Three polymorphisms in the 3' UTR of the TRAIL (TNF-related apoptosis-inducing ligand) gene.

Screening of the TRAIL (TNF-related apoptosis inducing ligand/Apo-2L) gene revealed three single nucleotide polymorphisms (SNPs) in the 3' UTR at nucleotides 1525G/A, 1588G/A, and 1591C/T. Over 50 individuals from each of two populations, Caucasian and African Americans, were genotyped for these three polymorphisms and allele frequencies were determined.

High transmission of paternal plastid DNA in alfalfa plants demonstrated by restriction fragment polymorphic analysis.

A high frequency of paternal plastid transmission occurred in progeny from crosses among normal green alfalfa plants. Plastid transmission was analyzed by hybridization of radiolabeled alfalfa plastid DNA (cpDNA) probes to Southern blots of restriction digests of the progeny DNA. Each probe revealed a specific polymorphism differentiating the parental plastid genomes. Of 212 progeny, 34 were heteroplastidic, with their cpDNAs ranging from predominantly paternal to predominantly maternal. Regrowth of shoots from heteroplasmic plants following removal of top growth revealed the persistence of mixed plastids in a given plant. However, different shoots within a green heteroplasmic plant exhibited paternal, maternal, or mixed cpDNAs. Evidence of maternal nuclear genomic influence on the frequency of paternal plastid transmission was observed in some reciprocal crosses. A few tetraploid F1 progeny were obtained from tetraploid (2n=4x=32) Medicago sativa ssp. sativa x diploid (2n=2x=16) M. sativa ssp. falcata crosses, and resulted from unreduced gametes. Here more than the maternal genome alone apparently functioned in controlling plastid transmission. Considering all crosses, only 5 of 212 progeny cpDNAs lacked evidence of a definitive paternal plastid fragment.

Direct embryogenesis from single mesophyll protoplasts in alfalfa (Medicago sativa L.).

We used a tetraploid clone derived from an anther culture operation of 'Ladak' alfalfa to study the pathway of direct embryogenesis from leaf-mesophyll protoplasts. About 72% of the protoplasts divided, and 7% of those produced proembryos. Approximately 38% of the proembryos developed into green embryos, and 33% initiated calluses. Other proembryos dedifferentiated into calluses which later redifferentiated embryos. Sixteen percent of the embryos developed directly into plants, whereas 81% produced plants indirectly via secondary embryos. The remaining 3% of the primary embryos failed to develop into plants. The lowest plating efficiency for direct embryogenesis was 0.3%. The high percentage of direct embryogenesis observed was related to the genetic nature of the clone, low density of liquid medium, low protoplast culture density, and the composition of culture media.

Restriction endonuclease analysis of mitochondrial DNA from sorghum with fertile and male-sterile cytoplasms.

Mitochondrial DNA from four paired (fertile and male-sterile) lines and six isocytoplasmic strains of sorghum (Sorghum bicolor (L.) Moench) were fragmented by endonucleases and their electrophoretic patterns were examined. Cytoplasmic male sterile lines differed from their male-fertile counterparts consistently. Among the isocytoplasmic strains, KS 36A (S. verticilli-florum cytoplasm), KS 38A (S. conspicum cytoplasm), and KS 39A (S. niloticum cytoplasm) showed minor differences from the other strains. Results suggest that restriction endonuclease patterns are useful in detecting differences in mitochondrial genomes.

In vitro culture of pods from annual and perennial Medicago species.

Because most interspecific Medicago embryos abort before they can be excised and cultured, our objective was to grow young pods in vitro. Various media were used to grow three-day-old pods of annuals [diploids, M. blancheana Boiss., M. disciformis DC., tetraploid M. scutellata (L.) Mill.] and perennials (diploid M. falcata L., tetraploid M. sativa L.).Few pods of perennial species grew to maturity on media containing modified Hoagland's plus 1% glucose or sucrose with or without 5% potato extract. Increasing sucrose to 6% increased the percentage of M. sativa pods that produced mature seeds. On DM (differentiation medium), the best medium, the percentage of pods producing viable seeds was: M. blancheana (82), M. disciformis (81), M. scutellata (48), M. sativa (63), M. falcata (15). DM plus 1 ppm indoleacetic or gibberellic acid did not enhance seed production.