Size, location and polarity of T-DNA-encoded transcripts in nopaline crown gall tumors; common transcripts in octopine and nopaline tumors.

Up to thirteen T-DNA-encoded, polyadenylated transcripts of different relative abundance were detected by Northern blot hybridization in the tobacco nopaline BT37 crown gall teratoma tissue. Their sizes range from 900 to 2,700 bases. The polarity of eight of the thirteen transcripts was assigned by hybridization of labeled RNA to single-stranded DNA fragments of the T-region obtained by cloning in an M13 vector. Both strands of the T-DNA are transcribed. Our data indicate that most, if not all, transcripts are generated via independent promoter and poly(A)-addition sites on the T-DNA. Comparison of T-DNA-encoded transcripts present in crown gall tumors showing teratoma-like growth (BT37) with those from an unorganized tumor line (W38C58) reveals that this difference in phenotype is accompanied by a difference in the expression of the T-DNA. T-DNA sequences common to both octopine and nopaline tumors encode at least five, and probably six, cross-hybridizing transcripts of the same size, location, polarity and function. These transcripts are involved in the process of plant tumor formation and maintenance.