ARS | Publication request: Longevity of crapemyrtle pollen stored at different temperatures

Submitted to: Scientia Horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 16, 2012
Publication Date: April 1, 2012
Citation: Akond, G., Pounders Jr, C.T., Blythe, E., Wang, X. 2012. Longevity of crapemyrtle pollen stored at different temperatures. Scientia Horticulturae. 139:53-57.

Interpretive Summary: The ability to store crapemyrtle pollen is critical to plant improvement programs when individuals to be hybridized do not flower concurrently or these individuals are geographically separated. Pollen storage has the potential to improve breeding through germplasm exchange and preservation to increase genetic diversity . The objective of the study was to determine appropriate temperature parameters for storage of crapemyrtle pollen by evaluating pollen storage of seven crapemyrtles clones (five species and two interspecific hybrids) representative of germplasm commonly used in ornamental breeding programs. Pollen of all 7 clones lost viability after 7 days of storage at room temperature (23 °C). Storage at 4 °C prolonged the longevity of pollen (period of time over which the pollen retains its viability, i.e. germinability and fertility) for all clones studied, with L. speciosa and L. 'Wichita' being most responsive. Pollen longevity of the interspecific hybrids, L. 'Cheyenne' and L. 'Wichita', was not significantly extended when stored at -20 °C and -80 °C in comparison with storage at 4 °C. No statistical differences were observed between storage at -20 °C and -40 °C for L. fauriei 'Kiowa', L. limii, L subcostata, and L. speciosa. Only L. indica 'Catawba' showed increased duration of pollen viability as the storage temperature was decreased to -80 °C. Storage of viable crapemyrtle pollen for no more than 75 to 105 d is adequate for allowing breeders to efficiently carry out hybridization of germplasm flowering at different times or in widely separated locations.

Technical Abstract: Temperatures for storage of crapemyrtle (Lagerstroemia app.) pollen over time were studied using clones of two interspecific hybrids (L. 'Cheyenne' and L. 'Wichita') and five species (L. indica 'Catawba', L. subcostata (NA 40181), L. limii, L. speciosa, and L. fauriei 'Kiowa'). Pollen samples were stored at room temperature (23±1 °C), 4 °C, -20 °C and -80 °C. Germination of pollen samples was examined at 0, 7, 15, 45, 75, or 105 d of storage (DOS) and data were analyzed using linear models. Fresh (0 DOS) pollen of L. 'Cheyenne' showed the highest germination (80%). Among the other clones, pollen germination at 0 DOS ranged from 44% (L. speciosa) to 77% (L. fauriei 'Kiowa'). Pollen of all cultivars lost their viability within 7 DOS at room temperature. Overall, this study indicated that Lagerstroemia pollen is best maintained over time when pollen is stored under refrigeration, with a storage temperature of -20 °C often being preferable to 4 °C. Lowering the storage temperature to -80 °C is generally unnecessary, but not deleterious to pollen germination. Storage of viable crapemyrtle pollen for no more than 75 to 105 d is adequate for allowing breeders to efficiently carry out hybridization of germplasm flowering at different times or in widely separated locations.