Dataset Information

Transcriptome Analysis and Ultrastructure Observation Reveal that Hawthorn Fruit Softening Is due to Cellulose/Hemicellulose Degradation.

ABSTRACT: Softening, a common phenomenon in many fruits, is a well coordinated and genetically determined process. However, the process of flesh softening during ripening has rarely been described in hawthorn. In this study, we found that 'Ruanrou Shanlihong 3 Hao' fruits became softer during ripening, whereas 'Qiu JinXing' fruits remained hard. At late developmental stages, the firmness of 'Ruanrou Shanlihong 3 Hao' fruits rapidly declined, and that of 'Qiu JinXing' fruits remained essentially unchanged. According to transmission electron microscopy, the middle lamella of 'Qiu JinXing' and 'Ruanrou Shanlihong 3 Hao' fruit flesh was largely degraded as the fruits matured. Microfilaments in 'Qiu JinXing' flesh were arranged close together and were deep in color, whereas those in 'Ruanrou Shanlihong 3 Hao' fruit flesh were arranged loosely, partially degraded and light in color. RNA-Seq analysis yielded approximately 46.72 Gb of clean data and 72,837 unigenes. Galactose metabolism and pentose and glucuronate interconversions are involved in cell wall metabolism, play an important role in hawthorn texture. We identified 85 unigenes related to the cell wall between hard- and soft-fleshed hawthorn fruits. Based on data analysis and real-time PCR, we suggest that ?-GAL and PE4 have important functions in early fruit softening. The genes Ffase, Gns,?-GAL, PE63, XTH, and CWP, which are involved in cell wall degradation, are responsible for the different textures of hawthorn fruits. Thus, we hypothesize that the different textures of 'Qiu JinXing' and 'Ruanrou Shanlihong 3 Hao' fruits at maturity mainly result from cellulose/hemicelluloses degradation rather than from lamella degradation. Overall, we propose that different types of hydrolytic enzymes in cells interact to degrade the cell wall, resulting in ultramicroscopic Structure changes in the cell wall and, consequently, fruit softening. These results provide fundamental insight regarding the mechanisms by which hawthorn fruits acquire different textures and also lay a solid foundation for further research.

SUBMITTER: Xu J

PROVIDER: S-EPMC5063854 | biostudies-literature | 2016

REPOSITORIES: biostudies-literature

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Transcriptome Analysis and Ultrastructure Observation Reveal that Hawthorn Fruit Softening Is due to Cellulose/Hemicellulose Degradation.

Xu Jiayu J Zhao Yuhui Y Zhang Xiao X Zhang Lijie L Hou Yali Y Dong Wenxuan W

Frontiers in plant science 20161014

Softening, a common phenomenon in many fruits, is a well coordinated and genetically determined process. However, the process of flesh softening during ripening has rarely been described in hawthorn. In this study, we found that 'Ruanrou Shanlihong 3 Hao' fruits became softer during ripening, whereas 'Qiu JinXing' fruits remained hard. At late developmental stages, the firmness of 'Ruanrou Shanlihong 3 Hao' fruits rapidly declined, and that of 'Qiu JinXing' fruits remained essentially unchanged. ...[more]

PMID: 27790234

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Project description:BackgroundCellulose is the most abundant organic polymer mainly produced by plants in nature. It is insoluble and highly resistant to enzymatic hydrolysis. Cellulolytic microorganisms that are capable of producing a battery of related enzymes play an important role in recycling cellulose-rich plant biomass. Effective cellulose degradation by multiple synergic microorganisms has been observed within a defined microbial consortium in the lab culture. Metagenomic analysis may enable us to understand how microbes cooperate in cellulose degradation in a more complex microbial free-living ecosystem in nature.ResultsHere we investigated a typical cellulose-rich and alkaline niche where constituent microbes survive through inter-genera cooperation in cellulose utilization. The niche has been generated in an ancient paper-making plant, which has served as an isolated habitat for over 7 centuries. Combined amplicon-based sequencing of 16S rRNA genes and metagenomic sequencing, our analyses showed a microbial composition with 6 dominant genera including Cloacibacterium, Paludibacter, Exiguobacterium, Acetivibrio, Tolumonas, and Clostridium in this cellulose-rich niche; the composition is distinct from other cellulose-rich niches including a modern paper mill, bamboo soil, wild giant panda guts, and termite hindguts. In total, 11,676 genes of 96 glucoside hydrolase (GH) families, as well as 1,744 genes of carbohydrate transporters were identified, and modeling analysis of two representative genes suggested that these glucoside hydrolases likely evolved to adapt to alkaline environments. Further reconstruction of the microbial draft genomes by binning the assembled contigs predicted a mutualistic interaction between the dominant microbes regarding the cellulolytic process in the niche, with Paludibacter and Clostridium acting as helpers that produce endoglucanases, and Cloacibacterium, Exiguobacterium, Acetivibrio, and Tolumonas being beneficiaries that cross-feed on the cellodextrins by oligosaccharide uptake.ConclusionThe analysis of the key genes involved in cellulose degradation and reconstruction of the microbial draft genomes by binning the assembled contigs predicted a mutualistic interaction based on public goods regarding the cellulolytic process in the niche, suggesting that in the studied microbial consortium, free-living bacteria likely survive on each other by acquisition and exchange of metabolites. Knowledge gained from this study will facilitate the design of complex microbial communities with a better performance in industrial bioprocesses.

Project description:BACKGROUND:The search for new enzymes and microbial strains to degrade plant biomass is one of the most important strategies for improving the conversion processes in the production of environment-friendly chemicals and biofuels. In this study, we report a new Paenibacillus isolate, O199, which showed the highest efficiency for cellulose deconstruction in a screen of environmental isolates. Here, we provide a detailed description of the complex multi-component O199 enzymatic system involved in the degradation of lignocellulose. RESULTS:We examined the genome and the proteome of O199 grown on complex lignocellulose (wheat straw) and on microcrystalline cellulose. The genome contained 476 genes with domains assigned to carbohydrate-active enzyme (CAZyme) families, including 100 genes coding for glycosyl hydrolases (GHs) putatively involved in cellulose and hemicellulose degradation. Moreover, 31 % of these CAZymes were expressed on cellulose and 29 % on wheat straw. Proteomic analyses also revealed a complex and complete set of enzymes for deconstruction of cellulose (at least 22 proteins, including 4 endocellulases, 2 exocellulases, 2 cellobiohydrolases and 2 ?-glucosidases) and hemicellulose (at least 28 proteins, including 5 endoxylanases, 1 ?-xylosidase, 2 xyloglucanases, 2 endomannanases, 2 licheninases and 1 endo-?-1,3(4)-glucanase). Most of these proteins were secreted extracellularly and had numerous carbohydrate-binding domains (CBMs). In addition, O199 also secreted a high number of substrate-binding proteins (SBPs), including at least 42 proteins binding carbohydrates. Interestingly, both plant lignocellulose and crystalline cellulose triggered the production of a wide array of hydrolytic proteins, including cellulases, hemicellulases, and other GHs. CONCLUSIONS:Our data provide an in-depth analysis of the complex and complete set of enzymes and accessory non-catalytic proteins-GHs, CBMs, transporters, and SBPs-implicated in the high cellulolytic capacity shown by this bacterial strain. The large diversity of hydrolytic enzymes and the extracellular secretion of most of them supports the use of Paenibacillus O199 as a candidate for second-generation technologies using paper or lignocellulosic agricultural wastes.

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Transcriptome Analysis and Ultrastructure Observation Reveal that Hawthorn Fruit Softening Is due to Cellulose/Hemicellulose Degradation.

Publications

Transcriptome Analysis and Ultrastructure Observation Reveal that Hawthorn Fruit Softening Is due to Cellulose/Hemicellulose Degradation.

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