Soybean Matrix Metalloproteinase <Emphasis Type="Italic">Gm2-MMP</Emphasis> Relates to Growth and Development and Confers Enhanced Tolerance to High Temperature and Humidity Stress in Transgenic <Emphasis Type="Italic">Arabidopsis</Emphasis>

Matrix metalloproteinases (MMPs) are a family of zinc-dependent endopeptidases. It has been speculated that plant MMPs are involved in plant growth, development, and stress response. However, the biological function of MMPs in higher plants still remains elusive. In the present study, a MMP gene Gm2-MMP was isolated and characterized. It encoded a 357 amino acids protein and contained a common domain structure of MMPs. Subcellular localization of Gm2-MMP-GFP fusion protein indicated that Gm2-MMP was located in plasma membrane. Gm2-MMP was found to show higher expression levels in mature seeds, mature leaves, or old leaves than in other organs and was continuously expressed from seed development to maturation stage. Additionally, Gm2-MMP participated in response to HTH stress in leaves and developing seeds (R7 period) of soybean. The overexpression of Gm2-MMP in Arabidopsis affected the growth and development of leaves, enhanced the tolerance to HTH stress in leaves and developing seeds, and improved the vitality of seed. Twenty-eight candidate proteins interacted with Gm2-MMP were identified from the cDNA library of soybean developing seed under HTH stress by yeast two-hybrid (Y2H) screen. Our results suggested that Gm2-MMP is related to growth and development and confers enhanced HTH stress tolerance in plants. This will be helpful for us in further understanding of the biological functions of MMP family in plant.