Agrodiversity: Genetic Diversity in Crops and Cropping Systems

2006 ◽  
pp. 43-62
Keyword(s):  
Genetic Diversity ◽  
Cropping Systems

Patterns and drivers of genetic diversity and structure in the biological control parasitoid Habrobracon hebetor in Niger

2019 ◽  
Vol 109 (6) ◽  
pp. 794-811
Author(s):  
M. Garba ◽  
A. Loiseau ◽  
C. Tatard ◽  
L. Benoit ◽  
N. Gauthier
Keyword(s):  
Genetic Diversity ◽  
Biological Control ◽  
Mating System ◽  
Cropping Systems ◽  
Nonrandom Mating ◽  
Habrobracon Hebetor ◽  
Complementary Sex Determination ◽  
Genetic Diversity And Structure ◽  
Field Samples ◽  
Grain Stores

AbstractWhen a promising natural enemy of a key pest exists locally, it is a common practice in biological control (BC) to rear and release it for supplementary control in the targeted agroecosystem even though significant knowledge gaps concerning pre/post release may still exist. Incorporating genetic information into BC research fills some of these gaps. Habrobracon hebetor, a parasitoid of many economically important moths that infest stored and field crops worldwide is commonly used, particularly against the millet head miner (MHM), a key pest of millet in Sahelian countries. To advance our knowledge on how H. hebetor that occurs naturally in open-field cropping systems and grain stores as well as being mass-produced and released for MHM control, performs in millet agroecosystems in Niger we evaluated its population genetics using two mitochondrial and 21 microsatellite markers. The field samples were genetically more diverse and displayed heterozygote excess. Very few field samples had faced significant recent demographic bottlenecks. The mating system (i.e. nonrandom mating with complementary sex determination) of this species may be the major driver of these findings rather than bottlenecks caused by the small number of individuals released and the scarcity of hosts during the longlasting dry season in Niger. H. hebetor population structure was represented by several small patches and genetically distinct individuals. Gene flow occurred at local and regional scales through human-mediated and natural short-distance dispersal. These findings highlight the importance of the mating system in the genetic diversity and structure of H. hebetor populations, and contribute to our understanding of its reported efficacy against MHM in pearl millet fields.

Use of AFLP Markers to Assess Genetic Diversity in Palmer Amaranth (Amaranthus palmeri) Populations from North Carolina and Georgia

Weed Science ◽  
2013 ◽  
Vol 61 (1) ◽  
pp. 136-145 ◽  
Author(s):  
Aman Chandi ◽  
Susana R. Milla-Lewis ◽  
David L. Jordan ◽  
Alan C. York ◽  
James D. Burton ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
North Carolina ◽  
Total Variation ◽  
Significant Variation ◽  
Cropping Systems ◽  
Geographic Region ◽  
Palmer Amaranth ◽  
Aflp Markers ◽  
Amaranthus Palmeri ◽  
Management Approaches

Glyphosate-resistant Palmer amaranth is a serious problem in southern cropping systems. Much phenotypic variation is observed in Palmer amaranth populations with respect to plant growth and development and susceptibility to herbicides. This may be related to levels of genetic diversity existing in populations. Knowledge of genetic diversity in populations of Palmer amaranth may be useful in understanding distribution and development of herbicide resistance. Research was conducted to assess genetic diversity among and within eight Palmer amaranth populations collected from North Carolina and Georgia using amplified fragment length polymorphism (AFLP) markers. Pair-wise genetic similarity (GS) values were found to be relatively low, averaging 0.34. The highest and the lowest GS between populations were 0.49 and 0.24, respectively, while the highest and the lowest GS within populations were 0.56 and 0.36, respectively. Cluster and principal coordinate (PCO) analyses grouped individuals mostly by population (localized geographic region) irrespective of response to glyphosate or gender of individuals. Analysis of molecular variance (AMOVA) results when populations were nested within states revealed significant variation among and within populations within states while variation among states was not significant. Variation among and within populations within state accounted for 19 and 77% of the total variation, respectively, while variation among states accounted for only 3% of the total variation. The within population contribution towards total variation was always higher than among states and among populations within states irrespective of response to glyphosate or gender of individuals. These results are significant in terms of efficacy of similar management approaches both in terms of chemical and biological control in different areas infested with Palmer amaranth.

scholarly journals Genetic Diversity of Verticillium dahliae Populations From Olive and Potato in Lebanon

Plant Disease ◽  
2019 ◽  
Vol 103 (4) ◽  
pp. 656-667 ◽  
Author(s):  
Farah Baroudy ◽  
Alexander I. Putman ◽  
Wassim Habib ◽  
Krishna D. Puri ◽  
Krishna V. Subbarao ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Genetic Structure ◽  
Verticillium Dahliae ◽  
Cropping Systems ◽  
Genetic Relationships ◽  
Geographic Origin ◽  
Wide Distribution ◽  
Economic Losses ◽  
Source Population

Verticillium dahliae is widely distributed in potato and olive fields in Lebanon, causing serious economic losses. However, little is known about the inoculum source, population structure, and genetic diversity of the pathogen or the mechanisms of dissemination within Lebanon. To understand the population structure, a total of 203 isolates sampled from olive (n = 78) and potato (n = 125) were characterized for species, mating type, and race, and the genetic relationships were delineated using 13 microsatellite markers. All isolates except one from potato were V. dahliae, with 55.1 and 12.1% race 1, and 43.6 and 83.1% race 2 in olive and potato, respectively. The genetic structure of the studied population was best described by two large and two small clusters. Membership in the two large clusters was determined by the presence or absence of the effector gene Ave1. Furthermore, genetic structure was moderately associated with the host of origin but was weakly associated with the geographic origin. All but four isolates represented by three multilocus haploid genotypes were MAT1-2. This study identified a clear lack of gene flow between virulence genotypes of V. dahliae despite the proximity of these cropping systems and the wide distribution of genetic diversity among hosts and geographic regions in Lebanon.

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