DIFFERENTIAL EXPRESSION OF NODULE-SPECIFIC (NODULIN) GENES IN THE INFECTED, UNINFECTED AND CORTICAL-CELLS OF SOYBEAN (GLYCINE-MAX) ROOT-NODULES

The expression of nodule-specific (nodulin) genes during soybean nodule development the sites of the expression in the nodule were investigated. Total or poly(A+) RNA were isolated from the infected uninfected cell protoplasts the cortex of nodules as well as from uninfected roots whole nodules from hydroponically grown plants. The products of in vitro translation of isolated RNA were analyzed by two-dimensional gel electrophoresis. The expression of more than 20 nodulin genes was detected in mature root nodules. At least 3 nodulin genes coding for N-75, N-75' and N-38 were expressed within 7 days after Bradyrhizobium inoculation. Five additional nodulin genes and at least a part of leghemoglobin (Lb) genes were expressed by 10 days. After 13 days, when nitrogenase activity was first detected, the majority of the nodulin genes was expressed at significant levels. None of the nodulin genes detected had a transient expression pattern. Early nodulin genes including N-75 and N-75' were intensely expressed even in nodules from 43 day-old plants. The most abundant nodulin mRNAs in the mature nodules were those of leghemoglobin (Lb), N-24 and N-24'. The latter two were present only in the infected cells. Early nodulin genes were expressed specifically in the uninfected cells and/or in the nodule cortex. The mRNAs of N-75 and N-75' were both detected specifically in the cortex. The mRNAs of N-38, N-38' and N-44 were present in both the uninfected cells and cortex but not in the infected cells. The genes encoding Lb proteins were most abundantly expressed in the infected cells. However, weak but significant expression of Lb-genes were detected in the uninfected cells. © 1990, Gustav Fischer Verlag, Stuttgart. All rights reserved.