Electronic Thesis and Dissertation Repository


Master of Science




Hannoufa, Abdelali

2nd Supervisor

Macfie, Sheila



Heat stress negatively impacts plant development by disrupting regular plant functions, including molecular, physiological and anatomical processes, reducing crop production. Alfalfa (Medicago sativa) is an important forage crop and developing abiotic stress resistant cultivars would help mitigate crop losses. Members of the miR156 family regulate SPL genes, impacting plant growth and development and are involved in stress response. Here, alfalfa with miR156 overexpression (miR156OE) and SPL13 RNAi knockdown (SPL13i) showed increased tolerance to heat stress (40°C) while SPL9 RNAi alfalfa did not. Heat-stressed miR156OE and SPL13i plants had increased antioxidant levels, including anthocyanins. Additionally, genes associated with miR156 involved in hormone and antioxidant biosynthesis were differentially regulated under heat stress in transgenic alfalfa. These results demonstrate that miR156 contributes to heat stress tolerance in alfalfa at least partially by silencing SPL13 and suggest SPL13 could be useful for improving abiotic stress tolerance in alfalfa and potentially other crops.

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