In situ hybridization of two nodule-specific gene products from yellow lupin

We have applied in situ hybridization technique to examine the expression of two tissue-specific plant genes represented by cDNA clones: pLN-13 and pLN-50 during the symbiosis of Lupinus luteus with Bradyrhizobium lupini. Both genes are expressed in root nodules and their transcripts are restricted to the infected zone of the nodule as revealed with 35S-or 3H-labelled antisense RNA probes. The number of grains over bacteroid-containing cells after hybridization with 3H-labelled probes differed during three tested phases of nodule development: at the 14th, 21st and 28th day after the infection with B. lupini. As control, apical root meristems and segments of root hair zones of uninfected plants were used for incubation with RNA of either sense or antisense orientation preceded by RNAse A digestion. The data obtained confirm that both genes are organ-specific and reveal their developmentally regulated expression pattern during the course of root nodule morphogenesis.