Agriculture

Tyler Hacking, Jonathan Wasden and Dr. Michael Stevens (Utah Valley University)
Faculty Advisor: Stevens, Michael (Science, Biology)

Abstract:

Plant growth can be affected by both genes and the environment. To test genetic effects on growth we used two varieties of lettuce. To test environmental effects on growth, we used four different water treatments. We were interested in the main effects of genes and the environment and also in their interaction. In other words, is the effect of water treatment different across two lettuce varieties? Two varieties of Lactuca sativa were cultivated in a growth chamber in pots using vermiculite as the growth medium. The two varieties were treated with four types of water: tap, tap-aerated, reverse osmosis, and reverse-osmosis-aerated throughout the experiment. Aeration was accomplished using both surface aeration (waterfall and vortex) and sub-surface aeration using submerged waterstones. All plants were fertilized using 8-15-36 (N-P-K) water-soluble lettuce fertilizer powder plus trace minerals by Greenway Biotech, Inc. The plants were harvested and dried to a constant weight for analysis of biomass. We observed varietal differences in growth with the Buttercrunch variety producing 145% more biomass than the Butterhead variety (p < 0.001). The water treatments affected growth, with the plants watered with tap water producing 31% more biomass than the plants watered with reverse-osmosis water (p < 0.001). The other two water treatments (tap-aerated and reverse-osmosis-aerated) were intermediate between the tap-watered plants and the reverse-osmosis-watered plants in terms of biomass. Finally, we observed a variety-by-environment interaction such that the Buttercrunch showed a marked response to water treatment whereas the Butterhead was only minimally affected by water treatment (p < 0.001). The Buttercrunch produced more biomass than the Butterhead because of its shorter life cycle. By the end of the experiment, the Buttercrunch plants were already bolting and producing flowers. This could also explain why the Buttercrunch was more responsive to differences in water treatments.

Waldron, Connor; Moley, Laura; Isom, S. Clay (Utah State University)
Faculty Advisor: Isom, S. Clay (College of Agriculture and Applied Sciences; Animal, Dairy, and Veterinary Sciences Department)

In vitro maturation (IVM) is a process that immature oocytes undergo before in vitro fertilization is performed. During IVM, immature oocytes are extracted through aspiration from follicles and receive the necessary hormones to resume meiosis in culture. Success rate of IVM is significantly lower compared to in vivo maturation of oocytes. Oocytes selected for IVM are extracted from small ovarian follicles (1-3mm), which are 4-6 weeks away from complete maturation and subsequent ovulation. During that period, the DNA of the oocyte is undergoing the process of DNA methylation, the addition of a methyl group to cytosines within a CpG context. DNA methylation is an epigenetic change that causes modification to gene expression where methylated gene promoters turn off gene expression. Proper oocyte gene expression is very important in the development of a healthy embryo. Incomplete methylation of aspirated oocytes may be another factor contributing to the low success rates of IVM. We hypothesize that there is a difference in the amount of methylation between oocytes from small ovarian follicles that are further from natural ovulation and oocytes from large ovarian follicles which are developmentally closer to ovulation, with higher levels of methylation in oocytes from large ovarian follicles. To test our hypothesis, large porcine ovarian follicles (7mm and larger) and small porcine ovarian follicles (1-3mm) will be aspirated for ovaries. The oocytes will be stained the two stains, one to visualize the nucleus of the oocyte indicating the presence of DNA and the other to visualize DNA methylation. Fluorescent images will be taken of the oocytes, and the small and large follicle oocyte groups will be compared for genome wide methylation levels.