Instability at the k2 Mdh1-n y20 chromosomal region in soybean

Ten mutants have been reported at the k2 (tan saddle seed coat) Mdh1-n (mitochondrial malate dehydrogenase 1 null) y20 (yellow foliage) chromosomal region in soybean [Glycine max (L.) Merr.]. The precise genetic mechanism(s) responsible for generating these mutants is (are) not known. The objective of this study was to determine whether chromosomal instability exists at this region. We introduced the w4-m and Y18-m mutable systems into the three independent sources of tan saddle seed coat mutants, T239 (k2), T261 (k2 Mdh1-n), and L67-3483 (k2). A total of 12 bright yellow mutants were isolated with tan saddle seed coat, malate dehydrogenase 1 null phenotypes. Of these, 11 were found in 11 F2 mutant families out of a total of 977 derived by crossing T239 (k2), T261 (k2 Mdh1-n), and L67-3483 (k2) with six lines suspected to contain active transposable elements. One was found in the F3 generation derived from the cross A1937?×?T239 (k2). Of the 11 F2 mutant families, 10 (out of a total of 381 F2 families) were associated with the T239 (k2) genetic background, and one out of 323 was associated with the T261 (k2 Mdh1-n) genetic background. But no mutation events were found among the 273 families with the L67-3483 (k2) genetic background. Allelism and inheritance studies indicated that these 12 bright yellow mutants were new mutants in the k2 Mdh1-n y20 chromosomal region. Thus, on introducing the w4-m and Y18-m mutable systems into T239 (k2) and T261 (k2 Mdh1-n) genetic backgrounds, chromosomal instability was induced in this region. In addition, 21 greenish yellow mutants were identified in the total of 977 F2 families. All 21 greenish yellow mutants were associated with the T239 (k2) genetic background. The mutations for greenish yellow foliage affected foliage color only at the seedling stage. Cosegregation of the tan saddle seed coat character with greenish yellow foliage were observed for these 21 greenish yellow mutants, suggesting that the greenish yellow phenotype may be due to a pleiotropic effect of the k2 allele in T239 or to chromosomal rearrangements at or near the k2 allele in T239. Finally, we believe that the genetic mechanism responsible for this high frequency of instability at the k2 Mdh1-n y20 chromosomal region involves receptor element activities present at this chromosomal region, which may contain complex chromosomal rearrangements in T239 and T261.     

Instability at the k2 Mdh1-n y20 chromosomal region in soybean

Ten mutants have been reported at the k2 (tan saddle seed coat) Mdh1-n (mitochondrial malate dehydrogenase 1 null) y20 (yellow foliage) chromosomal region in soybean [Glycine max (L.) Merr.]. The precise genetic mechanism(s) responsible for generating these mutants is (are) not known. The objective of this study was to determine whether chromosomal instability exists at this region. We introduced the w4-m and Y18-m mutable systems into the three independent sources of tan saddle seed coat mutants, T239 (k2), T261 (k2 Mdh1-n), and L67-3483 (k2). A total of 12 bright yellow mutants were isolated with tan saddle seed coat, malate dehydrogenase 1 null phenotypes. Of these, 11 were found in 11 F2 mutant families out of a total of 977 derived by crossing T239 (k2), T261 (k2 Mdh1-n), and L67-3483 (k2) with six lines suspected to contain active transposable elements. One was found in the F3 generation derived from the cross A1937 × T239 (k2). Of the 11 F2 mutant families, 10 (out of a total of 381 F2 families) were associated with the T239 (k2) genetic background, and one out of 323 was associated with the T261 (k2 Mdh1-n) genetic background. But no mutation events were found among the 273 families with the L67-3483 (k2) genetic background. Allelism and inheritance studies indicated that these 12 bright yellow mutants were new mutants in the k2 Mdh1-n y20 chromosomal region. Thus, on introducing the w4-m and Y18-m mutable systems into T239 (k2) and T261 (k2 Mdh1-n) genetic backgrounds, chromosomal instability was induced in this region. In addition, 21 greenish yellow mutants were identified in the total of 977 F2 families. All 21 greenish yellow mutants were associated with the T239 (k2) genetic background. The mutations for greenish yellow foliage affected foliage color only at the seedling stage. Cosegregation of the tan saddle seed coat character with greenish yellow foliage were observed for these 21 greenish yellow mutants, suggesting that the greenish yellow phenotype may be due to a pleiotropic effect of the k2 allele in T239 or to chromosomal rearrangements at or near the k2 allele in T239. Finally, we believe that the genetic mechanism responsible for this high frequency of instability at the k2 Mdh1-n y20 chromosomal region involves receptor element activities present at this chromosomal region, which may contain complex chromosomal rearrangements in T239 and T261. Received: 7 January 1998 / Accepted: 7 July 1998     

Conditional lethality involving a cytoplasmic mutant and chlorophyll-deficient malate dehydrogenase mutants in soybean

Summary Conditional lethality in soybean, Glycine max (L.) Merr., occurred in F₂ plants when cytoplasmicchlorophyll mutant Genetic Type T275 was the female parent and when either nuclear mutants T253 or T323 plants were the male parents. Mutant T253 [Mdh1-n (Urbana) y20 (Urbana) k2] is missing two of three mitochondrial malate dehydrogenase isozymes [Mdh1-n (Urbana)] and has yellowish-green leaves [y20 (Urbana)] and a tan-saddle pattern seed coat (k2). Mutant T323 [Mdh1-n (Ames 2) y20 (Ames 2)] also is missing two of three mitochondrial malate dehydrogenase isozymes [Mdh1-n (Ames 2)] and has yellowishgreen leaves [y20 (Ames 2)], but has yellow seed coat (K2). Mutants T275, T253, and T323 are viable both in the field and glasshouse. The genotypes cyt-Y2 Mdh1-n (Urbana) y20 (Urbana) k2/Mdh1-n (Urbana) y20 (Urbana) k2 and cyt-Y2 Mdh1-n (Ames 2) y20 (Ames 2)/Mdh1-n (Ames 2) y20 (Ames 2) are conditional lethals. These genotypes are lethal under field conditions, but plants survive in reduced light under shadecloth in the glasshouse. We do not know if their interaction with cyt-Y2 is due to Mdh1-n, y20, or Mdh1-n y20. The reciprocal cross (cyt-Y2 as male parent) gives viable genotypes. These conditional lethal genotypes should be useful for studies on the interaction between organelle and nuclear genomes.This is journal paper no. J-14777 of the Iowa Agriculture and Home Economics Experiment Station, Ames, IA 50011-1010. Project 2985     

Genetic analyses of two independent chlorophyll-deficient mutants identified among the progeny of a single chimeric foliage soybean plant

Chimeric (variegated) foliage plants are frequently observed in many species. In soybean [Glycine max(L.) Merr.], progeny of chimeric plants are a source of nuclear and cytoplasmically inherited mutants. Self-pollinated progeny of a single chimeric plant derived from tissue culture of PI 427099 (Jilin 3) included plants with green foliage, chimeric foliage, yellow foliage (viable), and yellow foliage (lethal). Our objectives were to determine (1) inheritance, linkage, and allelism of the lethal-yellow mutant with known chlorophyll-deficient mutants; (2) inheritance, linkage, and allelism of the viable-yellow mutant with known chlorophyll-deficient mutants; (3) allelism of the lethal-yellow mutant with the viable-yellow mutant; and (4) male and female gamete transmission of the viable-yellow mutant trait. The viable-yellow mutant was allelic to T323, y20 y20 (Ames 2) Mdh1-n Mdh1-n (Ames 2) and was assigned genetic type collection number T361 and gene symbol y20 y20 (Ames 24) Mdh1-n Mdh1-n (Ames 22). The lethal-yellow mutant was allelic to T225H (Y18 y18) and was assigned genetic type collection number T362H and gene symbol Y18 y18 (Ames 2). T225H became Y18 y18 (Ames 1). The two chlorophyll-deficient mutants were not linked to each other. There was no significant difference in F(1) male or female gamete transmission of the viable-yellow mutant. However, many cross-combinations gave significant deviations from the expected 3 green plants:1 viable-yellow plant in the F(2) generation. The allelism of these two chlorophyll-deficient mutants with mutants T225H and T323, derived from putative transposable element systems, is intriguing. An explanation of this phenomenon awaits molecular experimentation.     

Molecular mapping of k2 Mdh1-n y20, an unstable chromosomal region in soybean [Glycine max (L.) Merr.]

In the soybean genome, a chromosomal region covering three tightly linked genes, k2, Mdh1-n, and y20, was found very unstable. It was suspected that the instability of the k2 Mdh1-n y20 chromosomal region was caused by a non-autonomous transposable element residing adjacent to or in this region. In this study, we located and mapped this region with simple sequence repeat (SSR) markers on the soybean integrated map using five mapping populations. The k2 Mdh1-n y20 chromosomal region was located on molecular linkage group H. The integrated map from five mapping populations consisted of 13 loci in the order Satt541, Satt469, Sat_122, Satt279, Satt253, Satt314, Mdh1-n,y20, k2, Satt302, Satt142, Satt181, and Satt434. The k2 Mdh1-n y20 chromosomal region was very close to Satt314, Satt253, and Satt279. The genetic distance between the Mdh1-n gene and Satt314 was less than 1 cM. The results of the mapping study were consistent with the results from previous studies that the Mdh1-n mutation in T261 (k2 Mdh1-n) and the Mdh1-n y20 mutation in T317 (Mdh1-n y20) were caused by deletions. In addition, another putative deletion was found in the genome of T261 which covered three SSR markers (Satt314, Satt253, and Satt279). This is a joint contribution of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa, Project No. 3769, and from the USDA, Agricultural Research Service, Corn Insects and Crop Genetics Research Unit, and supported by the Hatch Act and the State of Iowa. The mention of a trademark or proprietary product does not constitute a guarantee or warranty of the product by Iowa State University or the USDA, and the use of the name by Iowa State University or the USDA implies no approval of the product to the exclusion of others that may also be suitable.     

Nuclear-cytoplasmic interaction in chlorophyll-deficient soybean,Glycine max (Fabaceae)

In higher plants, plastids and mitochondria are the predominant carriers of extrachromosomal genetic information. There is interplay between the plastids, the mitochondria, and the nuclear genome. In soybean, Glycine max (L.) Merr., both nuclearly and maternally inherited chlorophyll-deficient mutants have been described. Conditional lethality previously was reported in soybean when maternally inherited chlorophyll-deficient mutant (Genetic Type T275) was crossed with nuclearly inherited yellow foliar malate dehydrogenase null mutants (Genetic Types T253 and T323). Our objective was to test for conditional lethality when maternally inherited yellow foliar mutants T278, T314, T315, T316, T319, and T320 were female parents and nuclearly inherited yellow foliar malate dehydrogenase null mutants T253 and T323 were male parents. Our results indicated conditional lethality in the F₂ generation when any of the six cytoplasmically inherited yellow foliar mutants were female parents and either T253 or T323 were male parents. The physiological nature of conditional lethality is not known. Data indicate a common basis in soybean for conditional lethality among the cytoplasmically inherited yellow foliar mutants when crossed with the nuclearly inherited yellow foliar malate dehydrogenase null mutants. No interactions were observed between cytoplasmically inherited or nuclearly inherited green seed embryo mutants as female parents and either T253 or T323 as male parents.     

Independent spontaneous mitochondrial malate dehydrogenase null mutants in soybean are the result of deletions

The mitochondrial malate dehydrogenase-1 (Mdh1) gene of soybean [Glycine max (L.) Merr.] spontaneously mutates to a null phenotype at a relatively high rate. To determine the molecular basis for the instability of the Mdh1 gene, the gene was cloned and sequenced. The null phenotype correlated with the deletion of specific genomic restriction fragments that encode the Mdh1 gene. The composition of the Mdh1 gene and its environs were compared with those of the more stable MDH2 gene. Several possible causes of the observed instability were found, including duplications, repeats, and two regions with similarity to a soybean catalase. The most likely cause of instability, however, appeared to be a 1233 bp region with 58.9% identity to the Cyclops retrotransposons. Translation of a 714 bp segment of this region produced a peptide composed of 238 amino acid residues that showed 35-40% identity and 55-60% similarity to several putative Cyclops gag-pol proteins (group-specific antigen polyprotein). This short peptide also contained a segment that corresponded to the protease active site of the gag-pol protein. Thus in an appropriate genetic background, a retrotransposon, whether whole or fractured, could promote genetic rearrangements.     

Inheritance of two independent isozyme variants in soybean plants derived from tissue culture

Summary Soybean [Glycine max (L.) Merr.] plants were regenerated via somatic embryogenesis from nine soybean cultivars. Our objective was to identify and characterize genetically novel mutations that would further our understanding of the soybean genome. Variant isozyme patterns were observed in two independent tissue culturederived lines. Genetic analyses were conducted on these two isozyme variants, and they were heritable. No variant isozyme patterns were evident in control (parental) soybean lines. In the cultivar BSR 101, a mutation of Aco2-b (aconitase) to a null allele was detected. The Aco2-bn mutant, Genetic Type T318, had not been previously observed in soybean. In the Chinese cultivar Jilin 3 (PI 427.099), a chlorophyll-deficient plant was identified that also lacked two mitochondrial malate-dehydrogenase (Mdh null) isozyme bands. These two mutant phenotypes, chlorophyll-deficient and Mdh null, were found to cosegregate. The Jilin 3 mutant, Mdh1-n (Ames 1) y20 (Ames 1) Genetic Type T317, was allelic to three chlorophyll-deficient, Mdh1 null mutants [Mdh1-n (Ames 2) y20 (Ames 2) (T323), Mdh1-n (Ames 3) y20 (Ames 3) (T324), and Mdh1-n (Ames 4) y20 (Ames 4) (T325)] previously identified from a transposon-containing soybean population, and to a chlorophyll-deficient, Mdh1 null mutant [Mdh1-n (Urbana) y20 (Urbana) k2, Genetic Type T253] which occurred spontaneously in soybean. The recovery of two isozyme variants from progeny of 185 soybean plants regenerated from somatic embryogenesis indicates the feasibility of selection for molecular variants.     

Inheritance of malate dehydrogenase nulls in soybean

Three chlorophyll-deficient mutants (CD-1, CD-2, and CD-3), derived from the progeny of independent germinal revertants from the w4-mutable soybean line [Glycine max (L.) Merrill], were characterized genetically. Electrophoretic analyses indicated that these lines lacked two of three mitochondrial malate dehydrogenase isozymes (MDH-). The absence of two MDH bands was conditioned by a recessive allele at a locus designated Mdh1. All three CDs were allelic to each other and to T253, a Harosoy isoline y20-k2 MDH- from the Genetic Type Collection. The MDH- phenotype and the yellow-green plant phenotype were each inherited as single recessive alleles. No recombination between the two traits was found in nine F2 populations from crosses of the CDs by wild-type soybean lines. Complete linkage of the Mdh1 and y20 loci suggested that the mutations in the chlorophyll-deficient lines were deletions. Phenotypic differences among the CDs suggested that the deletions may have different endpoints. The chromosomal aberrations were not large enough to affect transmission of y20 and Mdh1 mutant alleles through the pollen or ovule. CD-1, CD-2, and CD-3 were added to the Soybean Genetic Type Collection as T323, T324, and T325, respectively.     

Chromosomal Location of Two Mitochondrial Malate Dehydrogenase Structural Genes in ZEA MAYS Using Trisomics and B-A Translocations

Maize mitochondrial malate dehydrogenase is coded by four genetic loci, Mdh1, Mdh2, Mdh3 and Mdh4. Two of the four loci have been located on the long arm of chromosome 6, using trisomic analysis and B-A translocations.     

Genetic control of malate dehydrogenase isozymes in maize

At least six nuclear loci are responsible for the genetic control of malate dehydrogenase (L-malate: NAD oxidoreductase; EC 1.1.1.37; MDH) in coleoptiles of maize. Three independently segregating loci (Mdh1, Mdh2, Mdh3) govern the production of MDH isozymes resistant to inactivation by ascorbic acid and found largely or solely in the mitochondria. A rare recessive allele found at a fourth nuclear locus (mmm) causes increased electrophoretic mobility of the MDH isozymes governed by the Mdh1, Mdh2 and Mdh3 loci.—Two loci (Mdh4, Mdh5) govern MDH isozymes that are selectively inactivated by homogenization in an ascorbic acid solution and that appear to be nonmitochondrial (soluble). Mdh4 and Mdh5 segregate independently of each other and independently of Mdh1, Mdh2 and Mdh3. However, there is close linkage between the migration modifier and Mdh4.——Multiple alleles have been found for all of the Mdh loci except the migration modifier, and electrophoretically "null" or near "null" alleles (as expressed in standardized sections of maize coleoptile) have been found for all loci except Mdh4. Duplicate inheritance commonly occurs for Mdh1 and Mdh2 and also for Mdh4 and Mdh5.——Inter- and intragenic heterodimers are formed between sub-units specified by the three loci governing the mitochondrial MDH isozymes. The same is true of the alleles and nonalleles at the two loci governing the soluble variants. No such heterodimers are formed by interactions between mitochondrial and soluble MDH isozymes.     

褐色种皮大豆与其黄色种皮衍生亲本的表型及基因型比较

大豆种皮色在从野生大豆到栽培大豆的选择过程中逐渐由黑色变成黄色,是重要的形态标记,因此,大豆种皮色相关基因的研究无论是对进化理论研究还是育种实践都具有非常重要的意义。利用褐色种皮J1265-2大豆及其衍生亲本黄色种皮大豆J1265-1为材料,通过SSR引物扩增片段,检验遗传背景的异同,同时对控制种皮的候选基因GmF3’H进行扩增和测序分析。结果表明,褐色种皮和黄色种皮材料不仅用161对SSR分子标记检测没有发现差异,其褐色种皮候选基因GmF3’H的编码区及起始密码子上游1465 bp序列也是一致的。因此,证明褐色种皮J1265-2大豆与其衍生亲本黄色种皮大豆J1265-1为近等基因系,其控制褐色种皮的基因型与已报道的基因型不同。     

Isozyme analysis in a genetic collection of amaranths (Amaranthus L)

In various populations of the cultivated and weedy amaranth species, the electrophoretic patterns of alcohol dehydrogenase (ADH), glutamate dehydrogenase (GDH), malate dehydrogenase (MDH), isocitrate dehydrogenase (IDH) and malic enzyme (Me) were studied. In total, 52 populations and two varieties (Cherginskii and Valentina) have been examined. Allozyme variation of this material was low. Irrespective of species affiliation, 26 populations and two varieties were monomorphic for five enzymes; a slight polymorphism of three, two, and one enzymes was revealed in three, nine, and fourteen populations, respectively. A single amaranth locus, Adh, with two alleles, Adh F and Adh S, controls amaranth ADH. Two alleles, common Gdh S and rare Gdh F, control GDH; no heterozygotes at this locus were found. The MDH pattern has two, the fast- and slow-migrating, zones of activity (I and II, respectively). Under the given electrophoresis conditions, the fast zone is diffuse, whereas slow zone is controlled by two nonallelic genes, monomorphic Mdh 1 and polymorphic Mdh 2 that includes three alleles: Mdh 2-F, Mdh 2-N, and Mdh 2-S. Low polymorphism of IDH and Me was also found, though their genetic control remains unknown.     

Inheritance of seed coat color genes in <Emphasis Type="Italic">Brassica napus</Emphasis> (L.) and tagging the genes using SRAP,SCAR and SNP molecular markers

Seed coat color inheritance in Brassica napus was studied in F₁, F₂, F₃ and backcross progenies from crosses of five black seeded varieties/lines to three pure breeding yellow seeded lines. Maternal inheritance was observed for seed coat color in B. napus, but a pollen effect was also found when yellow seeded lines were used as the female parent. Seed coat color segregated from black to dark brown, light brown, dark yellow, light yellow, and yellow. Seed coat color was found to be controlled by three genes, the first two genes were responsible for black/brown seed coat color and the third gene was responsible for dark/light yellow seed coat color in B. napus. All three seed coat color alleles were dominant over yellow color alleles at all three loci. Sequence related amplified polymorphism (SRAP) was used for the development of molecular markers co-segregating with the seed coat color genes. A SRAP marker (SA12BG18388) tightly linked to one of the black/brown seed coat color genes was identified in the F₂ and backcross populations. This marker was found to be anchored on linkage group A9/N9 of the A-genome of B. napus. This SRAP marker was converted into sequence-characterized amplification region (SCAR) markers using chromosome-walking technology. A second SRAP marker (SA7BG29245), very close to another black/brown seed coat color gene, was identified from a high density genetic map developed in our laboratory using primer walking from an anchoring marker. The marker was located on linkage group C3/N13 of the C-genome of B. napus. This marker also co-segregated with the black/brown seed coat color gene in B. rapa. Based on the sequence information of the flanking sequences, 24 single nucleotide polymorphisms (SNPs) were identified between the yellow seeded and black/brown seeded lines. SNP detection and genotyping clearly differentiated the black/brown seeded plants from dark/light/yellow-seeded plants and also differentiated between homozygous (Y2Y2) and heterozygous (Y2y2) black/brown seeded plants. A total of 768 SRAP primer pair combinations were screened in dark/light yellow seed coat color plants and a close marker (DC1GA27197) linked to the dark/light yellow seed coat color gene was developed. These three markers linked to the three different yellow seed coat color genes in B. napus can be used to screen for yellow seeded lines in canola/rapeseed breeding programs.     

Isozyme Analysis in a Genetic Collection of Amaranths (<Emphasis Type="Italic">Amaranthus</Emphasis> L.)

In various populations of the cultivated and weedy amaranth species, the electrophoretic patterns of alcohol dehydrogenase (ADH), glutamate dehydrogenase (GDH), malate dehydrogenase (MDH), isocitrate dehydrogenase (IDH) and malic enzyme (Me) were studied. In total, 52 populations and two varieties (Cherginskii and Valentina) have been examined. Allozyme variation of this material was low. Irrespective of species affiliation, 26 populations and two varieties were monomorphic for five enzymes; a slight polymorphism of three, two, and one enzymes was revealed in three, nine, and fourteen populations, respectively. A single amaranth locus, Adh, with two alleles, Adh F and Adh S, controls amaranth ADH. Two alleles, common Gdh S and rare Gdh F, control GDH; no heterozygotes at this locus were found. The MDH pattern has two, the fast- and slow-migrating, zones of activity (I and II, respectively). Under the given electrophoresis conditions, the fast zone is diffuse, whereas slow zone is controlled by two nonallelic genes, monomorphic Mdh 1 and polymorphic Mdh 2 that includes three alleles: Mdh 2-F, Mdh 2-N, and Mdh 2-S. Low polymorphism of IDH and Me was also found, though their genetic control remains unknown.     

Circling,deafness, and yellow coat displayed by yellow submarine (ysb) and light coat and circling (lcc) mice with mutations on chromosome 3

We describe here two mouse mutants, yellow submarine (Ysb) and light coat and circling (Lcc). Ysb arose as the result of insertions of a transgene, pAA2, into the genome. Lcc is an independent, radiation-induced mutation. Both mutants are characterized by recessive circling behavior and deafness, associated with a non-segregating, semi-dominant yellow coat color. Complementation tests showed that Ysb and Lcc are allelic. We attribute the yellow coat in Ysb and Lcc mice to the absence of black awl overhairs, increased agouti zigzag underhairs, and the presence of agouti awls with long subapical yellow pigment. Chromosomal mapping and genomic characterization showed the Ysb and Lcc mutations involve complex chromosomal rearrangements in overlapping regions of mouse chromosome 3, A2/A3-B/C and B-E1, respectively. Ysb and Lcc show for the first time, to our knowledge, the presence of genes in the B-C region of chromosome 3 important for balance and hearing and the pigmentation and specification of coat hair.     

Monomorphism of isozyme loci in natural and cultivated amaranth (<Emphasis Type="Italic">Amaranthus</Emphasis> L.) populations

Electrophoretic spectra of alcohol dehydrogenase (ADH), glutamate dehydrogenase (GDH), malate dehydrogenase (MDH), isocitrate dehydrogenase (IDH), and malic enzyme (ME) in different amaranth populations has been studied using a starch gel electrophoresis. 93 populations and 4 cultivars of amaranth have been analyzed. Some populations have been proved to be polymorphic that provided a possibility of a genetic control of the above-mentioned enzymes. The isozyme variability of the studied amaranth populations is low; all studied loci are found to be monomorphic for 73 populations and 4 cultivars. Some populations demonstrate a polymorphism in separate loci (Adh, Mdh 2, Gdh, Idh 1, Idh 2, and Mod 2). The obtained results evidence the presence of a genetic monomorphism in amaranth concerning the loci studied.     

Malate Dehydrogenase, Alcohol Dehydrogenase, and 6-Phosphogluconate Dehydrogenase Isozymes of Zea mays L. × Tripsacum dactyloides L. Hybrids and Parents

Electrophoretic patterns of malate dehydrogenase (Mdh), alcohol dehydrogenase (Adh), and 6-phosphogluconate dehydrogenase (Pgd) of Zea mays L. × Tripsacum dactyloides L. hybrids and their parents were compared. The components of enzymes specific to T. dactyloides may be used as markers to identify the following T. dactyloides chromosomes in the hybrids: Tr 16 (Mdh 2 and Pdg 1), Tr 7, and/or Tr 13 (Adh 2). The isozymes of Mdh 2 are supposed as a possible biochemical marker to evaluate the introgression of genes, determining an apomictic mode of reproduction from T. dactyloides (localized on Tripsacum 16 chromosome) into Z. mays. The isozymes may be used as markers for the identification of maize chromosomes 1 and 6 in the hybrids as well. Chromosome count taken on the examined hybrids showed the addition of 9 to 13 chromosomes of T. dactyloides to maize chromosome complement.     

Subcellular localization of isozymes of NAD-dependent malate dehydrogenase in sugar beet <Emphasis Type="Italic">Beta vulgaris</Emphasis> L.

Subcellular localization of isozymes of NAD-dependent malate dehydrogenase (MDH) in sugar beet was studied. Isozymes ss and ll controlled by loci Mdh2 and Mdh3, respectively, were shown to locate in mitochondria, whereas isozyme pp controlled by locus Mdh1, in microbodies. All examined samples lack hybrid MDH isozymes, which could testify to the interaction between products of nonallelic Mdh genes. This can be explained by the localization of nonallelic isozymes in various compartments of the cell and organelles.