Lotus japonicus and Medicago truncatula are widely used as model legumes for studying root nodulation in symbiosis with rhizobia. L. japonicus is nodulated by Mesorhizobium loti and makes determinate nodules, whereas M. truncatula is nodulated by Sinorhizobium meliloti and makes indeterminate nodules. However, a grafted plant with a M. truncatula shoot and a L. japonicus root is nodulated by M. loti (top picture) and makes determinate nodules as shown by the globular shape (bottom-left picture: nodules) and the lack of a meristem (bottom-right picture: a section of a nodule through the parent root; blue staining indicates the presence of rhizobia due to X-Gal staining), indicating root control of nodule type and host-specificity in L. japonicus. (See Lohar and VandenBosch, pp. 1643-1650.)
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