Genic analysis for peroxidase isozymes and their organ specificity in Oryza perennis and O. sativa

Chromosomal locations of ten isozyme loci in rice (Oryza sativa L.) through trisomic analysis

Chromosomal locations of 10 isozyme loci in rice (Oryza sativa L.) were determined through trisomic analysis. All 10 genes produced altered allozyme banding patterns in specific F1 trisomics. This served as the primary source of evidence for chromosome locations of Est-5, Icd-1, Acp-1, and Pgd-1. The locations of Amp-1, Amp-2, Amp-4, Pox-5, Got-1, and Cat-1 were further confirmed from segregation data in BC1 generations, as the ratios deviated significantly from 1:1 in the critical trisomics but agreed with the expected trisomic ratios. Triallelic heterozygotes were recovered for Amp-1 and Amp-2. On the basis of these data Got-1, Est-5, and Icd-1 were located to chromosome 1, Amp-1 to chromosome 2, Cat-1 and Pox-5 to chromosome 3, Acp-1 to chromosome 6, Amp-2 and Amp-4 to chromosome 8, and Pgd-1 to chromosome 11. Because Acp-2 and Pox-2 are known to be linked with Acp-1, they must also be on chromosome 6. The gene order and recombination values between isozyme loci on chromosomes 3, 6, 8, and 11 are presented.

The inheritance of seed peroxidases of wheat and rye: further data

Further data on the inheritance of seed peroxidases of hexaploid wheat (Triticum aestivum L.) and rye (Secale cereale L.) have been obtained from the genetic analysis of several progenies of both species. Additional data on the inheritance and the chromosomal location and linkage have been obtained for peroxidases of wheat embryo and rye endosperm. The general presence of null alleles in peroxidase loci has been confirmed in both species. In addition to simple monogenic inheritance, epistatic segregations have been observed in both species. These epistatic segregations again suggest the presence of "regulatory" genes controlling the expression of individual peroxidases in both species and also the existence of several duplicate homoeologous genes in wheat. Known linkage relationships have been confirmed and new ones are indicated. Loci for embryo wheat peroxidases seem to be in chromosomes of the homoeology group 3. The rye endosperm ones should be in chromosome 7R, although it is hypothesized that a duplication of gene EPer1 is located in chromosomes 4R and 7R.

Isozymes and classification of Asian rice varieties

Enzyme variation detected by starch gel electrophoresis was used to investigate the genetic structure of Oryza sativa L. species. Fifteen polymorphic loci coding for 8 enzymes were surveyed among 1688 traditional rices from Asia. Multivariate analysis of the data resulted in identification of six varietal groups, with two major ones, groups I and VI, two minor ones, groups II and V, and two satellite ones, groups III and IV. Group I is found throughout tropical Asia; it encompasses most Aman rices in Bangladesh, the Tjereh rices in Indonesia and the Hsien rices in China. Group VI is found mostly in temperate regions and in high elevation areas in the tropics; it encompasses most upland rices from Southeast Asia, the Bulu rices from Indonesia and the Keng rices from China. Groups II, III, IV and V share common differences from groups I and VI which suggest an alternative evolutionary history. Groups II and V are found in the Indian subcontinent from Iran to Burma. Well-known components of these are Aus rices from Bangladesh for group II and Basmati rices from Pakistan and India for group V. Groups III and IV are restricted to some deepwater rices in Bangladesh and Northeast India. Based on analogy with other classifications, Group I might be considered as the "Indica" type and Group VI as the "Japonica" type. Such terms, however, have a depreciated meaning due to discrepancies among various classifications.

The inheritance of tetraploid wheat seed peroxidases

Embryo and endosperm peroxidases from dry mature seeds of three subspecies of tetraploid wheat (Triticum turgidum L.) were subjected to genetic analysis. The inheritance of eight isozymes (embryo isozymes a2, d1, d2, e and f; and endosperm isozymes b, d and 4) were studied in F2's obtained from different wheat accessions. Simple monogenic inheritance producing three banded: one null segregation and two epistatic segregations (9∶7 and 15∶1) were found. In the case of isozymes b, d and 4, monogenic or epistatic segregation depended on the F2 analyzed. Segregation data indicated that at least 9 different loci would determine the peroxidase isozymes of tetraploid wheat seed, all the loci studied containing 'null' alleles. Furthermore, several loci determining embryo peroxidases were noticed to be mutually linked. All these data are discussed in context of the inheritance of seed peroxidases in hexaploid wheat and rye.

The inheritance of rye seed peroxidases

Genetic analyses were conducted on peroxidase of the embryo and endosperm of seeds of one open pollinated and six inbred lines of cultivated rye (Secale cereale L.), and one line of Secale vavilovii Grossh. The analyses of the individual parts of the S. cereale seed yield a total of 14 peroxidase isozymes. Isozymes m, a, b, c, d, e, f and g (in order from faster to slower migration) were found in the embryo plus scutellum, while isozymes 1, 2, 3, 4, 5 and 6 (also from faster to slower migration) were peculiar of the endosperm. S. vavilovii has isozymes m, c1, d, e, f and g in its embryo plus scutellum, and isozyme 2 in the endosperm. Segregation data indicated that at least 13 different loci would be controlling the peroxidase of S. cereale. Isozymes a and b are controlled by alleles of the same locus, all the other loci have one active and dominant allele coding for one isozyme, and other null and recessive allele. The estimation of linkage relationships shows that five endosperm loci are linked, and tentative maps are shown. A possible dosage effect and the existence of controlling gene(s) for endosperm isozyme 4 is reported. All these data and the high frequency of null alleles found are discussed in relation to recent reports.

Genetics of the peroxidase isoenzymes in Petunia : Part 3: Location and developmental expression of the structural gene prxA

As detected by starch gel electrophoresis, the fast moving anodal group of peroxidase isoenzymes, the PRXa complex, of a Petunia homozygous for the encoding gene can be made up of one to four bands, depending on the tissue sampled, the age of the tissue and of the plant, and the genetic background. Additional evidence is presented showing that the PRXa complex is encoded by one structural gene, prxA, rather than by tandem duplicated genes. On the basis of electrophoretic variation in Petunia hybrida and related species, five prxA alleles were found. A prxA internal site mutation was found recognized by the absence of recombination between the mutation that affected the temporal programme of the gene and the mutation that altered the mobility of the enzyme. By a three-point test, the gene prxA was located on chromosome III and found to be linked to the genes Mf1 and Ht1 in the order prxA-Mf1-Ht1. The construction of a trisomic III triply heterozygous for prxA confirmed the location of prxA.

Genetics of the peroxidase isoenzymes in Petunia : Part 4. Location and developmental expression of the structural gene prxcC

By starch gel electrophoresis three mobility variants of a cathodic moving doublet of bands, encoded by the structural gene prxC, were detected in all organs of flowering petunias. In root tissue two of the variants showed a lower electrophoretic mobility than in other organs. During development of flower buds the PRXc enzymes showed an increase in mobility. The gene prxC was located on chromosome IV by showing linkage to the genes An3 and Dw1, by trisomic segregation, and by the construction of triply heterozygous trisomics IV. The gene order on chromosome IV is B1-An3/Dw1-prxC. It was concluded that the temporal programming difference in the expression of the alleles prxC2 and prxC3 is caused by internal site mutation. Analysis of progeny obtained by crossing of lines to the trisomic IV with genotype prxC1/C1/C2 showed differential expression of the two prxC1 alleles of the trisomic IV.

Peroxidase and leucine-aminopeptidase in diploidMedicago species closely related to alfalfa: Multiple gene loci, multiple allelism, and linkage

The genetics of peroxidase and leucine-aminopeptidase isozymes was studied utilizing starch gel electrophoresis in the diploidsMedicago sativa L. (M. coerulea Less.) andM. falcata L. Three anodal and one cathodal sets of peroxidase isozymes identify four linked loci. In addition, two anodal sets of leucine-aminopeptidase isozymes identify two loci that may be linked. The allozymes at each of the loci segregated as expected for monomeric enzymes. However in several crosses there were deficiencies in the number of progeny in particular genotypic classes. This could result from the segregation of recessive deleterious genes linked to some of the allozyme alleles. This is the first report of multiple loci and multiple alleles determining isozymes inMedicago.

Isozymes, plant population genetic structure and genetic conservation

The exploration, conservation and use of the genetic resources of plants is a contemporary issue which requires a multidisciplinary approach. Here the role of population genetic data, particularly those derived from electrophoretic analysis of protein variation, is reviewed. Measures of the geographic structure of genetic variation are used to check on sampling theory. Current estimates justify the contention that alleles which have a highly localised distribution, yet are in high frequency in some neighbourhoods, represent a substantial fraction of the variation. This class, which is the most important class in the framing of sampling strategies, accounts for about 20-30% of variants found in 12 plant species. The importance of documenting possible coadapted complexes and gene-environment relationships is discussed. Furthermore, the genetic structure of natural populations of crop relatives might suggest the best structure to use in the breeding of crops for reduced vulnerability to pest and disease attack, or for adaptation to inferior environments. The studies reported to date show that whilst monomorphic natural populations do occur, particularly in inbreeding colonisers, or at the extreme margins of the distribution, polymorphism seems to be the more common mode. It is stressed here that the genetic resources of the wild relatives of crop plants should be systematically evaluated. These sources will supplement, and might even rival, the primitive land races in their effectiveness in breeding programmes. We may look forward to a wider application of gel electrophoresis in the evaluation of plant genetic resources because this technique is currently the best available for detecting genetic differences close to the DNA level on samples of reasonable size.

Esterase and acid phosphatase polymorphism in the fig tree (Ficus carica L.)

The genetics of two enzymatic loci, esterase (Est-D) and acid phosphatase (AcP-A), were studied by means of polyacrylamide gel electrophoresis in the fig tree (Ficus carica L.). Two codominant alleles are described at the Est-D locus and four codominant alleles at the AcP-A locus. Heterozygotes at the AcP-A locus have a hybrid band, thus showing that the AcP-A allozymes, are at least dimer molecules. Both loci are independent of the male sterility factor in F. carica. The polymorphism in four natural populations was investigated for both loci. A significant deficiency of heterozygotes was observed.

GENIC ANALYSIS FOR ACID PHOSPHATASE ISOZYMES IN ORYZA PERENNIS AND O. SATIVA

It was concluded from genetic experiments that various acid phosphatase zymograms observed among the rice strains belonging to Oryza perennis Moench (wild) and O. sativa L. (cultivated) were controlled by alleles at three loci, Acp1, Acp2, and Acp3. At Acp1 seven codominant alleles were found each producing a group of three major (A, M, and C) and three minor (a, m, and c) bands on starch gel. The alleles determined mobility of the band group. Statistical analysis of the data taken from densitometric tracings of zymograms indicated that hybrids between strains with different mobilities would produce three major and three minor hybrid bands each occurring between two corresponding parental bands. In addition, a null form lacking all these bands was found that had a recessive allele, Acp1Nu1. The Acp1 locus was independent of Px1 (specifying peroxidase OC, 2A, and 4A bands), but was linked withPx2 (specifying peroxidase 4C band). The Acp2 locus carried two codominant alleles specifying bands Fa and Sa, respectively, and a recessive silent allele, Acp2Nu1. This locus was closely linked with Acp1, yet it was distinguished from the latter as different allelic combinations were observed among parental strains. At Acp3 alleles specifying bands B and b were found which were peculiar to O. perennis subsp. barthii; other perennis and sativa strains appeared to have their recessive silent alleles.