Submitted to: The Plant Cell
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/3/2014
Publication Date: 7/8/2014
Publication URL: http://handle.nal.usda.gov/10113/59380
Citation: Ping, J., Liu, Y., Sun, L., Zhao, M., Li, Y., She, M., Sui, Y., Lin, F., Liu, X., Tang, Z., Nguyen, H., Tian, Z., Qiu, L., Nelson, R.L., Clemente, T.C., Specht, J.E., Ma, J. 2014. Dt2 is a gain-of-function MADS-Domain factor gene that controls semi-determinacy in soybean. The Plant Cell. DOI/10.1105/tpc.114.126938. Interpretive Summary: Soybean stem growth habit is a critical agronomic trait that affects the plant's overall yield potential and adaptation to diverse environments. Based on the timing of the termination of apical stem growth and the initiation of terminal flowering, most soybean cultivars can be classified into two categories, commonly known as determinate and indeterminate controlled by Dt1 gene. A second gene, Dt2, produces plants that are intermediate in appearance to determinate and indeterminate types and are commonly called semi-determinate. Few soybean genes have as large an effect on soybean plants as these genes so knowing what these genes are and how they function is very important. Our research group previously identified the Dt1 gene. In this research we cloned the Dt2 gene and discovered that is related to other known genes that affect flowering; however, it has a very different genetic mechanism. It may be a recent mutation and unlike many mutations that eliminate a genetic function, this mutation produces a new function. This research will be of use to plant geneticists.
Technical Abstract: Similar to Arabidopsis, the wild soybean (Glycine soja) and many soybean (Glycine max) cultivars exhibit indeterminate stem growth controlled by a gene Dt1 – the functional counterpart of the Arabidopsis TFL1. Mutations in TFL1 and Dt1 both result in the shoot apical meristem (SAM) switching from vegetative to reproductive state to initiate terminal flowering and thus produce determinate stems. A second soybean gene (Dt2) regulating stem growth was identified, which, in the presence of Dt1, produces semi-determinate plants with terminal racemes similar to those observed in determinate plants. Here, we report positional cloning and characterization of Dt2, a dominant MADS domain factor gene closely related to the AP1/SQUA subfamily that includes floral meristem (FM) identity genes AP1, FUL, and CAL in Arabidopsis. Unlike AP1, whose expression is limited to FMs in which the expression of TFL1 is repressed, Dt2 appears to repress the expression of Dt1 in the SAMs to promote early conversion of the SAMs into reproductive inflorescences. Given that Dt2 is not the gene most closely related to AP1, and that semi-determinacy is rarely seen in wild soybeans, Dt2 appears to be a recent gain-of-function mutation, which has modified the genetic pathways controlling the stem growth habit in soybean.