ACCUMULATION OF TRANSCRIPTS ENCODING A LIPID TRANSFER-LIKE PROTEIN DURING DEFORMATION OF NODULATION-COMPETENT VIGNA-UNGUICULATA ROOT HAIRS

A cDNA library was constructed from RNA of Vigna unguiculata root hair s harvested 1 day and 4 days after inoculation with Rhizobium sp. NGR2 34. A heterologous probe was used to identify a cDNA clone, the predic ted 99-amino-acid sequence of which shares homology with a nonspecific lipid transfer protein (LTP) of Hordeum vulgare. Other characteristic s, including an estimated molecular weight of 10.4 kD, an isoelectric point of 8.6, and a signal peptide with a hydrophobic region at the am inoterminal end, are shared by most LTPs. A transcript of 630 nt was f ound in all tissues tested, except nodules. Levels of mRNA increased i n root hairs 24 hr after treatment with Rhizobium sp. NGR234, with dif ferent hormones, or with Nod factors. Amounts of transcripts were depe ndent on the concentration of Nod factors, Accumulation of transcripts during nodule development correlated with root hair deformation, the first visible step in the Rhizobirrm-legume symbiosis.