Adapting clonally propagated crops to climatic changes: a global approach for taro (Colocasia esculenta (L.) Schott)

Clonally propagated crop species are less adaptable to environmental changes than those propagating sexually. DNA studies have shown that in all countries where taro (Colocasia esculenta (L.) Schott) has been introduced clonally its genetic base is narrow. As genetic variation is the most important source of adaptive potential, it appears interesting to attempt to increase genetic and phenotypic diversity to strengthen smallholders’ capacity to adapt to climatic changes. A global experiment, involving 14 countries from America, Africa, Asia and the Pacific was conducted to test this approach. Every country received a set of 50 indexed genotypes in vitro assembling significant genetic diversity. After onstation agronomic evaluation trials, the best genotypes were distributed to farmers for participatory on-farm evaluation. Results indicated that hybrids tolerant to taro leaf blight (TLB, Phytophthora colocasiae Raciborski), developed by Hawaii, Papua New Guinea and Samoa breeding programmes outperformed local cultivars in most locations. However, several elite cultivars from SE Asia, also tolerant to TLB, outperformed improved hybrids in four countries and in one country none of the introductions performed better than the local cultivars. Introduced genotypes were successfully crossed (controlled crossing) with local cultivars and new hybrids were produced. For the first time in the history of Aroids research, seeds were exchanged internationally injecting tremendous allelic diversity in different countries. If climatic changes are going to cause the problems envisaged, then breeding crops with wide genetic diversity appears to be an appropriate approach to overcome the disasters that will otherwise ensue.This research was financially supported by the Europe-Aid project ‘‘Adapting clonally propagated crops to climatic and commercial changes’’ (Grant No. DCI-FOOD/ 2010/230-267 SPC). Thanks are due to the 14 different countries technicians working on research stations and to farmers and their families for their enthusiastic contributioninfo:eu-repo/semantics/publishedVersio

Ovary colonization by Claviceps africana is related to ergot resistance in male-sterile sorghum lines

Ergot, caused by Claviceps africana, has emerged as a serious threat to sorghum hybrid seed production worldwide. In the absence of gene-for-gene-based qualitative resistance in commercial cultivars, varieties with high pollen production that can escape ergot infection are preferred. Recent demonstration of differences in ergot susceptibility among male-sterile lines has indicated the presence of partial resistance. Using chitin-specific fluorescin-isothiocyanate-conjugated wheat germ agglutin and callose-specific aniline blue, this study investigated the process of sorghum ovary colonization by C. africana. Conidia germinated within 24 h after inoculation (a.i.); the pathogen was established in the ovary by 79 h a.i., and at least half of the ovary was converted into sphacelial tissue by 120 h a.i. Changes in fungal cell wall chitin content and strategic callose deposition in the host tissue were associated with penetration and invasion of the ovary. The rate of ovary colonization differed in three male-sterile lines that also differed in ergot susceptibility. This work demonstrates a possible histological basis for partial resistance in male-sterile sorghum lines that could lay the foundation for variety improvement through further breeding and selection

Starch, Proteins and Minerals Content of Papua New Guinea Taro (Colocasia esculenta) Corms Starch, Proteins and Minerals Content of Papua New Guinea Taro (Colocasia esculenta) Corms

Abstract The aim of the presented investigation was to study chemical composition variation in starch, protein and minerals found in corms of ten taro cultivars from Papua New Guinea, South Pacific. The chemical analyses were performed on oven dried materials. The starch content ranged from 66 % to 79 %, mean content of crude protein was 3.72 g/100g. Among minerals, K was the most abundant (1.77 %), followed by P (0.43 %), Ca (1230 mg/kg) and Mg (976 mg/kg). The analyzed materials could also be considered as moderate sources of Zn (22.10 mg/kg), Fe (19.63 mg/kg), and Cu (6.87 mg/kg). The content of Mn was rather low (5.12 mg/kg)