Changes in the sensitivity of parasitic weed seeds to germination stimulants

2004 ◽  
Vol 14 (4) ◽  
pp. 335-344 ◽  
Author(s):  
Radoslava Matusova ◽  
Tom van Mourik ◽  
Harro J. Bouwmeester
Keyword(s):  
Rapid Change ◽  
Field Conditions ◽  
Striga Hermonthica ◽  
Wild Plant ◽  
Parasitic Weed ◽  
Germination Stimulant ◽  
Secondary Dormancy ◽  
Short Period ◽  
Weed Seeds ◽  
Germination Stimulants

The effects of preconditioning temperature and preconditioning period on the sensitivity of parasitic weed seeds to the synthetic germination stimulant GR24 were studied under laboratory and field conditions. The temperature during preconditioning ofOrobanche cumanaandStriga hermonthicaseeds strongly affected the responsiveness of the seeds to the applied germination stimulant. Preconditioning at an optimal temperature (21°C forO. cumanaand 30°C forS. hermonthica) rapidly released dormancy and increased the sensitivity to GR24 by several orders of magnitude. After reaching maximum sensitivity, prolonged preconditioning rapidly induced secondary dormancy, i.e. decreased sensitivity ofO. cumanaandS. hermonthicato GR24. The rapid change in sensitivity of preconditioned seeds to germination stimulants during prolonged preconditioning was particularly visible at low concentrations of GR24. GR24 at higher concentrations (0.1 and 1 mg l1) usually induced high germination of both species, regardless of the preconditioning period. The striking similarities between the response of parasitic weed seeds to GR24, described here, and results in the literature on non-parasitic wild plant seeds are discussed. Our results show that parasitic weed seeds are highly sensitive to the germination stimulant for a short period of time only, and then enter into secondary dormancy relatively quickly. The similar germination pattern ofS. hermonthicaseeds preconditioned for prolonged periods of time under laboratory and field conditions suggests that the mechanism observed is of ecological significance.

scholarly journals Genomics of sorghum local adaptation to a parasitic plant

2019 ◽  
Author(s):  
Emily S. Bellis ◽  
Elizabeth A. Kelly ◽  
Claire M. Lorts ◽  
Huirong Gao ◽  
Victoria L. DeLeo ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Local Adaptation ◽  
Striga Hermonthica ◽  
Wild Plant ◽  
Parasitic Weed ◽  
Genome Wide ◽  
Staple Crop ◽  
Term Maintenance ◽  
Maintenance Of Diversity

ABSTRACTHost-parasite coevolution can maintain high levels of genetic diversity in traits involved in species interactions. In many systems, host traits exploited by parasites are constrained by use in other functions, leading to complex selective pressures across space and time. Here, we study genome-wide variation in the staple crop Sorghum bicolor (L.) Moench and its association with the parasitic weed Striga hermonthica (Delile) Benth., a major constraint to food security in Africa. We hypothesize that geographic selection mosaics across gradients of parasite occurrence maintain genetic diversity in sorghum landrace resistance. Suggesting a role in local adaptation to parasite pressure, multiple independent loss-of-function alleles at sorghum LOW GERMINATION STIMULANT 1 (LGS1) are broadly distributed among African landraces and geographically associated with S. hermonthica occurrence. However, low frequency of these alleles within S. hermonthica-prone regions and their absence elsewhere implicate potential tradeoffs restricting their fixation. LGS1 is thought to cause resistance by changing stereochemistry of strigolactones, hormones that control plant architecture and belowground signaling to mycorrhizae and are required to stimulate parasite germination. Consistent with tradeoffs, we find signatures of balancing selection surrounding LGS1 and other candidates from analysis of genome-wide associations with parasite distribution. Experiments with CRISPR-Cas9 edited sorghum further indicate the benefit of LGS1-mediated resistance strongly depends on parasite genotype and abiotic environment and comes at the cost of reduced photosystem gene expression. Our study demonstrates long-term maintenance of diversity in host resistance genes across smallholder agroecosystems, providing a valuable comparison to both industrial farming systems and natural communities.SIGNIFICANCE STATEMENTUnderstanding co-evolution in crop-parasite systems is critical to management of myriad pests and pathogens confronting modern agriculture. In contrast to wild plant communities, parasites in agricultural ecosystems are usually expected to gain the upper hand in co-evolutionary ‘arms races’ due to limited genetic diversity of host crops in cultivation. Here, we develop a framework to characterize associations between genome variants in global landraces (traditional varieties) of the staple crop sorghum with the distribution of the devastating parasitic weed Striga hermonthica. We find long-term maintenance of diversity in genes related to parasite resistance, highlighting an important role of host adaptation for co-evolutionary dynamics in smallholder agroecosystems.

La relation entre le Striga hermonthica et ses hôtes: une synthèse

1996 ◽  
Vol 74 (7) ◽  
pp. 1119-1137 ◽  
Author(s):  
Alain Olivier
Keyword(s):  
Control Method ◽  
Resistance Mechanisms ◽  
Striga Hermonthica ◽  
Effective Control ◽  
Parasitic Weed ◽  
New Methods ◽  
Interaction Control ◽  
Host Root ◽  
Germination Stimulants ◽  
Host Parasite

The parasitic weed Striga hermonthica causes considerable yield losses in maize, pearl millet, and sorghum in Africa. The extent of the damage caused to crops is related to their close interaction with the parasite. The S. hermonthica seed germinates in response to germination stimulants exuded by cereal roots. The rootlet extremity then turns into a haustorium that attaches itself to the host root and penetrates its tissue. In this manner, a connection is established between the vascular systems of both plants, allowing absorption of water, minerals, and organic compounds that are essential for the parasite's development. S. hermonthica also affects the host's metabolism and photosynthesis. No effective control method against the parasite is available for the African peasants. The utilization of germination stimulants and herbicides, the rotation practice, and intercropping as well as biological control and varietal selection have given disappointing results so far. A better understanding of host resistance mechanisms is necessary to develop new methods for the control of the parasite. Keywords: Striga hermonthica, germination, haustorium, host–parasite interaction, control methods, resistance.

Agronomic, breeding, and biotechnological approaches to parasitic plant management through manipulation of germination stimulant levels in agricultural soils

Botany ◽  
2011 ◽  
Vol 89 (12) ◽  
pp. 813-826 ◽  
Author(s):  
M. Fernández-Aparicio ◽  
J.H. Westwood ◽  
D. Rubiales
Keyword(s):  
Mycorrhizal Fungi ◽  
Agricultural Soils ◽  
Host Recognition ◽  
Plant Management ◽  
Parasitic Weed ◽  
Germination Stimulant ◽  
New Class ◽  
Agronomic Practices ◽  
Number Of Plant Species

A number of plant species have adapted to parasitize other plants, and some parasitic species pose severe constraints to major crops. The role of strigolactones and other metabolites present in host root exudates as germination stimulants for weedy root parasitic weed seeds has been known for the last 40 years. Recently, the ecological and developmental roles of strigolactones have been clarified by the discovery that they are a new class of plant hormone that controls shoot branching and serve as host recognition signals for mycorrhizal fungi. Parasitic plants also recognize these chemicals and use them to coordinate their life cycle with that of their host. Here we review agronomic practices that use parasitic germination stimulant production as a target for manipulation to control parasitic weeds.

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.

Long-term management of the parasitic weed Striga hermonthica: Strategy evaluation with a population model

2007 ◽  
Vol 26 (3) ◽  
pp. 219-227 ◽  
Author(s):  
P.R. Westerman ◽  
A. van Ast ◽  
T.J. Stomph ◽  
W. van der Werf
Keyword(s):  
Population Model ◽  
Striga Hermonthica ◽  
Parasitic Weed ◽  
Strategy Evaluation ◽  
Term Management

scholarly journals Genomic regions influencing resistance to the parasitic weed Striga hermonthica in two recombinant inbred populations of sorghum

2004 ◽  
Vol 109 (5) ◽  
pp. 1005-1016 ◽  
Author(s):  
B. I. G. Haussmann ◽  
D. E. Hess ◽  
G. O. Omanya ◽  
R. T. Folkertsma ◽  
B. V. S. Reddy ◽  
...  
Keyword(s):  
Recombinant Inbred ◽  
Striga Hermonthica ◽  
Parasitic Weed ◽  
Genomic Regions ◽  
Inbred Populations

scholarly journals Secondary dormancy induction and release inBromus tectorumseeds: the role of temperature, water potential and hydrothermal time

2017 ◽  
Vol 27 (1) ◽  
pp. 12-25 ◽  
Author(s):  
K. K. Hawkins ◽  
P.S. Allen ◽  
S.E. Meyer
Keyword(s):  
Water Potential ◽  
Model Parameters ◽  
Hydrothermal Time ◽  
Primary Dormancy ◽  
Secondary Dormancy ◽  
Short Period ◽  
Dry Conditions ◽  
Time Parameters ◽  
Germination Timing ◽  
Dormancy Induction

AbstractSeeds of the winter annualBromus tectorumlose primary dormancy in summer and are poised to germinate rapidly in the autumn. If rainfall is inadequate, seeds remain ungerminated and may enter secondary dormancy under winter conditions. We quantified conditions under which seeds enter secondary dormancy in the laboratory and field and also examined whether contrastingB. tectorumgenotypes responded differently to dormancy induction cues. The study also extends previous hydrothermal time models for primary dormancy loss and germination timing inB. tectorumby using similar models to account for induction and loss of secondary dormancy. Maximum secondary dormancy was achieved in the laboratory after 4 weeks at –1.0 MPa and 5°C. Seeds in the field became increasingly dormant through exposure to temperatures and water potentials in this range, confirming laboratory results. They were released from dormancy through secondary after-ripening the following summer. Different genotypes showed contrasting responses to dormancy induction cues in both laboratory and field. To examine secondary dormancy induction and release in the field in terms of hydrothermal time parameters, we first created a model that allowed mean base water potential (Ψb(50)) to vary while holding other hydrothermal time parameters constant, as in models for primary dormancy loss under dry conditions. The second model allowed all three model parameters to vary through time, to account for changes (e.g. hydrothermal time accumulation) that could occur simultaneously with dormancy induction in imbibed seeds. Shifts in Ψb(50) could explain most changes in dormancy status for seeds retrieved from the field, except during the short period prior to dormancy induction, when hydrothermal time was accumulating. This study illustrates that hydrothermal modelling, and specifically changes in Ψb(50), can be used to characterize secondary dormancy induction and loss inB. tectorum.

scholarly journals A full-length enriched cDNA library and expressed sequence tag analysis of the parasitic weed, Striga hermonthica

2010 ◽  
Vol 10 (1) ◽  
pp. 55 ◽  
Author(s):  
Satoko Yoshida ◽  
Juliane K Ishida ◽  
Nasrein M Kamal ◽  
Abdelbagi M Ali ◽  
Shigetou Namba ◽  
...  
Keyword(s):  
Cdna Library ◽  
Expressed Sequence Tag ◽  
Full Length ◽  
Striga Hermonthica ◽  
Parasitic Weed ◽  
Expressed Sequence Tag Analysis ◽  
Expressed Sequence

Germination of Orobanche crenata seeds, as influenced by conditioning temperature and period

1993 ◽  
Vol 71 (6) ◽  
pp. 786-792 ◽  
Author(s):  
M. J. van Hezewijk ◽  
A. P. van Beem ◽  
J. A. C. Verkleij ◽  
A.H. Pieterse
Keyword(s):  
Key Words ◽  
Optimum Temperature ◽  
Orobanche Crenata ◽  
Parasitic Weed ◽  
Secondary Dormancy ◽  
Conditioning Period ◽  
Conditioning Temperature ◽  
Seeds Germination ◽  
Tetrazolium Test

The effects of conditioning temperature and length of the conditioning period on germination of seeds of the parasitic weed Orobanche crenata were investigated in vitro. Seed samples from Syria and Egypt, collected in various years, were compared. Optimum temperature for conditioning was 15–20 °C for Syrian seeds and 20 or 15–20 °C for Egyptian seeds. At 20 °C a conditioning period of 18 days was required for maximum germination. When conditioning at 20 °C was prolonged beyond 7 weeks, germination decreased. This effect was more pronounced for Egyptian seeds than for Syrian seeds. Germination of Syrian seeds was strongly reduced after conditioning for more than 4 weeks at 15 or 10 °C. A stepwise decrease in temperature during conditioning did not enhance this effect. The results of a tetrazolium test indicated that the seeds most probably did not die but developed secondary dormancy. Key words: Orobanche, germination, conditioning, temperature, dormancy.

scholarly journals Differential Activity of Striga hermonthica Seed Germination Stimulants and Gigaspora rosea Hyphal Branching Factors in Rice and Their Contribution to Underground Communication

PLoS ONE ◽  
2014 ◽  
Vol 9 (8) ◽  
pp. e104201 ◽  
Author(s):  
Catarina Cardoso ◽  
Tatsiana Charnikhova ◽  
Muhammad Jamil ◽  
Pierre-Marc Delaux ◽  
Francel Verstappen ◽  
...  
Keyword(s):  
Seed Germination ◽  
Striga Hermonthica ◽  
Hyphal Branching ◽  
Gigaspora Rosea ◽  
Underground Communication ◽  
Germination Stimulants
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