Gene cloning of a neutral ceramidase from the sphingolipid metabolic pathway based on transcriptome analysis of Amorphophallus muelleri

Amorphophallus is a perennial herbaceous plant species mainly distributed in the tropics or subtropics of Asia and Africa. It has been used as a traditional medicine for a long time and now is utilized for the pharmaceutical, chemical and agriculture industries as a valued economic crop. Recently, Amorphophallus has attracted tremendous interest because of its high ceramide content. However, the breeding and genome studies are severely limited by the arduous whole genome sequencing of Amorphophallus. In this study, the transcriptome data of A. muelleri was obtained by utilizing the high-throughput Illumina sequencing platform. Based on this information, the majority of the significant genes involved in the proposed sphingolipid metabolic pathway were identified. Then, the full-length neutral ceramidase cDNA was obtained with the help of its candidate transcripts, which were acquired from the transcriptome data. Furthermore, we demonstrated that this neutral ceramidase was a real ceramidase by eukaryotic expression in the yeast double knockout mutant Δypc1 Δydc1, which lacks the ceramidases—dihydroCDase (YDC1p), phytoCDase (YPC1p). In addition, the biochemical characterization of purified A. muelleri ceramidase (AmCDase) exhibited classical Michaelis-Menten kinetics with an optimal activity ranging from pH 6.5 to 8.0. Based on our knowledge, this study is the first to report the related information of the neutral ceramidase in Amorphophallus. All datasets can provide significant information for related studies, such as gene expression, genetic improvement and application on breeding in Amorphophallus.

Temporal and spatial regulation of glucomannan deposition and mobilization in corms of Amorphophallus konjac (Araceae)

PREMISE OF THE STUDY

Konjac glucomannan (KGM), the main biologically active constituent of konjac flour extracted from corms of Amorphophallus konjac (konjac), has potential to be used as a nutraceutical (satiety agent) to combat obesity. Here we present the results of an immunocytochemical investigation of the developmental regulation of the deposition and mobilization of glucomannan in corm tissues of konjac, using an antiheteromannan (mannan/glucomannan) antiserum.

METHODS

The intensity of antibody binding to glucomannan idioblasts at six developmental stages (i.e., dormancy, leaf bud emergence, leaf bud elongation, leaflet emergence, leaf expansion, and shoot senescence) was compared.

KEY RESULTS

A temporally regulated pattern of glucomannan deposition and mobilization within the glucomannan idioblasts was observed. A source-sink transition in the corm was shown to occur after leaflet emergence, prior to complete expansion of the leaves. Our data also suggest that the mobilization of KGM initiates at the periphery of the corm and proceeds inward toward the center of the corm.

CONCLUSIONS

This study represents a significant milestone in our understanding of the mechanisms involved in the physiological and biochemical control of KGM biosynthesis, partitioning, storage, and remobilization. Moreover, this information and the methodology presented provide valuable data for future improvement of the yield and productivity of this important crop.

Lead and other elemental content of normal and Erwinia carotovora infected Amorphallus konjac corms

Amorphallus konjac corms are important agriculture products in Yichang, Hubei Province, China. The Erwinia carotovora infected Amorphallus konjac corms are processed to food as normal corms. The contents of elements and L: -Proline in the normal and infected Amorphallus konjac corms are analyzed for food safety. Even growing in the almost same soil condition, the contents of Pb, Cd, Mn and L: -Proline in infected corms are significantly higher than those of normal corms (show data as suggestion by peers). Our study suggested that the infected corms are not suitable for food purpose.

Histological observations of morphogenesis in petiole derived callus of Amorphophallus rivieri Durieu in vitro

The initiation and development of somatic embryos and organogenic shoots and corm-like structures (CLSs) from petiole-derived calli of Amorphophallus rivieri Durieu were observed histologically. The petioles were cultured on Murashige and Skoog (MS) medium supplemented with 5.37 microM alpha-naphthaleneacetic acid (NAA) and 4.44 microM N(6)-benzylaminopurine (6-BA) for callus induction. The shoot and corm organogenesis occurred from the compact calli when they were transferred to a medium containing 0.54 microM NAA and 4.44 microM 6-BA. A combination of 13.57 microM 2,4-dichlorophenoxyacetic acid (2,4-D) and 8.88 microM 6-BA or 24.18 microM NAA and 6.66 microM 6-BA was optimum for induction of somatic embryos, which failed to produce plantlets because of their structural abnormalities. Shoot regeneration predominantly happened through organogenesis although somatic embryogenesis infrequently occurred. The subepidermal cells of the compact callus converted to competent cells and started divisions, which resulted in formation of the meristemoids. The meristemoid cells continued division to develop into bud primordia. Subepidermal cells could also form the globular structures. Subsequently, these globoids developed into CLSs from which plantlets regenerated during subculture. Meanwhile, the CLSs were capable to form cormels, which could be a promising way for the propagation of A. rivieri.