Vegetative Compatibility Among Isolates of Colletotrichum gloeosporioides from Yam (Dioscorea spp.) in Nigeria

Abstract

Isolates of Colletotrichum gloeosporioides obtained from yam‐based cropping systems in Nigeria, previously characterized on the basis of morphology, virulence and rDNA internal transcribed spacer (ITS) sequence variation were further compared for vegetative compatibility (VC). Chlorate‐resistant nitrate non‐utilizing (nit) mutants were generated from the isolates and used in complementation (heterokaryon) tests. Tests of VC between complementary mutants from different isolates indicated the presence of several genotypes within a single field, suggesting limited clonal spread. In some cases, isolates obtained from the same lesion were observed to belong to different vegetative compatibility groups (VCGs). No compatibility was observed between isolates of the highly virulent slow‐growing grey (SGG), the moderately virulent fast‐growing salmon (FGS) and the avirulent/weakly virulent fast‐growing grey (FGG) strains. Forty‐one C. gloeosporioides isolates belonged to 28 VCGs, giving a genotype diversity estimate of 0.68. This diversity confirmed the high variability of the pathogen population as revealed by previous characterization studies, however, a correlation between VCGs and isolate groupings based on morphology and virulence was not found. The finding that an isolate from weed was compatible with yam isolates indicated that transfer of important traits, such as virulence, may take place between isolates from yam and non‐yam hosts. The VCG diversity revealed by this study suggests that in addition to asexual reproduction, sexual reproduction may play an important role in the epidemiology of anthracnose on yam.

Preliminary Studies On Production And Partial Purification Of Toxins Associated With Black Tar Disease Of Yam (Dioscorea Species) In Makurdi, Benue State, Nigeria.

“…Green and Simons [16], Akem [3], and Abang [17] also isolated and recognized C. gloeosporioides as the major pathogen of yam dieback and necrosis, from leaves, stems, tubers and botanic seeds of yam in some parts of Nigeria. Yam infection by this pathogen has been found to affect photosynthetic activities leading to yield loses [1].…”

“…has been identified as an important staple food for millions of people worldwide [1]. It has been estimated that out of the world's production of over 30 million tones of yams, an average of over 25% of the yield is lost annually to disease and pest [2,1], particularly anthracnose or black tar disease, which exerts a devastating impact on its productivity [3].…”

“…has been identified as an important staple food for millions of people worldwide [1]. It has been estimated that out of the world's production of over 30 million tones of yams, an average of over 25% of the yield is lost annually to disease and pest [2,1], particularly anthracnose or black tar disease, which exerts a devastating impact on its productivity [3]. Bailey and Jegger [4] and Joseph et al [5] reported that, black tar disease affecting yam foliage is one of the most important yam diseases with a worldwide distribution, found mainly in the subtropical and tropical regions of the world.…”

“…Organisms causing this disease are facultative parasites known to produce metabolic substances (toxins) causing disease of plants generally referred to as anthracnose on a wide range of economically important plant crops including yam [5,6,7]. In several places where yam is cultivated, the disease has been reported to have infected and caused varying degrees of leaf necrosis and vines die back, resulting to a reduction in the effective photosynthetic surface area of the crop and consequently a reduction in the ability of the yam tuber to store food reserves [1]. Black tar disease of yam is therefore a major constraint to yam production [8].This study will provide base line information on yam black tar pathology in the study area, where yam is a major staple food crop.…”

Caracterización química y evaluación de la actividad antifúngica del aceite esencial foliar de Lippia alba contra Colletotrichum gloeosporioides

“…(Giblin et al 2010, Guetsky et al 2005, mango (Mangifera indica L.) (Giblin et al 2010, Serra et al 2011, ñame (Dioscorea spp.) (Raj et al 2013, Abang et al 2004, entre otros.…”