1a. Objectives (from AD-416)
Identify factors that explain differences in yield among lowbush blueberry clones. Compare high yielding clones to low yielding clones for several factors. Factors include average genetic similarity with neighbors and effects of relationship of parents in controlled crosses on fruit set, synchrony of flowering time with neighbors, freezing tolerance of closed flower buds and open flowers, floral morphological and physiological differences (nectar amounts) that might be more attractive to bees, signs of disease, etc.
1b. Approach (from AD-416)
Studies will focus on comparing high yielding clones to low yielding clones for several factors. Because V. angustifolium is predominantly outcrossing and self-fertility is poor due to early- acting inbreeding depression, one of the factors that will be investigated is genetic relationship with neighboring clones. EST-PCR markers will be used to genotype clones and determine relationship (genetic similarity) to other clones. Crosses will be made between high yielding clones and other clones in the field that have clearly different similarity values. The same will be done with low yielding clones. In this way, it will be determined if genetic relationship affects yield. In addition, 4-5 clones in the immediate vicinity of each high and low yielder will be genotyped. The average similarity value between each focal high and low yielder and its neighbors will be determined and compared. Other factors will be compared between high and low yielding clones including synchrony of flowering time with neighbors, freezing tolerance of closed flower buds and open flowers, flower morphology, signs of disease, etc.
3. Progress Report
About 2/3 of commercial blueberry production is from improved cultivars of highbush blueberry (Vaccinium corymbosum), whereas about 1/3 is from managed, wild stands of lowbush blueberry (V. angustifolium). Lowbush blueberry grows in a patchwork or mosaic pattern of individuals referred to as clones. Variation among clones is very high with adjacent clones showing as much as 12-15 fold differences in berry yield. There has been no substantial breeding for improvement or genetic studies conducted on lowbush blueberry. Thus, the focus of this research is to use DNA markers to identify genetic factors responsible for differences in yield among lowbush clones. Molecular markers developed from highbush blueberry termed EST-PCR (Expressed Sequence Tag-Polymerase Chain Reaction) markers were tested in lowbush blueberry and shown to be very effective at genetic fingerprinting and relationship studies. The markers successfully discriminated between adjacent clones in the field. Thus, the markers will be useful to scientists in future research to understand the genetic structure of wild fields of lowbush blueberry. Progress was monitored by the ADODR through meetings, phone calls, and e-mails to exchange data and discuss research plans.