Walter J. Kaiser

A second gene for resistance to race 4 of Fusarium wilt in chickpea and linkage with a RAPD marker

Fusarium wilt caused by Fusarium oxysporum Schlechtend.: Fr f. sp. ciceris (Padwick) Matuo & Sato is a devastating disease of chickpea. The current study was conducted to determine the inheritance of the gene(s) for resistance to race 4 of fusarium wilt and to identify linked RAPD markers using an early wilting line, JG-62, as a susceptible parent. Genetic analysis was performed on the F1s, F2s and F3 families from the cross of JG-62 × Surutato-77. The F3 families were inoculated with a spore suspension of the race 4 wilt pathogen and the results were used to infer the genotypes of the parent F2 plants. Results indicated that two independent genes controlled resistance to race 4. Linkage analysis of candidate RAPD marker, CS-27700, and the inferred F2 phenotypic data showed that this marker locus is linked to one of the resistance genes. Allelism indicated that the two resistance sources, Surutato-77 and WR-315, shared common alleles for resistance and the two susceptible genotypes, C-104 and JG-62, carried alleles for susceptibility. The PCR-based marker, CS-27700, was previously reported to be linked to the gene for resistance to race 1 in a different population which suggested that the genes for resistance to races 1 and 4 are in close proximity in the Cicer genome.

Diseases of chickpea, lentil, pigeon pea, and tepary bean in Continental United States and Puerto Rico

The Leguminosae (pea or bean family) are composed of some 690 genera and 18,000 species (Purseglove, 1968). It is the second largest family of seed plants (following the Gramineae) (Aykroyd and Doughty, 1964). Within the Leguminosae, there are 18-20 species that are cultivated widely for their edible seeds which are high in protein (17-25+%) (Aykroyd and Doughty, 1964). The seeds of legumes are second only to cereals as the most important source of food for humans and animals (National Academy of Sciences, 1979). The term food legume generally is given to species of Leguminosae, the seeds, pods, and/or leaves of which are eaten by humans. The word pulse is used in some countries colonized by Great Britain, like India and Pakistan, to denote the dry, mature seeds which are consumed by humans. A chronic protein deficiency exists in most developing countries of the world (Mayer, 1976). In these countries food legumes usually provide the main, and at times the only, source of protein and essential amino acids in the diets of poorer inhabitants for social, economic, or religious reasons. Legumes are an important complement to diets heavily dependent on high carbohydrate foods (cereals and root and tuber crops) (National Academy of Sciences, 1979). In the United States and its territories, several food legumes are grown on a commercial scale. After soybean [Glycine max (L.) Merr.] and peanut (Arachis hypogaea L.) (which are also classified as oil crops), bean (Phaseolus vulgaris L.) is the most important food legume cultivated in the United States (USDA, 1979a). The seeds of some food legumes, like bean, pea (Pisum sativum L.), soybean, and lentil (Lens culinaris Medik.) are exported in large quantities and aid in correcting the nations sizeable balance of trade deficits (USDA, 1979a). In most developed countries of the world, with the exception of Japan, food legumes are consumed in small amounts, and, therefore, contribute minimally to satisfying daily protein requirements. Protein from animal sources satisfies most of that need, but this is a very inefficient method of producing protein (Mayer, 1976). With the recent dramatic rise in the cost of energy and nitrogenous fertilizers, a search will be made to find cheaper, energy-saving methods of increasing food production. Food legumes will undoubtedly assume a more important role in providing a larger share of the protein requirements of the inhabitants of many developed countries, including the United States, particularly as the price of

Use of metabolomics for the chemotaxonomy of legume-associated Ascochyta and allied genera.

Chemotaxonomy and the comparative analysis of metabolic features of fungi have the potential to provide valuable information relating to ecology and evolution, but have not been fully explored in fungal biology. Here, we investigated the chemical diversity of legume-associated Ascochyta and Phoma species and the possible use of a metabolomics approach using liquid chromatography-mass spectrometry for their classification. The metabolic features of 45 strains including 11 known species isolated from various legumes were extracted, and the datasets were analyzed using chemometrics methods such as principal component and hierarchical clustering analyses. We found a high degree of intra-species consistency in metabolic profiles, but inter-species diversity was high. Molecular phylogenies of the legume-associated Ascochyta/Phoma species were estimated using sequence data from three protein-coding genes and the five major chemical groups that were detected in the hierarchical clustering analysis were mapped to the phylogeny. Clusters based on similarity of metabolic features were largely congruent with the species phylogeny. These results indicated that evolutionarily distinct fungal lineages have diversified their metabolic capacities as they have evolved independently. This whole metabolomics approach may be an effective tool for chemotaxonomy of fungal taxa lacking information on their metabolic content.

Karyotype polymorphism and chromosomal rearrangement in populations of the phytopathogenic fungus, Ascochyta rabiei.

The fungus Ascochyta rabiei is the causal agent of Ascochyta blight of chickpea and the most serious threat to chickpea production. Little is currently known about the genome size or organization of A. rabiei. Given recent genome sequencing efforts, characterization of the genome at a population scale will provide a framework for genome interpretation and direction of future resequencing efforts. Electrophoretic karyotype profiles of 112 isolates from 21 countries revealed 12-16 chromosomes between 0.9 Mb and 4.6 Mb with an estimated genome size of 23 Mb-34 Mb. Three general karyotype profiles A, B, and C were defined by the arrangement of the largest chromosomes. Approximately one-third of isolates (group A) possessed a chromosome larger than 4.0 Mb that was absent from group B and C isolates. The ribosomal RNA gene (rDNA) cluster was assigned to the largest chromosome in all except four isolates (group C) whose rDNA cluster was located on the second largest chromosome (3.2 Mb). Analysis of progeny from an in vitro sexual cross between two group B isolates revealed one of 16 progeny with an rDNA-encoding chromosome larger than 4.0 Mb similar to group A isolates, even though a chromosome of this size was not present in either parent. No expansion of the rDNA cluster was detected in the progeny, indicating the increase in chromosome size was not due to an expansion in number of rDNA repeats. The karyotype of A. rabiei is relatively conserved when compared with published examples of asexual ascomycetes, but labile with the potential for large scale chromosomal rearrangements during meiosis. The results of this study will allow for the targeted sequencing of specific isolates to determine the molecular mechanisms of karyotype variation within this species.

Mycosphaerella lupini sp. nov., a serious leaf spot disease of perennial lupin in southcentral Idaho, USA

Mycosphaerella lupini is described as the te- leomorph of Thedgonia lupini, the organism com- monly associated with a leaf spot disease of perennial lupin in the U.S.A. The latter organism is also shown to be distinct from Didymella lupini, which is associ- ated with a Phoma anamorph, and occurs predomi- nantly on overwintered lupin stems. Thedgonia lupi- ni, which is known to produce conidia in disarticu- lating chains, is shown to do so by sympodial as well as percurrent proliferation. The genus Thedgonia is accordingly emended to incorporate both types of proliferation of the conidiogenous locus. Mycospha- erella lupini is the first teleomorph linked to the ana-

Some effects of water potential upon endophytic Acremonium spp. in culture

Acremonium coenophialum, A. starrii, and A. typhinum were grown on potato dextrose agar (PDA) amended with KC1 (PDA + KC1) or sucrose (PDA + S) to attain a wide range of osmotic water potentials. Radial growth was greatest between -0.3 MPa (PDA without amendment) and -3.0 to -4.0 MPa, below which growth diminished to near zero at -8 MPa. Acremonium isolates grew well on corn

The effect of water potential upon radial growth of Epichloe and Claviceps purpurea isolates in culture

Claviceps purpurea and single isolates of Epichloe amaryllans and E. baconii grew well between -0.3 and -3.0 MPa water potential, below which growth declined with declining water potential. The isolates of E. clarkii and of E. typhina were less tol- erant to reduced water potential. Antibiotic was weakly produced by some Epichloe isolates but not