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This article in CS

  1. Vol. 32 No. 1, p. 73-77
    Received: Jan 18, 1991

    * Corresponding author(s):
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Pollinator Effects on Crossing and Genetic Shift in a Three-Flower-Color Alfalfa Population

  1. J. J. Steiner ,
  2. P. R. Beuselinck,
  3. R. N. Peaden,
  4. W. P. Kojis and
  5. E. T. Bingham
  1. N atl. Forage Seed Production Res. Ctr., USDA-ARS, 3450 SW Campus Way, Corvallis, OR 97331
    P lant Genetics Unit, USDA-ARS, Columbia, MO 65211
    V egetable and Forage Crops Production, USDA-ARS, Prosser, WA 99530



Understanding insect pollinator preference for different alfalfa (Medicago sativa L.) flower colors is important to maintain the genetic composition of plant introductions, germplasms, genetic stocks, and cultivars. This study was conducted to determine whether crossing and the relative proportion of hybrids in a model three-flower-color marker system were affected by kind or combination of insect pollinators [honey bees (Apis mellifera L.), leafcutter bees (Megachile rotundata F.), or both bee species combined). A secondary objective was to determine whether actual expression of compatibility between flower color lines, as determined by hand crosses in the greenhouse, was altered by insect pollinator behavior in the field. Noninbred (S0) and slightly inbred (S1) populations of cream- (CRM), white- (WHT), and yellow- (YEL) colored flower markers were grown at Fresno, CA, and Prosser, WA. When self- or sib-pollinated, the flower colors of all parental strains were reproduced, while hybrids among the parental strains produced unique-colored progeny that allowed determination of the flower color parentage of each line. All pollinator treatments showed similar preferences for flower color (CRM > WHT > YEL) at both locations. Slight inbreeding resulted in more hybrids with WHT seed parents (P ≤ 0.001), and increased hybrid production by CRM and WHT with pollen from YEL (P ≤ 0.06 and 0.08, respectively). Bee behavior altered the proportion of hybrids produced in the mixed flower-color population from the expected line-cross compatibility. The location of seed production also interacted with bee preference for CRM and WHT flowers. Level of inbreeding, insect pollinator behavior, and location of production may interact and change the described levels of different flower-colored lines and result in genetic shifts in plant introductions, germplasms, genetic stocks, and cultivars.

Joint contribution of USDA-ARS and College of Agricultural and Life Sciences, Univ. of Wisconsin, Madison, WI, in cooperation with the NC-83 Regional Project.

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