Astaxanthin production by Phaffia rhodozyma fermentation of cassava residues substrate

Cassava residues as main materials were fermented with Phaffia rhodozyma to produce astaxanthin.  Using the Box-Behnken design, the effects of sugar content, initial pH and nitrogen content were studied with the yield of astaxanthin as response value, which was evaluated to optimize the fermentation conditions of astaxanthin production.  The optimal fermentation conditions have been reached by the study: sugar content was 40 g/L, the initial pH was at 4 and nitrogen content was 8 g/L.  By validation test, the astaxanthin yield under the optimal condition, which was basically corresponded to the model prediction, was 96.83%.Keywords: astaxanthin, cassava recidues, Phaffia rhodozym

The analysis of candidate genes and loci involved with carotenoid metabolism in cassava (Manihot esculenta Crantz) using SLAF-seq

Carotenoids in cassava storage roots play important roles in benefiting people’s health in the tropics because they provide essential nutrients and antioxidants. Although the related genes and loci associated with carotenoid metabolism in many species are well reported, in cassava they are poorly understood. In the present study, GWAS base on SLAF-seq was used in detecting the related genes and loci correlated to carotenoid contents in 98 accessions from a cassava F1 mapping population. The 98 accessions were divided into four subgroups. On the basis of general linear and compressed linear models, 144 genes were detected by selective sweep analysis, and 84 SNPs and 694 genes were detected by association mapping, in which Manes.04G164700 (XanDH) and Manes.11G105300 (AAO) were probably involved in the downstream pathway of carotenoid metabolism, and their expressions in six cassava genotypes were confirmed. Our results will be useful in yellow-root cassava variety improvement and provide the most effective and sustainable approach to maximize the nutritional and health benefits of carotenoid to a large number of populations

Proteome characterization of cassava (Manihot esculenta Crantz) somatic embryos, plantlets and tuberous roots

<p>Abstract</p> <p>Background</p> <p>Proteomics is increasingly becoming an important tool for the study of many different aspects of plant functions, such as investigating the molecular processes underlying in plant physiology, development, differentiation and their interaction with the environments. To investigate the cassava (<it>Manihot esculenta </it>Crantz) proteome, we extracted proteins from somatic embryos, plantlets and tuberous roots of cultivar SC8 and separated them by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE).</p> <p>Results</p> <p>Analysis by liquid chromatography-electrospray ionisation-tandem mass spectrometry (LC-ESI-MS/MS) yielded a total of 383 proteins including isoforms, classified into 14 functional groups. The majority of these were carbohydrate and energy metabolism associated proteins (27.2%), followed by those involved in protein biosynthesis (14.4%). Subsequent analysis has revealed that 54, 59, 74 and 102 identified proteins are unique to the somatic embryos, shoots, adventitious roots and tuberous roots, respectively. Some of these proteins may serve as signatures for the physiological and developmental stages of somatic embryos, shoots, adventitious roots and tuberous root. Western blotting results have shown high expression levels of Rubisco in shoots and its absence in the somatic embryos. In addition, high-level expression of α-tubulin was found in tuberous roots, and a low-level one in somatic embryos. This extensive study effectively provides a huge data set of dynamic protein-related information to better understand the molecular basis underlying cassava growth, development, and physiological functions.</p> <p>Conclusion</p> <p>This work paves the way towards a comprehensive, system-wide analysis of the cassava. Integration with transcriptomics, metabolomics and other large scale "-omics" data with systems biology approaches can open new avenues towards engineering cassava to enhance yields, improve nutritional value and overcome the problem of post-harvest physiological deterioration.</p

Domestication syndrome is investigated by proteomic analysis between cultivated cassava (Manihot esculenta Crantz) and its wild relatives

Cassava (Manihot esculenta Crantz) wild relatives remain a largely untapped potential for genetic improvement. However, the domestication syndrome phenomena from wild species to cultivated cassava remain poorly understood. The analysis of leaf anatomy and photosynthetic activity showed significantly different between cassava cultivars SC205, SC8 and wild relative M. esculenta ssp. Flabellifolia (W14). The dry matter, starch and amylose contents in the storage roots of cassava cultivars were significantly more than that in wild species. In order to further reveal the differences in photosynthesis and starch accumulation of cultivars and wild species, the globally differential proteins between cassava SC205, SC8 and W14 were analyzed using 2-DE in combination with MALDI-TOF tandem mass spectrometry. A total of 175 and 304 proteins in leaves and storage roots were identified, respectively. Of these, 122 and 127 common proteins in leaves and storage roots were detected in SC205, SC8 and W14, respectively. There were 11, 2 and 2 unique proteins in leaves, as well as 58, 9 and 12 unique proteins in storage roots for W14, SC205 and SC8, respectively, indicating proteomic changes in leaves and storage roots between cultivated cassava and its wild relatives. These proteins and their differential regulation across plants of contrasting leaf morphology, leaf anatomy pattern and photosynthetic related parameters and starch content could contribute to the footprinting of cassava domestication syndrome. We conclude that these global protein data would be of great value to detect the key gene groups related to cassava selection in the domestication syndrome phenomena

Cassava genome from a wild ancestor to cultivated varieties

Cassava is a major tropical food crop in the Euphorbiaceae family that has high carbohydrate production potential and adaptability to diverse environments. Here we present the draft genome sequences of a wild ancestor and a domesticated variety of cassava and comparative analyses with a partial inbred line. We identify 1,584 and 1,678 gene models specific to the wild and domesticated varieties, respectively, and discover high heterozygosity and millions of single-nucleotide variations. Our analyses reveal that genes involved in photosynthesis, starch accumulation and abiotic stresses have been positively selected, whereas those involved in cell wall biosynthesis and secondary metabolism, including cyanogenic glucoside formation, have been negatively selected in the cultivated varieties, reflecting the result of natural selection and domestication. Differences in microRNA genes and retrotransposon regulation could partly explain an increased carbon flux towards starch accumulation and reduced cyanogenic glucoside accumulation in domesticated cassava. These results may contribute to genetic improvement of cassava through better understanding of its biology

Methods and strategies for cassava technology transfer in China

This paper describes the general situation and the existing problems of the extension of new cassava varieties, agronomic practices as well as processing technologies under the conditions of highly intensive agriculture in China. Cassava has been cultivated in China for over 170 years. Its production evolved from a small-scale backyard crop to large-scale commercial production; from a basic food crop to an upland cash crop used for animal feeding and industrial processing, while cropping systems gradually changed from predominantly monocropping to intercropping and crop rotations. However, the area under cassava production is decreasing due to the development of highly intensive agriculture on flat land and a policy of reforestation on steep slopes. Therefore, it is very important to improve the extension of new cassava technologies so as to increase yields and the production value of cassava. Presently, several research institutes, such as SCATC, UCRI and GSCRI, have cassava breeding programs. Since the 1960s SCATC has collected, evaluated, propagated and recommended some good varieties, such as SC205 and SC201, for release and promotion among cassava farmers in southern China. Recently, a national cassava cooperation network, led by research institutes, has been established with the objective of introducing, propagating, demonstrating and testing of promising breeding lines in regional trials. This is a combination of research and production, simultaneously testing, demonstrating and promoting good varieties with the help of agricultural extension units and financed by agricultural authorities in the government. Two new high-yielding varieties, namely SC124 and Nanzhi-188 (the latter introduced from CIAT in tissue culture), have recently been released and are now grown on about 26,000 ha with an average yield of 30-40% over previous varieties, which represents an increase in income of 12-15 million yuan. Similarly, the intercropping or rotational cropping of cassava with pasture species, such as Stylosanthes 184, increased gross income 23-43% and reduced soil erosion by 14-27%. Research on cassava further-processing, conducted by the Guangxi Nanning Cassava Technical Development Centre, has also contributed greatly to increase the value of cassava-based products and to expand marketing channels, both at home and abroad

Recent progress in cassava varietal improvement in China

The paper discusses the research progress mainly for the period of 1990-1993. There are three institutions, SCATC, UCRI and GSCRI, which are systematically working on cassava breeding in China. Since the principal constraint to cassava varietal improvement is the lack of genetic variability, the main approach currently used is the evaluation and selection of hybrid seeds introduced from CIAT/Colombia and from the Thai-CIAT program. In the past few years, remarkable progress has been made in these three institutions, mainly as follows: 1) At SCATC, advanced clones continue to show promising results in comparison with the respectable local control (SC205). Many high-yielding clones were identified in preliminary trials, in which Thai-CIAT material showed a clearly superior performance. 2) At UCRI of the Guangdong Academy of Agric. Sciences, very convincing yield data of a pre-released clone (ZM8002) were obtained from four years of regional trials and another three years of demonstration trials. In addition, many clearly superior new clones were selected from CIAT seed material in a replicated yield trial, nearly doubling the yields of ZM48002 or SC201. Two advanced clones, selected from locally hybridized seeds, showed a high yield potential. 3) At GSCRI, several clones selected from ClAT-introduced seeds showed for the first time a clearly superior yield and dry matter content over local controls in 1992. 4) Additional genetic variability was obtained at SCATC through induced mutations using colchicine treatments. These mutants are presently being evaluate

Farmer participatory research in cassava soil management and varietal dissemination in China

This paper mainly describes the objectives of the FPR project, the results of the RRA that was conducted in Hainan and the demonstration plots at CATAS, as well as the demonstration and FPR trials at the pilot sites (especially in Kongba village of Baisha county). The major existing problems and suggestions to improve the FPR trials in the future are also presented

Progress in cassava breeding at the Chinese Academy of Tropical and Agric. Sciences (CATAS)

During the past 16 years the Chinese Academy of Tropical and Agricultural Sciences (CATAS) has made good progress in developing improved cassava varieties for China. Several improved varieties have been released in south China, of which cv. SC124, with high yield and good cold resistance, is already being planted on a large scale, mainly in Guangxi and Yunnan provinces. SC8002, which is characterized by a high yield potential and tolerance to cold, has mainly been released in Guangdong province, while SC8013, with high yield and good wind resistance, is being multiplied for planting in the typhoon affected areas of Hainan and Zhanjiang district of Guangdong. The release of these new varieties will improve the present situation of dependence on only two varieties, and will promote varietal comparisons, as well as stimulate the development of cassava production in China. In recent years, a large F population and its progeny clones have been produced from true seeds, which were mainly introduced from CIAT/Colombia and from the Thai-CIAT program. Up to 1995, a series of breeding materials with different characters have been evaluated and selected; out of these, three new varieties have been released, more than 30 accessions have been used as cross parents, and 15 promising clones have been recommended for testing in Regional Trials. In 1996, 316 clones were tested at the Single-row Trial, 63 clones were further evaluated at the Preliminary Yield Trial, and 54 clones were included in the Advanced Yield Trials. Most of the clones in the Regional Trial and the Advanced Yield Trial were characterized by high yield and high dry matter content (especially clones OMR33-10-4 and OMR34-1 1-3 have very high dry matter content); their performance at the later stages is closely being watched. Also, some good clones were selected from the Preliminary Yield Trial in 1995/96, such as ZM9315, ZM93255, ZM9317,ZM93236 etc., andOMR36-63-6,OMR36-40-9,OMR36-05-9 etc. from the Single-row Trial; these showed significantly higher yields compared with the check variety, SC205, while their root dry matter contents were higher than 40%, the harvest indices were over 0.62 and they had good wind resistance. High-yield, high dry matter content and good wind resistance are still our major objectives in cassava breeding. From our experience we are convinced that it is impossible to make any major breakthrough in our breeding program by just using our native genetic resources. There are two ways for us to realize our objectives in the future: 1) selection from the hybridizations between our local germplasm and those from CIAT/Colombia or the Thai-CIAT program, such as ZM9036, ZM8803, ZM9057 etc.; and 2) the comprehensive evaluation and direct selection of the seed materials introduced from CIAT/Colombia or the Thai-CIAT program. While the importance of the former scheme is increasing, up to now, many of the good clones with high yield, high dry matter content and high harvest index were selected from this latter source. As such, the materials introduced from CIAT/Colombia or the Thai-CIAT program and their hybrids with the local genetic materials are playing an important role in cassava varietal improvement in China