Cornelia M. Bender

University of the Free State | ufs · Department of Plant Sciences

Allium crops are commonly grown in South Africa and harvested as either fresh produce for the domestic and export markets or as seed. Apart from occasional outbreaks on garlic, rust is problematic as a cosmetic disease with unappealing uredinia regularly observed on freshly packed produce of bunching onion and leek in supermarkets. Spore morphology...

The continuous emergence of new Puccinia striiformis Westend f. sp. tritici Erikss ( Pst ) races requires a sustained search for useful sources of resistance. A CIMMYT bread wheat line (pedigree: Milan/S87230//Babax; renamed NSRPan4) was identified as highly resistant to South African Pst races. A recombinant inbred line (RIL) mapping population wa...

Fig rust, caused by Cerotelium fici, was first recorded in South Africa in 1927. Recent observations have revealed high incidence of rust and untimely defoliation of fig trees (Ficus carica) in residential gardens and commercial orchards. Using phylogenetic analysis, the causal organism of a fig rust isolate (PREM63073) collected in 2020 was confir...

Rust fungi are important plant pathogens and have been extensively studied on crops and other host plants worldwide. This study describes the heterecious life cycle of a rust fungus on Digitaria eriantha (finger grass) and the Solanum species S. lichtensteinii (large yellow bitter apple), S. campylacanthum (bitter apple), and S. melongena (eggplant...

Histological investigations elucidate infection structure development and the subsequent colonization process of rust pathogens in their cereal hosts. No comprehensive information exists for the infection process of the wheat stem rust fungus, Puccinia graminis f. sp. tritici (Pgt), on triticale, an amphiploid species carrying both the wheat and ry...

Rust diseases, although seasonal, have been severe constraints in wheat production in South Africa for almost 300 years. Rust research gained momentum with the institution of annual surveys in the 1980s, followed by race identification, an understanding of rust epidemiology, and eventually a focused collaboration amongst pathologists, breeders and...

Barley, host to the wheat and rye attacking forms of the stem rust pathogen, Puccinia graminis (Pg), is considered inherently more resistant to Pg than wheat. To investigate whether this enhanced basal defence is associated with early infection or colonisation processes, adult plants of selected barley and wheat entries were inoculated with Pg f. s...

Traditional race phenotyping of cereal rusts is based on the pathogenicity of field isolates on seedlings using a set of differential host lines. These lines are regularly planted in the field, often as part of trap nurseries. In trap nurseries the primary objective is to assess the occurrence of isolates with virulence or avirulence on key resista...

The release of commercial wheat cultivars resistant to stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), remains one of the primary objectives in many breeding programs. Previous studies of adult plant resistance derived from the winter wheat cultivar Cappelle-Desprez identified the quantitative trait loci (QTL) QYr.ufs-2A, QYr.ufs-...

The bread wheat cultivar Kariega has maintained its stripe rust resistance since the first detection of Puccinia striiformis f. sp. tritici (Pst) in South Africa during 1996. Doubled haploid (MP [mapping population]) lines derived from a Kariega x Avocet S cross carrying consistently detected adult plant resistance (APR) QTL/gene combinations, were...

Rusts are a significant threat to sustainable wheat production in South Africa. In addition to accurate genotyping, resistance breeding and surveillance, a better understanding of the epidemiology of rust pathogens will facilitate their control. This includes an improved understanding of over-summering and the occurrence of early-season inoculum on...

Depending on the pathogenicity of the stripe rust fungus Puccinia striiformis f. sp. tritici, the nature of resistance in the wheat host plant, and the environment, a broad range of disease phenotypes can be expressed. Therefore, the phenotyping of partial adult plant stripe rust resistance requires reliable and repeatable procedures, especially un...

Puccinia graminis f. sp. tritici race Ug99 (syn. TTKSK) has been identified as a major threat to wheat production based on its broad virulence. Despite its importance, the effect of Ug99 on different types of resistance in wheat has not been thoroughly researched. In field trials conducted with P. graminis f. sp. tritici race PTKST (Ug99 race group...

Race 2SA55 of the wheat stem rust pathogen, Puccinia graminis f. sp. tritici, was described for the first time during 2000 in South Africa. This race is of particular interest as it was the first local report of increased virulence towards barley cultivars by wheat stem rust. Using three original accessions of 2SA55 from the rust collection of the...

Phenotyping of wheat stripe rust in genetic studies has traditionally relied on quantifying disease by means of the modified Cobb Scale. This approach requires scoring of disease severity and response type, either on flag leaves or on a whole plot basis. The use of spectral crop sensors in wheat phenotyping has raised the question of whether this o...

Following the emergence of the Ug99 lineage of Puccinia graminis f. sp. tritici (Pgt) a collective international effort has been undertaken to identify new sources of wheat stem rust resistance effective against these races. Analyses were undertaken in a collection of wheat genotypes gathered from across Africa to identify stem rust resistance effe...

Screening for adult plant resistance in wheat to stem rust, caused by Puccinia graminis f. sp. tritici, is generally conducted in field plots. Although such evaluations are successful if managed properly, field ratings are time consuming, expensive, weather dependent, and open to inoculum of unwanted races or other confounding diseases. The objecti...

Background: Secale strictum subsp. africanum, a self-fertile and perennial wild rye species, is endemic to the Roggeveld Mountains of the south-western Karoo, South Africa. Despite historical abundance on the Roggeveld plateau, S. strictum subsp. africanum is currently threatened with extinction. Many reasons have been given for its decline, includ...

Three major quantitative trait loci (QTL) contribute to the durable adult plant stripe rust resistance in the high-quality bread wheat cultivar Kariega; QYr.sgi-2B.1 and QYr.sgi-4A.1, and the pleiotropic resistance gene Lr34/Yr18/Sr57. While marker-assisted selection is currently being used to incorporate the Kariega stripe rust adult plant resista...

The appearance and spread of races of Puccinia graminis f. sp. tritici with virulence for the Sr31 resistance gene has renewed interest in breeding for durable resistance to stem rust of wheat. Since the occurrence of stem rust has been low in South Africa until the detection of race TTKSF in 2000, breeding for resistance to this disease has not be...

Characterising resistance at different levels of expression is important in understanding host defence mechanisms and the improvement of durable disease resistance in crop plants. Histological reactions of the lentil cultivars EL-142 (susceptible) and Gudo (resistant) to infection by Uromyces viciae-fabae, were investigated by means of fluorescence...

Following the appearance of stripe rust in South Africa in 1996, efforts have been made to identify new sources of durable resistance. The French cultivar Cappelle-Desprez has long been considered a source of durable, adult plant resistance (APR) to stripe rust. As Cappelle-Desprez contains the seedling resistance genes Yr3a and Yr4a, wheat lines w...

Two new races of the wheat (Triticum aestivum L.) stem rust pathogen, representing the fifth and sixth variants described within the Ug99 lineage, were detected in South Africa. Races TTKSP and PTKST (North American notation) were detected in 2007 and 2009, respectively. Except for Sr24 virulence, race TTKSP is phenotypically identical to TTKSF, a...

A new race of Puccinia triticina was collected from common wheat (Triticum aestivum) in the Eastern and Western Cape provinces during the annual rust survey in 2009. Six single-pustule isolates from a field collection, which were shown to be a new race in preliminary analyses, were inoculated onto seedlings of 16 Thatcher (Tc) near-isogenic differe...

Microsatellite analysis of ten South African races of Puccinia triticina, the causal organism of leaf rust of wheat (Triticum aestivum), divided the population into two groups sharing 32% genetic similarity. In the first group, race 3SA145 (Agricultural Research Council notation) clustered with 3SA122 and 3SA125, two races that have not been detect...

Adult plant resistance to stripe (yellow) rust in the wheat cultivar Kariega has previously been ascribed to a major quantitative trait locus (QTL) on each of chromosomes 2B and 7D, along with a number of minor QTL. We have extended both the size of the cv. Kariega×cv. Avocet S mapping population, and the marker coverage within it, by assembling a...

Isolates of Puccinia graminis f. sp. tritici belonging to the Ug99 race group are virulent to a broad spectrum of resistance genes, rendering most of the world's wheat germplasm susceptible to stem rust (3). Following the initial detection of Ug99 (TTKSK, North American [NA] race notation) in Uganda, virulence to the widely used Sr31 resistance gen...

The wheat leaf rust resistance gene Lr32 was transferred from Aegilops tauschii Coss. to bread wheat (Triticum aestivum L.) (1). Despite virulence for Lr32 in some isolates from Bulgaria, Israel, and Turkey, the gene has been reported to be effective in Australia, Mexico, the United States, and South Africa (1,2). A leaf rust isolate that differed...

Complete adult plant resistance (APR) to stripe rust of the wheat cultivar Kariega was previously ascribed to two major quantitative trait loci (QTL) on chromosomes 2B and 7D and three minor QTL. In the present study the Kariega x Avocet S doubled haploid population was increased from 150 to 254 individuals and the map improved by adding Diversity...

The appearance and anticipated spread of race TTKS (syn. Ug99) of Puccinia graminis f. sp. tritici have renewed interest in breeding for durable resistance to stem rust of wheat. In an attempt to determine the current status of stem rust resistance in South African (SA) bread wheat, 67 cultivars and lines were tested with US and East African races...

For accurate lentil (Lens culinaris) rust phenotyping in controlled environments, conditions for infection should be optimized. Therefore, the effects of temperature on germination and germ tube growth of Uromyces viciae-fabae, as well as the effect of different dew periods, were quantified. In all experiments urediniospores of a single-pustule iso...

Four components of resistance to Uromyces viciae-fabae, namely, latent period (LP), infection efficiency (IE), pustule size (PS) and spore production (SP) were evaluated on lentil (Lens culinaris) in glasshouse experiments. Four cultivars, Gudo, R-186, FLIP-87-66L and FLIP-89-60L, with different levels of resistance, and the susceptible check EL-14...

The life-cycle of Puccinia sorghi, a heteroecious fungus, consists of five well-defined spore stages. The uredinial and telial stages are completed on the primary maize host whereas pycnial and aecial stages occur on Oxalis comiculata (creeping sorrel), a perennial and widespread weed. Although the sexual phase of maize rust has been known to occur...

Resistance to rust diseases of common wheat (Triticum aestivum) has often been transferred from related species. These alien genes usually mediate hypersensitive, and frequently non-durable, resistance to leaf rust caused by Puccinia triticina. Partial resistance may be more durable than hypersensitive resistance and is expressed by a susceptible h...

Evidence exists that certain genes for resistance to leaf rust in wheat, e.g. Lr13 and Lr34, may interact with other genes to condition higher levels of resistance than that ge conferred by each gene individually. In this study, the hypothesis that Lr12 and Lr13, both genes for adult plant resistance to Puccinia recondita Roberge ex. Desmaz f. sp....

The deployment and maintenance of durable resistance to leaf rust, caused by Puccinia recondita f. sp. tritici, remain a challenge for wheat breeders worldwide. Durable resistance to leaf and stripe rust has often been associated with the linked Lr34 and Yr18 genes. In South Africa Lr34 can be detected in wheat (Triticum aestivum L.) seedlings at l...

Monogenic resistance in wheat (Triticum aestivum L.) to leaf rust, caused by Puccinia recondite Rob. ex. Desm. f. sp. tritici, has generally not been durable. Durable resistance, as well as an improved expression of resistance, have been associated with Lr gene combinations. In this study, the assumption that Lr12 and Lr13 may interact to condition...

Two new races of the wheat (Triticum aestivum L.) stem rust pathogen, representing the fifth and sixth variants described within the Ug99 lineage, were detected in South Africa. Races TTKSP and PTKST (North American notation) were detected in 2007 and 2009, respectively. Except for Sr24 virulence, race TTKSP is phenotypically identical to TTKSF, a...

Thesis (M.Sc.) - University of the Orange Free State, 1995.