- Email: [email protected]
Grey leaf spot disease of maize and food security research
Abstracts
early-diverging lineage. Although none of the groupings correspond to the previous infrageneric classification, they can all largely be identified by morphological characters. A comprehensive taxonomic revision of Pteronia was also completed in which we recognised 75 species of which three are new. The main morphological groups and changes of classification as well as the results of the phylogenetic analyses will be presented.
doi:10.1016/j.sajb.2017.01.027
Grey leaf spot disease of maize and food security research D.K. Berger Department of Plant and Soil Sciences, Forestry and Agricultural Biotechnology Institute (FABI), Genomics Research Institute (GRI), University of Pretoria, Pretoria, South Africa E-mail address: [email protected] Maize is an important staple food in South Africa cultivated on large commercial farms and small-holder farms. Grey leaf spot (GLS) disease of maize is characterized by leaf lesions which, in severe cases, can coalesce to form blighted leaves, resulting in grain yield losses. The GLS-maize research programme at the University of Pretoria focuses on the molecular biology of the pathosystem. Field trials of a maize mapping population were conducted over three seasons in several environments in KwaZulu-Natal province, where the disease is rife. Quantitative loci for disease resistance were identified. Transcriptome analysis identified gene regulatory networks associated with susceptibility and resistance. Population genetic analysis of the fungus Cercospora zeina that causes GLS indicated that diverse isolates are scattered throughout the region. This implies that maize breeders should deploy different maize resistance in South Africa to ensure food security.
doi:10.1016/j.sajb.2017.01.028
On the problem of defining monophyletic genera in the southern African Asteraceae N.G. Bergh The Compton Herbarium, Kirstenbosch Research Centre, South African National Biodiversity Institute, Private Bag X7, Newlands 7735, Cape Town, South Africa The Bolus Herbarium, Department of Biological Sciences, H.W. Pearson Building, University of Cape Town, Rhodes Gift, Rondebosch 7707, Cape Town, South Africa E-mail address: [email protected] Traditional phylogenetic studies on the species-level relationships within the daisy family in South Africa, particularly within tribe Gnaphalieae (the everlastings) are often hampered by lack of phylogenetic resolution. A limited number of universal sequencing regions are available for such studies, but the costs of massively-parallel sequencing prohibit, at this point, large-scale application to multiple groups. The incorporation of morphological data into phylogenetic analyses may not readily solve the problem. In several instances, we resolve the taxonomic problems by “lumping”: combining several small genera into a single larger genus. The issue of whether lack of resolution is due to extremely recent radiation is difficult to answer,
327
as different molecular clock calibration schemes can result in very variable age estimates. doi:10.1016/j.sajb.2017.01.029
Exogenous methylglyoxal alleviates zirconium toxicity in Brassica rapa L. seedling shoots Y. Bless, L. Ndlovu, A. Gokul, M. Keyster Environmental Biotechnology Laboratory, University of the Western Cape, Private Bag X17, Bellville 7535, South Africa E-mail address: [email protected] (M. Keyster) Plastic pots were filled with 1 kg of soil to sand mixture (1:3) and were pre-treated with 200 ml’s of deionised water (controls), deionised water containing methylglyoxal, deionised water containing 1 mM zirconium and deionised water containing methylglyoxal and 1 mM zirconium, separately. Brassica rapa cv. Nooitgedacht seeds were surface sterilized and allowed to germinate to completion (9 days) under each separate treatment. After scoring the germination percentage, plants were left to grow for an additional 14 days and during this period, plants were treated twice a week with the four separate treatments. Seedling shoots were harvested and fresh material was dried to assess dry weights. Fresh material was also used to determine cell viability and superoxide content. The rest of the seedling shoots were snap frozen in liquid nitrogen and ground into fine powder for storage at -80°C. The frozen material was used to determine contents of chlorophyll, methylglyoxal, hydrogen peroxide, conjugated diene, hydroxyl radical and zirconium. The rest of the frozen material was used for total protein extraction for subsequent assessment of enzymatic activities such as superoxide dismutase, ascorbate peroxidase, catalase, and glyoxalase I. Methylglyoxal treatment increased the germination percentage as well as overall seedling shoot growth of B. rapa when compared to the controls. This increase could be attributed to the regulation of reactive oxygen species (ROS) by antioxidant enzymes. Zirconium treatment decreased the germination percentage of B. rapa as well as the seedling shoot growth possibly through overproduction of toxic ROS. However, when seeds were treated with a combination of methylglyoxal and zirconium, we observed an increased in germination percentage as well as seedling shoot growth when compared to the zirconium only treatment.
doi:10.1016/j.sajb.2017.01.030
Defining the drivers of above and belowground biomass allocation, phylogeography and phenology of Sarcocornia tegetaria S. Steffen, Mucina & G. Kadereit (Amaranthaceae) across a geographical gradient C.E. Brown, A. Rajkaran Department of Biodiversity and Conservation Biology, Faculty of Natural Sciences, University of the Western Cape, Robert Sobukwe Road, Bellville 7535, South Africa E-mail address: [email protected] (C.E. Brown) Genetic research has revealed that Sarcocornia tegetaria may occur as two different lineages in warm temperate and cold temperate regions in South Africa and the objective of this study was to determine the exact location where the lineages split, differences in
early-diverging lineage. Although none of the groupings correspond to the previous infrageneric classification, they can all largely be identified by morphological characters. A comprehensive taxonomic revision of Pteronia was also completed in which we recognised 75 species of which three are new. The main morphological groups and changes of classification as well as the results of the phylogenetic analyses will be presented.
doi:10.1016/j.sajb.2017.01.027
Grey leaf spot disease of maize and food security research D.K. Berger Department of Plant and Soil Sciences, Forestry and Agricultural Biotechnology Institute (FABI), Genomics Research Institute (GRI), University of Pretoria, Pretoria, South Africa E-mail address: [email protected] Maize is an important staple food in South Africa cultivated on large commercial farms and small-holder farms. Grey leaf spot (GLS) disease of maize is characterized by leaf lesions which, in severe cases, can coalesce to form blighted leaves, resulting in grain yield losses. The GLS-maize research programme at the University of Pretoria focuses on the molecular biology of the pathosystem. Field trials of a maize mapping population were conducted over three seasons in several environments in KwaZulu-Natal province, where the disease is rife. Quantitative loci for disease resistance were identified. Transcriptome analysis identified gene regulatory networks associated with susceptibility and resistance. Population genetic analysis of the fungus Cercospora zeina that causes GLS indicated that diverse isolates are scattered throughout the region. This implies that maize breeders should deploy different maize resistance in South Africa to ensure food security.
doi:10.1016/j.sajb.2017.01.028
On the problem of defining monophyletic genera in the southern African Asteraceae N.G. Bergh The Compton Herbarium, Kirstenbosch Research Centre, South African National Biodiversity Institute, Private Bag X7, Newlands 7735, Cape Town, South Africa The Bolus Herbarium, Department of Biological Sciences, H.W. Pearson Building, University of Cape Town, Rhodes Gift, Rondebosch 7707, Cape Town, South Africa E-mail address: [email protected] Traditional phylogenetic studies on the species-level relationships within the daisy family in South Africa, particularly within tribe Gnaphalieae (the everlastings) are often hampered by lack of phylogenetic resolution. A limited number of universal sequencing regions are available for such studies, but the costs of massively-parallel sequencing prohibit, at this point, large-scale application to multiple groups. The incorporation of morphological data into phylogenetic analyses may not readily solve the problem. In several instances, we resolve the taxonomic problems by “lumping”: combining several small genera into a single larger genus. The issue of whether lack of resolution is due to extremely recent radiation is difficult to answer,
327
as different molecular clock calibration schemes can result in very variable age estimates. doi:10.1016/j.sajb.2017.01.029
Exogenous methylglyoxal alleviates zirconium toxicity in Brassica rapa L. seedling shoots Y. Bless, L. Ndlovu, A. Gokul, M. Keyster Environmental Biotechnology Laboratory, University of the Western Cape, Private Bag X17, Bellville 7535, South Africa E-mail address: [email protected] (M. Keyster) Plastic pots were filled with 1 kg of soil to sand mixture (1:3) and were pre-treated with 200 ml’s of deionised water (controls), deionised water containing methylglyoxal, deionised water containing 1 mM zirconium and deionised water containing methylglyoxal and 1 mM zirconium, separately. Brassica rapa cv. Nooitgedacht seeds were surface sterilized and allowed to germinate to completion (9 days) under each separate treatment. After scoring the germination percentage, plants were left to grow for an additional 14 days and during this period, plants were treated twice a week with the four separate treatments. Seedling shoots were harvested and fresh material was dried to assess dry weights. Fresh material was also used to determine cell viability and superoxide content. The rest of the seedling shoots were snap frozen in liquid nitrogen and ground into fine powder for storage at -80°C. The frozen material was used to determine contents of chlorophyll, methylglyoxal, hydrogen peroxide, conjugated diene, hydroxyl radical and zirconium. The rest of the frozen material was used for total protein extraction for subsequent assessment of enzymatic activities such as superoxide dismutase, ascorbate peroxidase, catalase, and glyoxalase I. Methylglyoxal treatment increased the germination percentage as well as overall seedling shoot growth of B. rapa when compared to the controls. This increase could be attributed to the regulation of reactive oxygen species (ROS) by antioxidant enzymes. Zirconium treatment decreased the germination percentage of B. rapa as well as the seedling shoot growth possibly through overproduction of toxic ROS. However, when seeds were treated with a combination of methylglyoxal and zirconium, we observed an increased in germination percentage as well as seedling shoot growth when compared to the zirconium only treatment.
doi:10.1016/j.sajb.2017.01.030
Defining the drivers of above and belowground biomass allocation, phylogeography and phenology of Sarcocornia tegetaria S. Steffen, Mucina & G. Kadereit (Amaranthaceae) across a geographical gradient C.E. Brown, A. Rajkaran Department of Biodiversity and Conservation Biology, Faculty of Natural Sciences, University of the Western Cape, Robert Sobukwe Road, Bellville 7535, South Africa E-mail address: [email protected] (C.E. Brown) Genetic research has revealed that Sarcocornia tegetaria may occur as two different lineages in warm temperate and cold temperate regions in South Africa and the objective of this study was to determine the exact location where the lineages split, differences in