Connecting the dots: How microRNA156 regulates multiple traits in alfalfa

Citation

Hannoufa A., Feyissa B, Arshad M, Gao R, Matthews C, Aung B, Amyot L (2018) Connecting the dots: How microRNA156 regulates multiple traits in alfalfa, The 2018 Meeting of the Canadaian Association for Plant Biotechnology, Saskatoon, SK, May 14-18, 2018

Plain language summary

Alfalfa (Medicago sativa L.) is the most productive perennial legume in Canada, where it is grown mostly as a forage crop. Despite its high commercial value, alfalfa productivity is hampered by a number of factors, especially environmental stress. MicroRNA156 (miR156) exerts its function by silencing genes encoding members of the SPL transcription factor family, which in turn regulate downstream genes to affect a multitude of traits in plants. We have identified seven SPL genes (SPL2, SPL3, SPL4, SPL6, SPL12 and SPL13) that were silenced by miR156 via transcript cleavage in alfalfa. Alfalfa plants overexpressing miR156 (miR156+) exhibited several positive traits, including an increase in vegetative biomass, delayed flowering, enhanced shoot branching, improved cell wall composition, increased root length and root regeneration capacity, and enhanced abiotic (drought, heat and salinity) tolerance. Moreover, nodulation and nitrogen fixation were also enhanced in miR156+ plants. A central player in the alfalfa miR156/SPL network is SPL13, as overexpression and silencing experiments provided evidence about its essential role in regulating lateral branch development, leaf morphology, flowering time, and drought resilience. Our research aims to elucidate the function of each of the miR156-targeted SPL (and non-SPL) genes in alfalfa and associate them to the traits affected by miR156. The long term goal of this research is to develop tools for biotechnological improvement of alfalfa not only as forage crop for livestock feed, but also as a potential bioenergy crop for cellulosic biofuel applications.

Abstract

Alfalfa (Medicago sativa L.) is the most productive perennial legume in Canada, where it is grown mostly as a forage crop. Despite its high commercial value, alfalfa productivity is hampered by a number of factors, especially environmental stress. MicroRNA156 (miR156) exerts its function by silencing genes encoding members of the SPL transcription factor family, which in turn regulate downstream genes to affect a multitude of traits in plants. We have identified seven SPL genes (SPL2, SPL3, SPL4, SPL6, SPL12 and SPL13) that were silenced by miR156 via transcript cleavage in alfalfa. Alfalfa plants overexpressing miR156 (miR156+) exhibited several positive traits, including an increase in vegetative biomass, delayed flowering, enhanced shoot branching, improved cell wall composition, increased root length and root regeneration capacity, and enhanced abiotic (drought, heat and salinity) tolerance. Moreover, nodulation and nitrogen fixation were also enhanced in miR156+ plants. A central player in the alfalfa miR156/SPL network is SPL13, as overexpression and silencing experiments provided evidence about its essential role in regulating lateral branch development, leaf morphology, flowering time, and drought resilience. Our research aims to elucidate the function of each of the miR156-targeted SPL (and non-SPL) genes in alfalfa and associate them to the traits affected by miR156. The long term goal of this research is to develop tools for biotechnological improvement of alfalfa not only as forage crop for livestock feed, but also as a potential bioenergy crop for cellulosic biofuel applications.

Publication date

2018-05-17