scholarly journals Identification of QTLs Controlling Resistance/Tolerance to Striga hermonthica in an Extra-Early Maturing Yellow Maize Population

Agronomy ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1168 ◽  
Author(s):  
Baffour Badu-Apraku ◽  
Samuel Adewale ◽  
Agre Paterne ◽  
Melaku Gedil ◽  
Robert Asiedu
Keyword(s):  
Candidate Genes ◽  
Marker Assisted Selection ◽  
Defense Mechanisms ◽  
Sub Saharan Africa ◽  
Striga Hermonthica ◽  
Maize Production ◽  
Maize Population ◽  
Striga Resistance ◽  
Sub Saharan ◽  
Indicator Traits

Striga hermonthica parasitism is a major constraint to maize production in sub-Saharan Africa with yield losses reaching 100% under severe infestation. The application of marker-assisted selection is highly promising for accelerating breeding for Striga resistance/tolerance in maize but requires the identification of quantitative trait loci (QTLs) linked to Striga resistance/tolerance traits. In the present study, 194 F2:3 families of TZEEI 79 × TZdEEI 11 were screened at two Striga-endemic locations in Nigeria, to identify QTLs associated with S. hermonthica resistance/tolerance and underlying putative candidate genes. A genetic map was constructed using 1139 filtered DArTseq markers distributed across the 10 maize chromosomes, covering 2016 cM, with mean genetic distance of 1.70 cM. Twelve minor and major QTLs were identified for four Striga resistance/tolerance adaptive traits, explaining 19.4%, 34.9%, 14.2% and 3.2% of observed phenotypic variation for grain yield, ears per plant, Striga damage and emerged Striga plants, respectively. The QTLs were found to be linked to candidate genes which may be associated with plant defense mechanisms in S. hermonthica infested environments. The results of this study provide insights into the genetic architecture of S. hermonthica resistance/tolerance indicator traits which could be employed for marker-assisted selection to accelerate efficient transfer host plant resistance genes to susceptible genotypes.

scholarly journals INTROGRESSION OF STRIGA RESISTANCE INTO POPULAR SUDANESE SORGHUM VARIETIES USING MARKER ASSISTED SELECTION

2016 ◽  
Vol 1 (1) ◽  
pp. 49 ◽  
Author(s):  
Rasha Ali ◽  
Charles T. Hash ◽  
Odeny Damaris ◽  
Adil Elhussein ◽  
Abdalla H. Mohamed
Keyword(s):  
Marker Assisted Selection ◽  
Integrated Management ◽  
Management Strategies ◽  
Sub Saharan Africa ◽  
Effective Control ◽  
Progress Curve ◽  
Striga Resistance ◽  
Infested Field ◽  
Backcross Populations ◽  
Sub Saharan

Witchweed (Strigas spp.) is one of the most important cereals production constraints globally and is projected to worsen with anticipated climate change. It is especially a devastating parasitic weed in Sub-Saharan Africa and parts of Asia. Integrated management strategies that depend mainly on host plant resistance provide the most effective control mechanism for Striga. We used molecular marker-assisted backcrossing to introgress Striga resistance from a resistant genotype, N13, into agronomically important genetic backgrounds (Tabat and Wad Ahmed). Backcross populations BC3S3 were generated and genotyped using Simple Sequence Repeat (SSR) and Diversity Arrays Technology (DArT) markers. A total of 17 promising backcross progenies were selected and screened in Striga infested field alongside their parents. The Area Under Striga Progress Curve (AUSPC) showed significant decrease in Striga count (920-7.5) resulting in a 97-189% increase in yield under Striga pressure. Our results demonstrate the practical application of marker assisted selection (MAS) to generate farmer-preferrd Striga resistant lines in Sudan.

scholarly journals Breeding maize ( Zea mays ) for Striga resistance: Past, current and prospects in sub‐saharan africa

2021 ◽  
Author(s):  
Abdoul‐Madjidou Yacoubou ◽  
Nouhoun Zoumarou Wallis ◽  
Abebe Menkir ◽  
Valerien A. Zinsou ◽  
Alexis Onzo ◽  
...  
Keyword(s):  
Zea Mays ◽  
Sub Saharan Africa ◽  
Striga Resistance ◽  
Sub Saharan

CHAPTER 5: Maize Lethal Necrosis, An Emerging Threat to Maize Production and Food Security in Sub-Saharan Africa

2020 ◽  
pp. 81-100
Author(s):  
Joel Masanga ◽  
Steven Runo ◽  
Francis Mwatuni ◽  
Cyrus Mugambi Micheni ◽  
Paul Kuria ◽  
...  
Keyword(s):  
Food Security ◽  
Sub Saharan Africa ◽  
Maize Production ◽  
Sub Saharan

scholarly journals Contrasting Response Mechanisms of Maize Lines to Striga hermonthica

Agriculture ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 485
Author(s):  
Nnanna N. Unachukwu ◽  
Abebe Menkir ◽  
Adekemi Stanley ◽  
Ebenezer O. Farombi ◽  
Melaku Gedil
Keyword(s):  
Cost Effective ◽  
Resistance Mechanisms ◽  
Control Measures ◽  
Sub Saharan Africa ◽  
Striga Hermonthica ◽  
Maize Line ◽  
Parasitic Weed ◽  
Resistant Lines ◽  
Sub Saharan ◽  
Better Than

Strigahermonthica (Del.) Benth is a parasitic weed that devastates cereals in Sub-Saharan Africa. Several control measures have been proposed for the parasite, of these, host plant resistance is considered the most cost-effective for poor farmers. Some tolerant/resistant lines have been developed and these lines display tolerance/resistance mechanisms to the parasite. A series of studies was done to investigate some of the mechanisms through which a resistant (TZISTR1108) and a susceptible (5057) maize line responds to S. hermonthica infestation, as well as the effects of parasitism on these lines. In this study, TZISTR1108 stimulated the germination and attachment of fewer S. hermonthica plants than 5057, both in the laboratory and on the field. In TZISTR1108, the growth of the S. hermonthica plants, that successfully attached, was slowed. When compared to the un-infested plants, the infested resistant plants showed fewer effects of parasitism than the infested susceptible plants. The infested TZISTR1108 plants were more vigorous, taller and resembled their un-infected counterparts. There were substantial reductions in the stomatal conductance and nitrogen content of the 5057 upon infestation. The resistant inbred line showed multiple mechanisms of resistance to S. hermonthica infestation. It thrives better than the susceptible line by reducing the attachment of S. hermonthica and it delays the parasite’s development.

scholarly journals Validation of Consensus Quantitative Trait Loci Associated with Resistance to Multiple Foliar Pathogens of Maize

2009 ◽  
Vol 99 (5) ◽  
pp. 540-547 ◽  
Author(s):  
Godfrey Asea ◽  
Bindiganavile S. Vivek ◽  
George Bigirwa ◽  
Patrick E. Lipps ◽  
Richard C. Pratt
Keyword(s):  
Quantitative Trait Loci ◽  
Disease Severity ◽  
Quantitative Trait ◽  
Gray Leaf Spot ◽  
Sub Saharan Africa ◽  
Maize Production ◽  
Resistant Parent ◽  
Trait Loci ◽  
Sub Saharan ◽  
Corn Leaf Blight

Maize production in sub-Saharan Africa incurs serious losses to epiphytotics of foliar diseases. Quantitative trait loci conditioning partial resistance (rQTL) to infection by causal agents of gray leaf spot (GLS), northern corn leaf blight (NCLB), and maize streak have been reported. Our objectives were to identify simple-sequence repeat (SSR) molecular markers linked to consensus rQTL and one recently identified rQTL associated with GLS, and to determine their suitability as tools for selection of improved host resistance. We conducted evaluations of disease severity phenotypes in separate field nurseries, each containing 410 F2:3 families derived from a cross between maize inbred CML202 (NCLB and maize streak resistant) and VP31 (a GLS-resistant breeding line) that possess complimentary rQTL. F2:3 families were selected for resistance based on genotypic (SSR marker), phenotypic, or combined data and the selected F3:4 families were reevaluated. Phenotypic values associated with SSR markers for consensus rQTL in bins 4.08 for GLS, 5.04 for NCLB, and 1.04 for maize streak significantly reduced disease severity in both generations based on single-factor analysis of variance and marker-interval analysis. These results were consistent with the presence of homozygous resistant parent alleles, except in bin 8.06, where markers were contributed by the NCLB-susceptible parent. Only one marker associated with resistance could be confirmed in bins 2.09 (GLS) and 3.06 (NCLB), illustrating the need for more robust rQTL discovery, fine-mapping, and validation prior to undertaking marker-based selection.

A Land Management Based Approach to Integrated Striga hermonthica Control in sub-Saharan Africa

1996 ◽  
Vol 25 (3) ◽  
pp. 157-164 ◽  
Author(s):  
Dana Berner ◽  
Robert Carsky ◽  
Kenton Dashiell ◽  
Jennifer Kling ◽  
Victor Manyong
Keyword(s):  
Land Management ◽  
Management Practices ◽  
Farming Systems ◽  
Integrated Approach ◽  
Cultural Control ◽  
Crop Rotations ◽  
Sub Saharan Africa ◽  
Striga Hermonthica ◽  
Bush Fallow ◽  
Sub Saharan

Striga hermonthica, an obligate root parasite of grasses, Is one of the most severe constraints to cereal production in sub-Saharan Africa. In the recent past, prior to increased production pressure on land, S. hermonthica was controlled in African farming systems by prolonged crop rotations with bush fallow. Because of increasing need for food and concomitant changes in land management practices, however, these fallow rotations are no longer extensively used. Shorter crop rotations and fallow periods have also led to declines in soil fertility which present a very serious threat to African food production. A sustainable solution will be an integrated approach that simultaneously addresses both of these major problems. An integrated programme that replaces traditional bush fallow rotation with non-host nitrogen-fixing legume rotations, using cultivars selected for efficacy in germinating S. hermonthica seeds, is outlined. The programme includes use of S. hermonthlca-free planting material, biological control, cultural control to enhance biological suppressiveness, host-plant resistance, and host-seed treatments.

scholarly journals Cryptococcal Interactions with the Host Immune System

2010 ◽  
Vol 9 (6) ◽  
pp. 835-846 ◽  
Author(s):  
Kerstin Voelz ◽  
Robin C. May
Keyword(s):  
Immune System ◽  
Defense Mechanisms ◽  
Clinical Intervention ◽  
Sub Saharan Africa ◽  
Host Immune System ◽  
Opportunistic Pathogens ◽  
Content Type ◽  
Aids Pandemic ◽  
Immune Deficiencies ◽  
Sub Saharan

ABSTRACT Opportunistic pathogens have become of increasing medical importance over the last decade due to the AIDS pandemic. Not only is cryptococcosis the fourth-most-common fatal infectious disease in sub-Saharan Africa, but also Cryptococcus is an emerging pathogen of immunocompetent individuals. The interaction between Cryptococcus and the host's immune system is a major determinant for the outcome of disease. Despite initial infection in early childhood with Cryptococcus neoformans and frequent exposure to C. neoformans within the environment, immunocompetent individuals are generally able to contain the fungus or maintain the yeast in a latent state. However, immune deficiencies lead to disseminating infections that are uniformly fatal without rapid clinical intervention. This review will discuss the innate and adaptive immune responses to Cryptococcus and cryptococcal strategies to evade the host's defense mechanisms. It will also address the importance of these strategies in pathogenesis and the potential of immunotherapy in cryptococcosis treatment.

scholarly journals Striga Infestation in Kenya: Status, Distribution and Management Options

2013 ◽  
Vol 2 (2) ◽  
pp. 99 ◽  
Author(s):  
Evans Atuti Atera ◽  
Takashige Ishii ◽  
John C. Onyango ◽  
Kazuyuki Itoh ◽  
Tetsushi Azuma
Keyword(s):  
Control Program ◽  
Integrated Approach ◽  
Plant Diseases ◽  
Stress Factors ◽  
Sub Saharan Africa ◽  
Striga Hermonthica ◽  
Management Options ◽  
Qualitative Interaction ◽  
Sub Saharan ◽  
Serious Injury

<p><em>Striga</em> spp. is considered to be the greatest biological constraint to food production in sub-Saharan Africa, a more serious problem than insects, birds and plant diseases. They are among the most specialized root-parasitic plants inflicting serious injury to their host depriving them water, minerals and photosynthate. The greatest diversity of <em>Striga </em>spp. occurs in grassland. However, <em>Striga hermonthica</em> mainly occurs in farmland infecting grasses. The parasite devastating effect is accomplished prior to its emergence from the soil. It may cause yield losses in cereals ranging from 15% under favourable conditions to 100% where several stress factors are involved, thereby affecting the livelihood of millions of resource-poor farmers. Piecemeal approach to address one aspect of <em>Striga</em> problem at a time has been a setback in technology transfer to producers. Future <em>Striga</em> control programs should not be conducted separately, but should rather be conducted in an integrated approach that combines research talents of various institutions. This will facilitate collaborative research and achieve qualitative interaction between stakeholders, which can easily produce reliable technologies that are practical and available to farmers. <em>Striga</em> being a pervasive pest, time is of essence in controlling it. There is an urgent need for the establishment of policies to promote, implement, and ensure a long-term sustainable <em>Striga</em> control program.</p>

Two-tier Witchweed (Striga hermonthica) Resistance in Wild Pearl Millet (Pennisetum glaucum) 29Aw

Weed Science ◽  
2021 ◽  
pp. 1-19
Author(s):  
Olivier Dayou ◽  
Willy Kibet ◽  
Patroba Ojola ◽  
Prakash Irappa Gangashetty ◽  
Susann Wicke ◽  
...  
Keyword(s):  
Pearl Millet ◽  
Pennisetum Glaucum ◽  
Microscopic Analysis ◽  
Resistance Mechanisms ◽  
Sub Saharan Africa ◽  
Striga Hermonthica ◽  
Seedling Biomass ◽  
Natural Infestation ◽  
Sub Saharan ◽  
Vascular Connections

Abstract The parasitic plant purple witchweed [Striga hermonthica (Del.) Benth.] poses a serious threat to cereal production in sub-Saharan Africa. Under natural infestation, the wild pearl millet [Pennisetum glaucum (L.) R. Br.] line 29Aw demonstrates resistance against the parasite, but the mechanism of its resistance is unknown. Striga resistance can be due to: (i) low induction of Striga germination (pre-attachment resistance) or (ii) inhibition of parasite attachment and development (post-attachment resistance). Germination bioassays and root chamber (rhizotron) resistance screening assays were used to determine the extent of pre- and post-attachment Striga resistance in 29Aw compared with the Striga-susceptible SOSAT-C88-P10 variety. Regarding pre-attachment resistance, 29Aw stimulated 10-fold less Striga seed germination at a maximum germination distance of 7.96 ± 2.75 mm from the host root compared with 35.94 ± 2.88 mm in SOSAT-C88-P10. Post-attachment resistance revealed 10 to 19-fold fewer, 2.5-fold shorter, and 28-fold less Striga seedling biomass growing on 29Aw compared to SOSAT-C88-P10. Microscopic analysis showed that Striga penetration in 29Aw was blocked at endodermis and cortex levels. Post-attachment resistance in 29Aw was further supported by fewer (22%) Striga-host vascular connections in 29Aw compared to 79% in SOSAT-C88-P10. Together, these findings demonstrate that 29Aw harbors both pre- and post-attachment resistance mechanisms against S. hermonthica.

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