Male recombination in Brazilian populations of Drosophila ananassae

With few exceptions, spontaneous crossing over does not normally occur in male Drosophila. Drosophila ananassae males show considerable amounts of crossing over. In wild males of D. ananassae from Asian (2008) and Brazilian populations (1986 and 2007) variable frequencies of meiotic crossing over, estimated from chiasmata counts, suggested the existence of factors controlling male crossing over in these populations. To corroborate for such prediction, we present data on spontaneous recombination in F1 males of D. ananassae heterozygous for chromosomes of the same Brazilian populations (1986) and marker chromosomes using three testers stocks. Mean recombination value was low, although high variability existed between individual frequencies. Recombination frequencies between lines in each tester stock were not significantly different, excepting when the 3ple-px and 3ple-cy testers were compared (p < 0.05). These two testers differ in respect to the regional distribution of crossovers. The occurrence of recombination in chromosomes 2 and 3 in F1 males tested with e65 se; bri ru was not related, suggesting they are under independent genetic control. Our data are consistent with proposed genetic factors controlling male crossing over in the tester stocks and to the presence of enhancers and suppressors of male crossing over segregating in the Brazilian populations (1986).

Molecular Genetics of Rust Resistance in Poplars (Melampsora larici-populina Kleb/Populus sp.) by Bulked Segregant Analysis in a 2 × 2 Factorial Mating Design

With random amplified polymorphic DNA (RAPD) markers, we have tagged a genomic region in Populus sp. involved in qualitative resistance to Melumpsora larici-populina. Our approach was based on three steps: use of RAPD markers that can be quickly and efficiently researched; application of “bulked segregant analysis” technique on individuals of one interspecific family P. trichocarpa × P. deltoides to search for RAPD markers linked to resistance; and validation of these markers in two other families linked with the first one in a 2 × 2 factorial mating design. Of five detected markers, only one marker M03/04_480 was polymorphic in the three segregating families, involving 89 individuals and four different parents. We have estimated the recombination value of 1 cM with 1 cM sampling error.

Linkage analysis of the gene encoding precursor protein of diapause hormone and pheromone biosynthesis-activating neuropeptide in the silkmoth, Bombyx mori

SummaryWe have determined the map position of the gene encoding a common precursor protein for diapause hormone and pheromone biosynthesis-activating neuropeptide (the DH-PBAN gene, Dh)in the silkmoth, Bombyx mori. First we compared the structure of introns in the DH-PBAN gene by the polymerase chain reaction, and found that the Dh locus carried three alleles, DhA1, DhA2 and DhB. The DhA1 and DhA2 alleles contained a fourth intron consisting of 740 bp, whereas DhB had a longer fourth intron of 770 bp. DhA1 and DhA2 contained a fifth intron consisting of 940 bp, whereas the fifth intron in DhB was much longer and consisted of 1700 bp. DhA1 was distinguished from DhA2 by an RFLP in the fifth intron after digestion with Rsa I. Linkage analyses using these polymorphisms showed that Dh was linked to the bp gene on chromosome 11, and independent of markers on chromosomes 1, 2, 3, 4, 5, 6, 7 and 13. To determine the map position, we obtained F1 hybrids between the n501 strain (K DhA1) and the w30 strain ( + KDhB), and backcrossed the F1 hybrid to females of the w30 strain. From the segregation of K and Dh in 864 individuals in the next generation, the recombination value was calculated as 25·5 % between K and Dh. Similarly we obtained backcross progeny between the No. 744 strain (BuDhA1) and the w30 strain ( + BuDhB), and calculated the recombination value between Bu and Dh as 30·4% from 487 progeny. Because k and Bu had already been mapped at positions 11–23·2 cM and 11–28·7 cM, respectively, we mapped Dh at 11--2·2 cM. The Dh locus is different from any loci which are known to control diapause, development or growth.

Inheritance and linkage relationships of genes conditioning hullessness, multiflorous spikelet, and giantism in oat (Avena sativa L.)

A study was conducted to determine the number of genes, type of gene action, and linkage relationships of the factors controlling the expression of hullessness, multiflorous spikelet and giantism in oat (Avena sativa L. var. PI 546363). The results showed that giantism was governed by a recessive gene, which in a homozygous (gi-3/gi-3) condition may have an epistatic effect on several other loci including those controlling the expression of plant height; length, width, and thickness of leaves; culm diameter; number of internodes; panicle size; pedicle length; and number of days to anthesis and to maturity. The results also indicated monogenic inheritance for hull and spikelet characteristics. Hullessness (N-1/_) was dominant over hulledness (n-1/n-1), and multiflorous spikelet (Mf-1/-) was partially dominant over normal spikelet (mf-1/mf-1). Linkage was detected between the gi-3 locus controlling giantism, and the n-1 locus controlling hullessness; the recombination value was calculated to be 36.5 ± 0.8%. Linkage was also detected between the gi-3 gene and the Mf-1 locus conditioning multiflorous spikelet; the recombination value was 23.5 ± 0.4%. The N-1 gene appears to have an epistatic effect on the Mf-1 locus, and the recombination frequency between the two loci was 10.5 ± 0.6%. The gene order was gi-3, Mf-1, N-1. Key words: Oat, Avena sativa, genetics, giantism, hullessness, multiflorous spikelet

Linkage of stem rust resistance gene Sr33 and the gliadin (Gli-D1) locus on chromosome 1DS in wheat

A gene for stem rust resistance, Sr33, backcrossed into 'Columbus' wheat was linked with the gliadin locus on chromosome 1DS with a recombination value of 9.0 ± 3.2%. No major quality differences were apparent in the comparison of the two gliadin alleles associated with Sr33.Key words: linkage, Sr33, gliadin alleles, quality.

Linkage exclusion between the autosomal dominant polycystic kidney disease locus and chromosome 16 markers in a new family.

A family segregating for autosomal dominant polycystic kidney disease (ADPKD) is reported. The clinical picture was typical for ADPKD in some family members, although others showed mild involvement. DNA from family members was probed with seven chromosome 16 single-copy DNA sequences that mapped to the telomere of the short arm of the chromosome. The most likely order of six of the probes from the telomere is palpha3'HVR.64 at the designated locus D16S85, CRI-0327 at D16S63, CRI-090 at D16S45, CRI-0129 at D16S56, CRI-0133 at D16S58, and CRI-0136 at D16S60, with the PKD1 locus for ADPKD between D16S85 and D16S63. The seventh probe 24-1 at D16S80 had not been ordered in relation to the other sequences, but PKD1 had been mapped between it and D16S85. The three probes that were informative in our family, palpha3'HVR.64, CRI-090, and CRI-0136 had been linked to the disease locus at recombination frequencies of 4% and approximately 6 and 12%, respectively. Linkage was excluded between the ADPKD locus in our family and palpha3'HVR.64 at a recombination value of up to 6%. Linkage was also excluded between CRI-090 and the disease locus at a recombination value of up to 5%. The data for linkage between CRI-0136 and the ADPKD locus in our family were inconclusive. Multipoint analysis excluded the possibility that the disease in this family lies between the flanking genetic markers that have previously been used to define the genetic interval in which the most common form of polycystic kidney disease, PKD1, lies. We have not made a positive assignment of the ADPKD mutation in this family.(ABSTRACT TRUNCATED AT 250 WORDS)

Genetic linkage of the Adh1 and W1 loci in soybeans

Four crosses were made among seven soybean cultivars for determining possible linkage between Adh1 and W1 loci. An examination of F2 seed indicated that these loci are linked with a recombination value of 20.6 ± 1.2%. These loci are located in linkage group 8. Key words: soybean linkage, isozymes, alcohol dehydrogenase (Adh1), color locus (W1), Glycine max.

Chromosome location and linkage of a new gene (Lr33) for reaction to Puccinia recondita in common wheat

A gene for resistance to Puccinia recondita, originally detected in wheat (Triticum aestivum L.) accessions PI58548, PI268454, and PI268316, has been located on the long arm of chromosome 1B, 3.1 ± 1.2 crossover units from the centromere. In a cross between the backcross line RL6057 containing this new gene, now designated Lr33, and the backcross line RL6078 containing gene Lr26, gene Lr33 is closely linked to gene Lr26 (or the translocation breakpoint) with an estimated 2.6 ± 0.8 recombination value. RL6057 and RL6078 differ in gliadin bands that are controlled by genes on the short arm of chromosome 1B or 1R. The banding difference was completely associated with the presence or absence of Lr26. Key words: Triticum, Puccinia, linkage.

INHERITANCE OF THREE AUTOSOMAL MUTATIONS IN THE COLORADO POTATO BEETLE LEPTINOTARSA DECEMLINEATA (COLEOPTERA: CHRYSOMELDIAE)

A mutant Colorado potato beetle, Leptinotarsa decemlineata (Say), with white-body and pearl-eye was isolated. Karyotype analysis showed that the No. 2 chromosomes of the mutant are of the acrocentric race. Reciprocal crosses of the mutant with a metacentric race of the wild type revealed that both the white-body and pearl-eye are due to single autosomal recessive genes that are not allelic but segregate independently from each other. The pericentric inversion of No. 2 chromosomes is a stable mutation that followed Mendelian segregations in the F2 hybrids. Hybrids showed normal meiotic pairing. Chiasma frequency analyses indicated that the female parent influenced the recombination value of the hybrids.