Gender determination, the key to germplasm utilization in strawberry

1
Gender determination, the key to germplasm
utilization in strawberry

• Dr. Tia-Lynn Ashman, Univ. of Pittsburgh
• Dr. Kimberly Lewers, USDA-ARS Fruit Lab
• Dr. Dorrie Main, Clemson Univ.

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Gender in Strawberries

• Hermaphroditic (Hermaphrodite)
• F. X ananassa
• F. vesca
• Gynodioecious (Hermaphrodite/Female)
• F. virginiana
• Dioecious (Male/Female)
• F. chiloesis
• Trioecious (Male/Hermaphrodite/Female)
• F. orientalis

Staudt 1989
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Understanding gender determination is important
because

• Wild germplasm is an important resource
• Wild progenitors are gender dimorphic
• Marker assisted selection would allow for
• Selection for high yield
• Introgression of other desirable traits while
  selection against undesirable traits (sterility)

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Objective

• Characterize gender-related genes in octoploid
  wild Fragaria via QTL mapping
• Determine similarity between Fragaria and peach
  genomes wrt gender genes

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Gender-qualitative
Qualitative Phenotype Putative Genotype

• Fh or Fm
• hh or hm
• mm

• Female
• High fruit production
• Lack pollen production
• Hermaphrodite
• Produces pollen
• Produces fruit
• Male
• Produces pollen
• Lacks fruit

Valleau 1923, Ahmadi Bringhurst 1989
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Gender- quantitative

• Fruit set ability (fruits/flowers)
• high (strong )
• variable/inconsistent (weak)
• no fruit (functional male staminate)
• Achenes/fruit
• Ovules/flower
• Anthers/flower
• Pollen/anther
• Flowers/plant

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Mapping populations
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Gender Assessment
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Molecular Approach

• Microsatellites (SSRs)
• gt5000 sequences in GenBank
• Candidate gender-related genes (SCAR)
• Tasselseed2 (maize) homolog in Strawberry

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Expected Outcomes

• Genetic map of gender QTL
• Determination of how gender is inherited (one,
  two, linked loci?)
• Gender-characterized Fragaria genotypes deposited
  in Germplasm Repository
• Fragaria-derived SSR, SCAR and bridging markers
  deposited in GenBank