The Genomic Tools for Sweetpotato Improvement (GT4SP) Project

This flyer introduces a new four year investment to develop genomic and genetic resources for sweetpotato improvement that has been launched with the goal of establishing a molecular marker-assisted breeding program in sweetpotato. It provides information about the critical scientific constraints to be addressed, the strategies and the partners participating in the project

Distributions, ex situ conservation priorities, and genetic resource potential of crop wild relatives of sweetpotato [Ipomoea batatas (L.) Lam., I. series Batatas]

Crop wild relatives of sweetpotato [Ipomoea batatas (L.) Lam., I. series Batatas] have the potential to contribute to breeding objectives for this important root crop. Uncertainty in regard to species boundaries and their phylogenetic relationships, the limited availability of germplasm with which to perform crosses, and the difficulty of introgression of genes from wild species has constrained their utilization. Here, we compile geographic occurrence data on relevant sweetpotato wild relatives and produce potential distribution models for the species. We then assess the comprehensiveness of ex situ germplasm collections, contextualize these results with research and breeding priorities, and use ecogeographic information to identify species with the potential to contribute desirable agronomic traits. The fourteen species that are considered the closest wild relatives of sweetpotato generally occur from the central United States to Argentina, with richness concentrated in Mesoamerica and in the extreme Southeastern United States. Currently designated species differ among themselves and in comparison to the crop in their adaptations to temperature, precipitation, and edaphic characteristics and most species also show considerable intraspecific variation. With 79% of species identified as high priority for further collecting, we find that these crop genetic resources are highly under-represented in ex situ conservation systems and thus their availability to breeders and researchers is inadequate. We prioritize taxa and specific geographic locations for further collecting in order to improve the completeness of germplasm collections. In concert with enhanced conservation of sweetpotato wild relatives, further taxonomic research, characterization and evaluation of germplasm, and improving the techniques to overcome barriers to introgression with wild species are needed in order to mobilize these genetic resources for crop breeding

Diamondback Moth, Plutella xylostella (L.), control studies on cabbage in St. Kitts

Diamondback moth (DBM) (Plutella xylostella (L.» insecticide efficacy and population dynamics studies were conducted in 51. Kitts 1985 1987. Experiment station and "on-farm" trials were conducted in addition to monitoring small farmers cabbage crops for DBM and Apanteles plutellae population levels. Pennethrin, Bacillus' thuringiensis (Berliner), and pirimiphos-methyl, controlled DaM adequately. Peaks in A. plutellae parasitism coincided with a predominance of 4th instar larvae. The presence of high parasite populations delayed the time to first spray. A relative growth rate analysis of DBM populations indicated that growth rates are correlated to percent A. plutellae parasitism. It is hypothesized that parasitism levels exceeding 25-35% may control DBM populations

Sweetpotato (Ipomoea batatas L.).

Sweet potato has traditionally been viewed as a “poor person’s crop” or “orphan crop,” and it has attracted limited attention compared to other staple crops. However, during the last decade, this perception has changed, and it is widely acknowledged that sweet potato has great potential to contribute to the alleviation of malnutrition and hunger in the developing world. Orange-fleshed sweet potato, in particular, with its high provitamin A content, has become a prominent example of the effectiveness of biofortified staple crops to combat vitamin A deficiency. Similarly, increasing awareness of the nutritional value of sweet potato is driving consumer demand among health-conscious consumers globally, and its potential use in a wide range of value-added human and animal products is widely recognized. As the public and private sectors learn more about the benefits and opportunities of sweet potato, they have invested more in crop improvement; thus our understanding of the importance and potential of the crop is increasing. This chapter covers many aspects of sweet potato improvement with emphasis on the developing world. It includes sections on the history of sweet potato cultivation, general crop biology, the complex genetics and breeding challenges encountered by breeders seeking to improve the crop, crossing and breeding strategies for key traits, germplasm relations and the potential of wild relatives for crop improvement, and a section on seed production and the development of sustainable seed systems. It concludes with a review of advances in molecular genetics and genomics of the crop and the potential uses of these tools for sweet potato improvement

Conventional breeding, marker-assisted selection, genomic selection and inbreeding in clonally propagated crops: a case study for cassava

KEY MESSAGE: Consolidates relevant molecular and phenotypic information on cassava to demonstrate relevance of heterosis, and alternatives to exploit it by integrating different tools. Ideas are useful to other asexually reproduced crops. ABSTRACT: Asexually propagated crops offer the advantage that all genetic effects can be exploited in farmers’ production fields. However, non-additive effects complicate selection because, while influencing the performance of the materials under evaluation, they cannot be transmitted efficiently to the following cycle of selection. Cassava can be used as a model crop for asexually propagated crops because of its diploid nature and the absence of (known) incompatibility effects. New technologies such as genomic selection (GS), use of inbred progenitors based on doubled haploids and induction of flowering can be employed for accelerating genetic gains in cassava. Available information suggests that heterosis, non-additive genetic effects and within-family variation are relatively large for complex traits such as fresh root yield, moderate for dry matter or starch content in the roots, and low for defensive traits (pest and disease resistance) and plant architecture. The present article considers the potential impact of different technologies for maximizing gains for key traits in cassava, and highlights the advantages of integrating them. Exploiting heterosis would be optimized through the implementation of reciprocal recurrent selection. The advantages of using inbred progenitors would allow shifting the current cassava phenotypic recurrent selection method into line improvement, which in turn would allow designing outstanding hybrids rather than finding them by trial and error