Nuclear and mitochondrial DNA have sequence homology with a chloroplast geneWhisson, Dara; Steele Scott, N.
doi: 10.1007/BF02418245pmid: 24310876
A PstI 7.7 kbp fragment from chloroplast (ct) DNA of spinach shows homology to an EcoRI 8.3 kbp fragment of mitochondrial (mt) DNA and in turn, both are homologous to a number of common regions of nuclear (n) DNA. The common area of homology between the chloroplast and mitochondrial fragments is between a KpnI 1.8 segment internal to the PstI sites in the ctDNA and an EcoRI/BamHI 2.9 kbp fragment at one end of the mitochondrial 8.3 kbp fragment. The KpnI 1.8 kbp ctDNA fragment is within a structural gene for the P700 chlorophyll a apoprotein. Further analysis of this KpnI 1.8 kbp fragment confined the homologous region in mtDNA to a ct 0.8 kbp HpaII fragment. These smaller pieces of the organellar genomes share homologies with nuclear DNA as well as displaying unique hybridization sites. The observations reported here demonstrate that there is a common or closely related sequence in all three genetic compartments of the cell.
Patterns of post-infectional protein synthesis in barley carrying different genes for resistance to the powdery mildew fungusManners, J.; Davidson, A.; Scott, K.
doi: 10.1007/BF02418246pmid: 24310877
Pairs of susceptible and resistant, near-isogenic cultivars ofHordeum vulgare which differ for the Mla, Mlk and Mlp genes for resistance toErysiphe graminis f. sp.hordei were inoculated with race 3 of this pathogen and patterns of protein synthesis associated with primary infection mapped using pulse-labelling with L-[35S]methionine and 2-dimensional electrophoresis. Extraction of proteins with buffer containing detergent revealed the enhanced synthesis of 5 and 8 polypeptides at 25 and 30 h respectively after inoculation of barley carrying the Mla gene (cvMla). The enhanced synthesis of these same polypeptides together with 11 additional polypeptides was observed at 48 h and 72 h after inoculation of barley carrying either the Mlp (cvMlp) or Mlk (cvMlk) genes. The labelling of several major constitutive polypeptides was suppressed in cvMla at 24 h after inoculation; the labelling of six of these polypeptides was also suppressed in both cvMlp and cvMlk but not until 48 and 72 h after inoculation. These results indicate that changes occur in the synthesis of some common polypeptides following infection of cultivars carrying different resistance genes but the timing and extent of these changes varies with the resistance gene in the host.
The detection of leghemoglobin-line sequences in legumes and non-legumesHattori, J.; Johnson, D.
doi: 10.1007/BF02418247pmid: 24310878
Leghemoglobin is a major component of the nitrogen-fixing nodules formed by legumes in association with bacterial symbionts of the genusRhizobium. It is thought to be involved in regulating the oxygen tension within nodules. In a series of Southern blot experiments using cloned soybean leghemoglobin cDNAs as hybridization probes, cross-hybridizing sequences have been detected in legumes closely related to soybean (members of the Leguminosae subfamily Papilionoideae), as well as in a distantly related legume not reported to be nodulated (subfamily Caesalpinioideae). With the same probes, the presence of cross-hybridizing sequences has also been detected in plants outside the Leguminosae, including two nitrogen-fixing non-legumes and one species which is not nodulated. These results suggest that the genes for oxygen-binding proteins may be more widely dispersed than previously thought.
Localization and nucleotide sequences of the tRNA GCC Gly , tRNA GUC Asp and tRNA GCA Cys genes from wheat chloroplastQuigley, F.; Grienenberger, J.; Weil, J.
doi: 10.1007/BF02418249pmid: 24310880
The location on the wheat chloroplast DNA map and the nucleotide sequences of the genes coding for tRNA
GCC
Gly
(trnG-GCC), tRNA
GUC
Asp
(trnD-GUC) and tRNA
GCA
Cys
(trnC-GCA) have been determined. These three genes are located in the large single copy region of the chloroplast genome, about half-way between one of the inverted repeats and the gene for the α subunit of ATP synthase. They are located on two Bam H1 fragments, called B6 and B18 by Bowmanet al. (1), which are separated by about 450 bp and which were cloned in our laboratory to allow sequencing. ThetrnD-GUC andtrnC-GCA sequences show 98.6 and 89% homology, respectively, with the corresponding spinach chloroplast tRNA genes sequences (2), which are the only other higher plant chloroplasttrnD-GUC andtrnC-GCA sequenced so far, while no othertrnG-GCC sequence has been published. ThetrnG-GCC sequence shows only 58% homology with the corresponding gene sequence inEuglena chloroplasts (3).
Plant-virus-based vectors for gene transfer may be of considerable use despite a presumed high error frequency during RNA synthesisSiegel, Albert
doi: 10.1007/BF02418254pmid: 24310885
The RNA genomes of some plant viruses have properties which make them suitable for development into vectors for gene transfer. It has been claimed that the low fidelity of RNA synthesizing enzymes may limit the usefulness of such vectors. Arguments are presented here to indicate that the problem may not be serious. Examples are presented of plant RNA replicons which carry relatively stable coding sequences whose products are superfluous to either the replicon or the host. In addition, there are numerous instances in which slowly replicating virus strains are maintained in ‘pure’ culture in a host and are not overgrown by more rapidly replicating strains. It is difficult to estimate the error frequency of RNA replicating enzymes. Methods which rely on host-shift may be subject to error.