Semester of Graduation

Fall 2021

Degree

Master of Science (MS)

Department

Plant Pathology and Crop Physiology

Document Type

Thesis

Abstract

RNA interference (RNAi) is a useful tool in gene characterization and its use is expanding into more practical fields. Two RNAi techniques were used in this case. The studies conducted in the chapter two use transgenic maize lines containing an RNAi construct targeting ZmPR10 to characterize its potential role in growth and development in response to salinity stress. T1 transgenic plants from events A44S1-35-3 and A44S1-3-4, which had significantly reduced ZmPR10 expression compared to the non-transgenic controls, showed no differences compared to the controls in heights after 30 and 60 days, nor did the T2 transgenic from these events plants significantly differ in days to anthesis from non-transgenic plants. T3 transgenic lines from event A44S1-35-3 that had the highest suppression of ZmPR10 in roots showed insensitivity to salt stress with little to no change in root fresh and dry weights and root lengths. Trangenic T3 lines from event A44S1-35-3 with high ZmPR10 suppression in leaves showed significant changes in leaf lengths under salt stress. Transgenic T4 seedlings had significantly lower root and shoot weights when compared to the non-transgenic control seedlings under salt stress, and the T4 lines derived from T3 parents with high suppression of ZmPR10 in shoots had significantly higher root-to-shoot ratios than non-transgenic control seedlings. In chapter three, exogenous application of in vitro synthesized dsRNAs that target different regions of the causal gene of haploid induction MATRILINEAL1 /NOT LIKE DAD/Zea mays PATATIN-LIKE PHOSPHOLIPASE A1 (MTL/NLD/ZmPLA1) was attempted to improve haploid induction rates (HIR) in maize maternal haploid inducer lines (HIL). Four dsRNA products were used to treat HIL pollen in vitro and to treat crosses in situ. HIL pollen treated with dsRNA in vitro led to an apparent increase in mtl/nld/zmpla1 expression when compared to control treatments. The reason for such unexpected change is still unclear. Treatment of pollen with dsRNA during pollination led to a reduction in overall kernel setting without a significant increase in HIR in the resulting crosses. The study using transgenic RNAi lines targeting ZmPR10 indicates it likely plays a role in salinity stress response and early plant growth and development, and future studies using these lines should be performed to characterize the role of ZmPR10 in response to other stresses and phytohormones. The study attempting to utilize exogenous dsRNA to suppress mtl/nld/zmpla1 and increase HIRs indicated that some further optimization of treatment conditions, including the amount of dsRNAs applied, will be necessary before it can be determined whether in vitro application of dsRNA during pollination can be used to increase HIR or not.

Date

11-18-2021

Committee Chair

Chen Zhi-Yuan

DOI

10.31390/gradschool_theses.5472

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