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

High genetic diversity among and within bitter manioc varieties cultivated in different soil types in Central Amazonia

Although manioc is well adapted to nutrient-poor Oxisols of Amazonia, ethnobotanical observations show that bitter manioc is also frequently cultivated in the highly fertile soils of the floodplains and Amazonian dark earths (ADE) along the middle Madeira River. Because different sets of varieties are grown in each soil type, and there are agronomic similarities between ADE and floodplain varieties, it was hypothesized that varieties grown in ADE and floodplain were more closely related to each other than either is to varieties grown in Oxisols. We tested this hypothesis evaluating the intra-varietal genetic diversity and the genetic relationships among manioc varieties commonly cultivated in Oxisols, ADE and floodplain soils. Genetic results did not agree with ethnobotanical expectation, since the relationships between varieties were variable and most individuals of varieties with the same vernacular name, but grown in ADE and floodplain, were distinct. Although the same vernacular name could not always be associated with genetic similarities, there is still a great amount of variation among the varieties. Many ecological and genetic processes may explain the high genetic diversity and differentiation found for bitter manioc varieties, but all contribute to the maintenance and amplification of genetic diversity within the manioc in Central Amazonia. © 2017, Sociedade Brasileira de Genética

Crops that feed the world: Production and improvement of cassava for food, feed, and industrial uses

Cassava (Manihot esculenta Crantz) is one of the oldest root and tuber crops, used by humans to produce food, feed and beverages. Currently, cassava is produced in more than 100 countries and fulfils the daily caloric demands of millions of people living in tropical America, Africa, and Asia. Its impor-tance as a food security crop is high in Western, Central and Eastern Africa due to its ability to produce reasonable yields (\~10 t/ha) in poor soils and with minimal inputs. Traditionally a famine reserve and a subsistence crop, the status of cassava is now evolving fast as a cash crop and as raw material in the production of starch (and starch based products), energy (bio-ethanol) and livestock feed in the major producing countries. Cassava leaves, which are rich in protein and beta-carotenoids, are also used as a vegetable and forage (fresh or dehydrated meal) in various parts of the world. In recent years, some of the prob-lems in the production of cassava have been increasing infection with cassava mosaic disease (CMD), cassava brown streak dis-ease (CBSD) and cassava bacterial blight (CBB). Inherent post-harvest physiological disorder (PPD) and cyanogenic glycosides (CG) are some of the most prominent challenges for scientists, producers and consumers in the post-production systems. Collaborative research in participatory plant breeding is ongoing at leading international research institutes such as IITA and CIAT to improve crop resistance to virus diseases, reduce PPD and CG, and improve the overall nutritional characteristics. Further re-search should also focus on post-production systems by developing enhanced storage and transportation techniques, mechanisation (peeling, size reduction, drying and dewatering) and improved packaging. Moreover, a robust national policy, market development, and dissemination and extension program are required to realise the full potential of innovations and technologies in cassava production and processing