miR156/SPL network negatively regulates aluminum stress tolerance in Medicago sativa


Allam G, Papadopoulos Y, Bernards BA, Hannoufa A (2021) miR156/SPL network negatively regulates aluminum stress tolerance in Medicago sativa. The 2021 Annual General Meeting of the Canadian Society of Plant Physiologists (virtual), Saskatoon, SK, June 7-10, 2021


Aluminum (Al) toxicity is a serious environmental stress facing global crop production in acidic soils. Al toxicity triggers oxidative stress, contributing to extensive losses in alfalfa. Alfalfa is the most extensively cultivated legume forage crop worldwide, necessitating development of crops tolerant to abiotic stress. Alfalfa improvement by conventional breeding is limited due to its polyploidy and allogamous reproduction, but new possibilities have arisen with the introduction of microRNAs as a breeding tool. microRNA156 (miR156), is highly conserved in plants and functions by downregulating SQUAMOSA-PROMOTER BINDING PROTEIN-LIKE (SPL) transcription factors. At least sixteen SPL genes are targeted for silencing by miR156 in alfalfa. SPLs further regulate the expression of a network of downstream genes that affect plant physiology and development through binding to gene promoters at a consensus DNA sequence known as the SPL Binding Domain (SBD). In this study, we determined the function of miR156 in regulating aluminum tolerance by investigating the phenotypic changes associated with altered expression of miR156. For this, we used three miR156 overexpression alfalfa plants to investigate miR156 function at the phenotypic level. We plan to conduct transcriptomic analysis of alfalfa roots to identify SPL genes and other downstream genes that are regulated in response to Al stress. Phenotypic analysis revealed that alfalfa plants with increased expression miR156 level had inhibited root growth and plant height under Al stress. Transcript analysis revealed that SPL13 is differentially regulated in response to Al stress. The current findings suggest that miR156 OE negatively regulates alfalfa’s response to Al by inhibiting root growth and plant height, potentially by regulating SPL13.

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