturally ripened banana fruits. These results suggest that MaArf is induced by ethylene in regulating postharvest banana ripening. Finally, subcellular localization assays showed the MaArf protein in the cytoplasm.

Differentially expressed cDNAs at the early stage of banana ripening identified by suppression subtractive hybridization and cDNA microarray.

The banana (Musa acuminate L. AAA group) fruit undergoes a postharvest ripening process, which plays an important role in improving the quality and extending the shelf life of bananas. To manipulate postharvest banana ripening, a better understanding of the mechanism of postharvest ripening is necessary. The isolation of mRNA transcripts encoding proteins associated with the ripening process is a powerful tool for this purpose. To isolate differentially expressed genes at the early stage of postharvest banana ripening, a forward suppression subtractive hybridization (SSH) cDNA library was constructed. SSH was performed with cDNA from banana fruit on the day of harvest as the "driver" and cDNA from banana fruit 2 days postharvest (DPH) as the "tester." A total of 289 clones in the SSH library were sequenced. BLASTX results revealed that 191 cDNAs had significant sequence homologies with known sequences in the NCBI database. Of the 191 cDNAs, 138 were singletons, and 53 belonged to divergent clusters containing 2-8 sequences. The identified cDNAs encoded proteins involved in cellular processes such as: metabolism; protein destination and storage; protein synthesis; signal transduction; transport and intracellular traffic; cell structure, growth, and division; transcription and post-transcription; and disease and defense. To characterize differentially expressed cDNAs in the SSH library, cDNA microarray analysis was conducted. A total of 26 cDNAs in the 2-DPH banana fruit were found to be up-regulated and these results were confirmed by using reverse transcriptase-polymerase chain reaction (RT-PCR). The information generated in this study provides new clues to aid in the understanding of banana ripening.

[Isolation, sequencing analysis and characterization of the promoter of banana lectin gene].

Banana (Musa spp) is one of the most important fruit crops in the world. Banana fruit is an ideal organ for producing foreign pharmaceutical proteins and chemicals by genetic engineering. A perfect promoter driving foreign gene to express strongly and specifically in banana fruit is necessary for that. In order to isolate a banana fruit-specific expressed promoter, a fragment of 702 nt nucleotide sequence upstream 5' of banana lectin (BanLec) gene, which was demonstrated to express specifically in banana fruit previously, was isolated by using chromosomal walking in this study. Bioinformatical analysis of this sequence shows that the sequence contains some typical elements of a promoter. To identify the fruit-specific expression of this promoter, a construct was derived from pBI121, which originally CaMV 35S promoter was replaced by the 702 nt nucleotide sequence, and named as pBIL2. Transformations of pBIL2 to roots, leaves and fruit pieces of banana were carried out by using particle bombardment. The transient expression of gus showed that the gus expressed specifically in banana fruit with a little higher level compared with CaMV 35S. It is the first report that BanLec promoter is a potential fruit-specific expressed promoter which can further be used in transgenes into banana.