Homozygous Recessive Condition Research Articles

Наследование признака высокого содержания олеиновой кислоты в масле семян F2 и поколения BC1 рапса озимого (Brassica napus L.)

The aim of the work was to study the patterns of inheritance of the trait of high oleic content in the F2 and generation BC1 of winter rapeseed in order to obtain new knowledge about the genetic mechanisms of the high oleic acid contents in seed oil and scientifically based approaches to the development of the breeding germplasm with a high content of oleic acid. The studies were carried out in 2021– 2022 in the field. The material was reciprocal F1 hybrids from crossings of the high-oleic line VN-1848 (79.3%) and two lines from the cultivars Sarmat and Selegor of VNIIMK breeding with the traditional content of oleic acid in seed oil – 62.1 and 60.5%, respectively. Hybrids F1 were used to produce BC1 seeds. F2 and BC1 generations were obtained in 2022. In F2 hybrids, splitting into two phenotypic classes was observed in a ratio of 15 : 1. The first one included lines with oleic acid content in seed oil less than 79%, the second one – lines with high rates of this trait at the level or higher than the parental high-oleic component (18 : 1 > 79%). This proposes the control of a trait by two pairs of non-allelic genes with an additive effect. As a result of backcrosses using the high-oleic lines VN-1848 as the maternal component, 55 genotypes with a low content of oleic acid (18 : 1 < 79%) and 11 genotypes with high levels of this trait (18 : 1 > 79%) were obtained. This corresponded to a splitting ratio of 3 : 1. All χ2 values turned out to be less than 3.8, p > 0.05.The results of the studies confirm our assumption that the oleic acid content in seed oil is controlled by two pairs of non-allelic genes; the manifestation of this trait in plants is observed only when all alleles are in a homozygous recessive state.

Inheritance of resistance to Mungbean Yellow Mosaic Virus (MYMV) in mungbean [Vigna radiata L. Wilczek

Six basic populations (P1, P2, F1, F2, B1 and B2) of 12 crosses involving two resistant and six susceptible mungbean genotypes were screened to study the inheritance pattern of MYMV resistance. All the 12 F1s were susceptible indicating that the susceptibility is dominant over resistance. The F2’s of each of the 12 crosses exhibited a segregation ratio of 9S: 3MS: 3MR:1R indicating the involvement of two recessive genes (r1 and r2) in the inheritance of MYMV resistance. When both genes were present together in a homozygous dominant state, R1- R2, plants were highly susceptible (S). In contrast, when both the genes were in homozygous recessive condition, r1r1,r2r2, the resistant reaction was obvious. However, when one gene was in homozygous recessive (R1,r2r 2) condition, moderate susceptibility (MS) was observed while, when the other gene was in homozygous recessive (r1r1, R2), condition, moderate resistant (MR) reaction was observed. Thus, the F2 segregation, 9 (R1R2): 3 (R1r2r 2): 3 (r1r1R2-): 1 (r1r1r2r 2), was explained on the basis of phenotypic expression, 9S: 3MS: 3MR:1R, which was further confirmed in a back cross generation. Key words: Mungbean, Inheritance, MYMV, Resistance

Wal Mutant Mice Have a Mutation Associated with Autism Spectrum Disorders.

The waved alopecia (wal) mutation arose spontaneously in mice. Phenotypically, the wal mutation in a homozygous recessive state is manifested by a wavy coat. Over time, partial baldness develops, which leads to a thinning of the coat in mice. The molecular nature of the genetic defect in wal is still unknown; however, the coordinates of the chromosome locus in which the wal gene is located, a section of about 107 bp in length, has been determined in mouse chromosome 14. We examined the wal locus by sequencing the exons of candidate genes in which the mutation was expected, and performed genome-wide sequencing to identify the cause of the wal mutation. The sequences of exons of candidate genes located in this region did not carry changes that could lead to a change in the structure of the protein. However, outside the wal zone, a mutation in the Slc9a9 gene was found that is probably not associated with the wal phenotype. According to the literature, a mutation in the Slc9a9 gene leads to autism spectrum disorders. This is the first discovered spontaneous mutation in the Slc9a9 gene in mice.

Evaluation of some Tomato Genotypes for Nematode Resistance and Detection of the Mi-1.2 Resistance Gene

Response of fourteen tomato genotypesfrom different geographical regions to root-knot nematodes (RKN; Meloidogyne spp .) was evaluated for two seasons under greenhouse conditions. Two PCR-based markers (Mi-23 and REX-1) were used for the detection of the RKN resistance gene (Mi-1.2) in the tested genotypes. The results showed a wide variation among tested tomato genotypes in their responses to RKNs. Highly significant differences were observed among tested genotypes for gall index and egg masses per root system. Based on nematode bioassay, the tomato genotype Strain B F1 was highly resistant to RKN and ranked in top of resistant genotypes. Floradade and VF145-B were resistant, Castlerock, Peto86 and Qaha were moderately resistant, Super strain B, E115, Super Marmande, M82 and Edkawy were susceptible, and E37, E40 and Giza-80 were highly susceptible to RKN. Molecular analysis with Mi23 and REX-1 markers indicated a heterozygous state (Mi/mi) of Mi-1.2 gene for Strain B F1; meanwhile, the remaining genotypes displayed a homozygous recessive state (mi/mi). These finding suggested that Strain B F1 could be used to develop new tomato cultivars resistant to RKN through tomato breeding programs. In addition, the results suggested that tomato genotypes that were identified in the present study as homozygous recessive (mi/mi) for the Mi-1.2 gene and considered as resistant or moderately resistant may possess other genes controlling RKN resistance. However, further studies are still needed to determine these genes that control the resistance to RKNs in tomatoes.

Genetic control of reproductive and fruit quality traits in crosses involving cultivars and induced mutants of tomato (Solanum lycopersicum L.)

Development of mutants and their effective utilization to incorporate desirable traits in tomato would be a sound improvement strategy to develop so called 'smart' tomato variety of the coming century. Initially we developed three induced mutants from two varieties, 'Patharkuchi', a local adapted cultivar and an introduced variety 'Berika', and then three crosses (Berika 9 P Mut-5, Berika 9 P Mut-11, Patharkuchi 9 B Mut-1) were made to involve in these two varieties and their respective mutants. Six generations (P1, P2, F1, F2, BC1 and BC2) of three crosses were utilized to study the genetic control of yield and quality traits, and to study the genetic basis of formation of dark green fruit. The nature and magnitude of gene action controlling the inheritance of 27 quantitative traits differed from one cross to another and from one trait to another, mostly conditioned by nonadditive gene action and duplicate epistasis. The prevalence of duplicate epistasisin three crosses for most of the traits revealed that the pace of progress through conventional selection process would be hindered as this kind of epistasis might result in decreased variation in F2 and subsequent generations. Recurrent selection in biparental progenies would be helpful for exploiting this type of nonallelic interaction through generation of high frequency of desirable recombination and concentration of genes having cumulative effects in the population. We also observed complex genetic behaviour of some of the traits revealing significant epistatic components. Inheritance study of 'dark green fruit' (dg1) of Berika 9 P Mut-5 cross revealed a single recessive gene governing the trait and expressed when the mutant gene was in homozygous recessive condition (designated as dg-1/dg-1).

Genetic analysis of gene‐specific resistance to mungbean yellow mosaic virus in mungbean (Vigna radiata)

AbstractSix intervarietal crosses involving two resistant and three susceptible genotypes of mungbean were attempted with the objectives to determine the mode of inheritance of gene‐specific Mungbean Yellow Mosaic Virus (MYMV) resistance. An infector row technique along with artificial inoculation was used for evaluating parents, F1, F2 and F3 plants for MYMV resistance. Disease scoring for MYMV indicated that F1s were highly susceptible as were the susceptible parents while resistant parent exhibited resistant reaction. The F2 progeny segregated in the ratio of 9 S:3 MS:3 MR:1 R suggesting that the resistance was governed by digenic recessive genes (rm1 and rm2). When one gene (rm1) was present in the homozygous recessive condition in different plants, it conferred moderately susceptible (MS) reaction, whereas when other gene (rm2) was in homozygous condition, moderately resistant (MR) reaction was obvious. When both genes (rm1 and rm2) were present together in the homozygous recessive condition, resistant reaction (R) was observed. The F2 segregation explained on the basis of phenotypic expression was further confirmed by F3 segregation.

Analysis of strawberry genetic collection (Fragaria L.) for Rca2 and Rpfl genes with molecular markers

Strawberry (Fragaria x ananassa Duch.) varieties are susceptible to many fungal diseases. Identification of forms, carrying resistance genes, is an important stage in breeding programs leading to resistant varieties. The use of molecular markers allows to determine with high reliability the presence of the necessary genes in the genome and to identify promising forms. Some of the common strawberry's diseases, causing significant damage to strawberry plantations, are anthracnose (Colletotrichum acutatum Simmonds) and red stele root rot (Phytophthora fragariae var. fragariae Hickman). Dominant Rca2 gene is involved in monogenic resistance to C. acutatum pathogenicity group 2. Rpf1, Rpf2, Rpf3 genes are determined in monogenic resistance to red stele root rot. The purpose of this study was molecular genetic testing genotypes of genus Fragaria L. to identify carriers of Rca2 allele anthracnose resistance and Rpf1 allele red stele root rot resistance. The objects of study were the wild species of the genus Fragaria L. and strawberry varieties (Fragaria x ananassa Duch.) of different ecological and geographic origin. To assess allelic state Rca2 anthracnose resistance gene the dominant SCAR marker STS-Rca2_240 was used, was linked to the resistance gene Rca2 with a genetic distance of 2.8 cM. Rpf1 gene red stele root rot resistance was identified with the dominant SCAR marker R1A, was linked to the resistance gene Rpf1 with a genetic distance of 3.0 cM. The resistant allele of the marker STS-Rca2_240 was identified in the Laetitia variety (Rca2Rca2 or Rca2rca2 genotype), which allows us to recommend it as a promising source in breeding for anthracnose resistance. The other studied forms have homozygous recessive state of the marker STS-Rca2_240 (putative genotype rca2rca2). The resistant allele of the marker SCAR-R1A in the varieties and wild species of strawberry under study is absent, which presumably indicates their homozygous recessive genotype of Rpf1 gene (rpf1rpf1).

Compound Heterozygosity of β-Thalassemia and the Sickle Cell Hemoglobin in Various Populations of Chhattisgarh State, India

Hemoglobinopathies evolved as a protective mechanism against malaria, which exhibit selective advantage in the heterozygous state. However, in a homozygous recessive condition, it poses a serious socioeconomic burden. Sickle cell anemia is an autosomal recessive hemoglobinopathy associated with erythrocytes sickling, vaso-occlusive crisis (VOC), as well as multi-organ failure and death. The coinheritance of other hemoglobinopathies is known to substantially modulate the clinical manifestation of sickle cell anemia. In the present study, we aimed to analyze the coinheritance of β-thalassemia (β-thal) in Hb S (HBB: c.20A>T) patients. The study includes 918 sickle cell anemia patients from 10 ethnic populations of Chhattisgarh State, India. Complete blood counts (CBCs) and hemoglobin (Hb) high performance liquid chromatography (HPLC) fractionation data were collected from patient record books. We observed Hb S-β-thal in all the analyzed populations. Interestingly, high frequencies of Hb S-β-thal have been observed in Satnami (53.8%), Rawat (47.1%), Gond (35.1%) and Panika (30.6%) populations. Inter-population comparison of hematological parameters [Hb F (p < 0.001), Hb A2 (p < 0.001), Hb (p = 0.03) and red blood cell distribution width (RDW) (p < 0.001)] revealed significant differences. We also observed that mean Hb F levels were significantly higher in Hb S compared to Hb S-β-thal patients in the respective populations. Our study highlights the higher prevalence of β-thal as well as the compound heterozygosity for Hb S and β-thal in various populations of Chhattisgarh State, India.

Exome sequencing identifies a novel TTC37 mutation in the first reported case of Trichohepatoenteric syndrome (THE-S) in South Africa

BackgroundTrichohepatoenteric syndrome (THE-S) or phenotypic diarrhoea of infancy is a rare autosomal recessive disorder characterised by severe infantile diarrhoea, facial dysmorphism, immunodeficiency and woolly hair. It was first described in 1982 in two infants with intractable diarrhoea, liver cirrhosis and abnormal hair structure on microscopy. We report on two siblings from a consanguineous family of Somali descent who, despite extensive clinical investigation, remained undiagnosed until their demise. The index patient died of fulminant cytomegalovirus pneumonitis at 3 months of age.MethodsWhole exome sequencing (WES) was performed on a premortem DNA sample from the index case. Variants in a homozygous recessive state or compound heterozygous state were prioritized as potential candidate variants using TAPER™. Sanger sequencing was done to genotype the parents, unaffected sibling and a deceased sibling for the variant of interest.ResultsExome sequencing identified a novel homozygous mutation (c.4507C > T, rs200067423) in TTC37 which was confirmed by Sanger sequencing in the index case. The identification of this mutation led to the diagnosis of THE-S in the proband and the same homozygous variant was confirmed in a male sibling who died 4 years earlier with severe chronic diarrhoea of infancy. The unaffected parents and sister were heterozygous for the identified variant.ConclusionsWES permitted definitive genetic diagnosis despite an atypical presentation in the index case and suggests that severe infection, likely secondary to immunodeficiency, may be a presenting feature. In addition definitive molecular diagnosis allows for genetic counseling and future prenatal diagnosis, and demonstrates the value of WES for post-mortem diagnosis of disorders with a non-specific clinical presentation in which a Mendelian cause is suspected.

Genetic control of fruit yield and quality characters in tomato genotypes possessinghp-1,ogc,dg,Aftandringenes

Five inbred lines of tomato possessing one each of the specific genes viz., hp-1, ogc, dg, Aft and rin were crossed in a half diallel fashion to determine the combining ability and gene action of fruit yield/plant, fruit weight and eight important fruit quality characters. Additive genetic component was predominant for TSS, ascorbic acid and anthocyanin contents; both additive and non-additive components was important for fruit yield/plant, fruit weight and lycopene content, and non-additive gene action was overwhelmingly important for pericarp thickness and total sugar content while estimates of both the genetic components was zero for titrable acidity and β-carotene content of fruit. General combining ability effects of the parents corresponded well to their per se performance. Homozygous recessive condition of the genes, hp-1, ogc, dg governed enhanced lycopene content in the fruits. Homozygous Aft/Aft plant had higher anthocyanin content in the fruit than the heterozygous plant indicating additivity of the Aft gene in expressing the character. The hybrid of two widely divergent parent BCT-115 dg/dg x Alisa Craig Aft/Aft emerged as outstanding for both fruit yield and quality which also opened up the possibility of developing tomato hybrid rich in both lycopene and anthocyanin contents. The hybrid BCT-115 dg/dg x BCT-111 rin/rin was also promising for commercial utilization.

Molecular diagnosis of inherited retinal diseases with non-specific clinical phenotypes using whole exome sequencing

The inherited retinal disorders are very difficult to classify due to their progressive nature and similar clinical symptoms. In this report we have demonstrated differential diagnosis of retinal diseases that would otherwise not have been suspected based on the nonspecific clinical presentation in a patient of Western Asia origin. He was clinically diagnosed as Retinitis Pigmentosa. We observed two pathogenic mutations associated with Bietti crystalline dystrophy (BCD) and conerod dystrophy 13 (CORD13) respectively. Based on the Whole exome sequencing (WES) results, we demonstrated that patient carries mutation of CYP4V2 gene, which might lead to BCD in autosomal homozygous recessive state. WES enabled the identification and differentiation of inherited retinal diseases, which otherwise would have been misdiagnosed. WES not only enhances our present understanding of genetic basis of retinal disorders but also provides insight to carry out further investigation for similar cases. Therefore, WES has very good clinical utility and clinical significance in the differential molecular diagnosis of genetic diseases.

Inheritance of Aposporous Apomixis in Inter‐specific Hybrids Derived from Sexual Paspalum plicatulum and Apomictic Paspalum guenoarum

ABSTRACTApomictic Paspalum plicatulum Michx. and P. guenoarum Arechav. are promising candidates for forage grass development in tropical regions. From a plant breeding perspective, apomixis provides a unique mechanism for developing superior cultivars and preserving them indefinitely. Therefore, analysis of its inheritance is of great interest in these apomictic species. The objective of this work was to analyze the inheritance and expressivity of apomixis in interspecific families derived from crosses between a sexual colchicine‐induced plant of P. plicatulum and an apomictic P. guenoarum plant. One F1, one F2, and three backcross (BC) populations were created. Amplified fragment‐length polymorphism (AFLP) markers confirmed the hybrid origin of the F1 descendants. Analysis of the reproductive mode of the F1 by flow cytometry seed screen (FCSS) showed a segregation ratio of 1.6:1 sexual vs. apomictic plants. The same analysis in F2 and BC populations showed that in selfing or crosses involving sexual genotypes all progeny reproduced by sexuality, while BC populations involving apomictic hybrids as pollen donors produced offspring that segregated for the reproductive mode. Apomixis can be transmitted by pollen from P. guenoarum to other species of the Plicatula group as a simplex (Aaaa) Mendelian dominant factor, and full sexual reproduction requires the homozygous recessive (nulliplex) condition (aaaa) for the apomixis determinant. Results provided here are of interest for breeding apomictic species of Plicatula and for basic research on the genetic determinants of apomixis. Also, the possibility of creating new apomictic cultivars by traditional breeding methods is presented.

A molecular assessment of the genetic model of spathe color inheritance in Anthurium andraeanum (Hort.)

Past genetic studies have shown three independent loci designated O, R and M control spathe color in Anthurium andraeanum (Hort.). To evaluate the genetic model and to understand the control of anthocyanin biosynthesis at the molecular level, the expression of the anthocyanin biosynthetic genes, CHS, F3H, DFR, ANS and F3'H, was examined at the mRNA and protein levels and correlated to anthocyanin content and spathe color in eight genetically characterized anthurium cultivars representing different states of the O, R and M loci. The results showed that the expression of F3H and ANS was co-regulated by a putative transcription factor encoded by the R locus, and the expression of DFR was regulated by a putative transcription factor encoded by the O locus. White cultivars, which were in the homozygous recessive state for either O or R or both, exhibited reduced expression of the anthocyanin biosynthetic genes and hence had negligible levels of anthocyanin. Cultivars that were mm displayed reduced expression of F3'H suggesting that it may either encode a defective form of the F3'H gene or a regulator that controls its expression. Additionally, a correlation between anthocyanin abundance and the expression of F3'H in the red cultivars suggested that F3'H expression may be a key control point in the regulation of anthocyanin biosynthesis in anthurium and hence plays a major role in influencing the shade intensity in red cultivars. These findings provide evidence in support of the genetic model for color inheritance in the spathe.

Genetic analysis of resistance to mungbean yellow mosaic virus in mungbean (Vigna radiata)

With 1 figure and 3 tables Abstract Mungbean yellow mosaic virus (MYMV) causes one of the most destructive diseases in mungbean. The objectives of this study were to determine the inheritance of MYMV resistance and to identify the role of each resistance gene. Six crosses between resistant and susceptible genotypes were attempted. An infector row technique was used for evaluating parents, F1 and F2 plants for MYMV resistance. Segregating populations were classified into four reactions viz. susceptible (S), moderately susceptible (MS), moderately resistant (MR) and highly resistant (R) based on the distribution and severity of symptoms. The F1 plants from all six crosses and the susceptible parents showed S reactions, while resistant parents showed R reactions. The segregation of resistance responses in F2 populations in ratios of 9 S : 3 MS : 3 MR : 1 R suggested that the resistance was governed by two recessive genes. When one gene was present in the homozygous recessive condition in different plants, it conferred MR and MS reactions. When both genes were present together in the homozygous recessive condition, plants produced resistant reactions (R).

Multiple Endocrine Neoplasia Type I Variants and Phenocopies: More than a Nosological Issue?

Multiple endocrine neoplasia type I (MEN1) is a rare hereditary tumor syndrome, transmitted as an autosomal dominant trait, caused by mutations in the MEN1 gene encoding menin, a 610-amino-acid tumor suppressor protein, widely expressed in both endocrine and nonendocrine tissues (1). In fact, MEN1 patients display a large spectrum of benign and malignant endocrine lesions, including hyperparathyroidism as well as pituitary and enteropancreatic tumors, and also nonendocrine tumors (e.g. lipomas, skin tumors, and meningiomas). Germline heterozygous loss-of-function mutations are generally found in MEN1 patients, and additional somatic loss of heterozygosity in the MEN1 locus leads to the lack of both MEN1 alleles in tumors, with acquisition of a homozygous recessive state at the tissue level (2, 3). MEN1 syndrome frequently exhibits a familial pattern, whereas only the minority of affected individuals present as a simplex, or sporadic, case defined as a single occurrence of MEN1 syndrome in a family. Generally, MEN1 germline mutations are identified with an average prevalence of 70% in the familial forms, whereas the sporadic cases, associated with de novo mutation of the MEN1 gene, represent about 10% of cases. According to this, a crucial issue is still represented by some clinical phenotypes presenting as a MEN1-related status in which MEN1 gene analysis failed to detect germline mutations: MEN1 variants and MEN1 phenocopies. MEN1 variants can be defined as differing clinical expressions from one gene such as familial isolated hyperparathyroidism (FIHP) in which germline mutations in MEN1 gene have been reported with a different prevalence in families with FIHP (4–6). Instead, a MEN1 phenocopy consists of a trait that strongly resembles a MEN1 phenotype in a patient or a family without identified MEN1 mutation and not related to the gene itself (7). A practical example could be a case of FIHP in which MEN1 mutation analysis results negative, being caused by mutation in another familial hyperparathyroidism-related gene, such as either the calcium-sensing receptor gene (8), whose inactivating mutations account for familial hypocalciuria hypercalcemia syndrome, or the HRPT2 gene responsible for the hyperparathyroidism-jaw tumor syndrome (9). Recently described is an interesting small family meeting the criteria of MEN1 but exhibiting atypical MEN1 tumors such as somatotropinoma and renal angiomyolipoma associated to the more typical parathyroid tumors (10). No MEN1 germline mutation was detected in affected members, whereas they had a CDKN1B mutation linked to their MEN1 trait (10). Interestingly, a spontaneous strain of rat shows a similar spectrum of tumors caused by homozygous mutation of Cdkn1b (10). Thus, this phenotype may represent a rare and important phenocopy of classic MEN1, but more families will need to be studied to understand the complete phenotype. Concerning the possible causes of nondetection of MEN1 mutation, several points have to be addressed, as also made by Agarwal et al. (11) in this issue of The Journal. First, the germline mutation could rely on regulatory/noncoding regions of the gene, such as the promoter region. Currently, such mutations of the MEN1 gene have not been reported. Second, the germline mutation could consist of a large deletion of MEN1 gene, but it seems to rarely occur, being found in approximately 4% of cases (12, 13). Consequently, the attention of researchers has to be directed to look for other causes that could explain both the MEN1-related clinical phenotype and the nondetection of MEN1 mutation, such as the involvement of other genes. In the last decade, menin has been reported to interact with a multitude of proteins including jun D proto-oncogene, Mothers against decapentaplegic homolog family members, Pem, nuclear factorB, Fanconi anemia complementation group D2, Replication Protein A2, Nonmuscle Myosin IIA, glial fibrillary acidic protein, vimentin, and heat-shock protein 70, although to date none of the interacting partners have been directly proven important in MEN1 pathophysiology (14). Moreover, it has been hypothesized that menin mediates its tumor suppressor action by regulating histone methylation in promoters of HOX genes and/or CDKN2C,CDKN1B, andpossiblyother cyclin-dependent kinase

Genetic control of pungency in C. chinense via the Pun1 locus

Capsaicin, the pungent principle in hot peppers, acts to deter mammals from consuming pungent pepper pods. Capsaicinoid biosynthesis is restricted to the genus Capsicum and results from the acylation of the aromatic compound, vanillylamine, with a branched-chain fatty acid. The presence of capsaicinoids is controlled by the Pun1 locus, which encodes a putative acyltransferase. In its homozygous recessive state, pun1/pun1, capsaicinoids are not produced by the pepper plant. HPLC analysis confirmed that capsaicinoids are only found in the interlocular septa of pungent pepper fruits. Immunolocalization studies showed that capsaicinoid biosynthesis is uniformly distributed across the epidermal cells of the interlocular septum. Capsaicinoids are secreted from glandular epidermal cells into subcuticular cavities that swell to form blisters along the epidermis. Blister development is positively associated with capsaicinoid accumulation and blisters are not present in non-pungent fruit. A genetic study was used to determine if the absence of blisters in non-pungent fruit acts independently of Pun1 to control pungency. Screening of non-pungent germplasm and genetic complementation tests identified a previously unknown recessive allele of Pun1, named pun1(2). Sequence analysis of pun1(2) revealed that a four base pair deletion results in a frameshift mutation and the predicted production of a truncated protein. Genetic analysis revealed that pun1(2) co-segregated exactly with the absence of blisters, non-pungency, and a reduced transcript accumulation of several genes involved in capsaicinoid biosynthesis. Collectively, these results establish that blister formation requires the Pun1 allele and that pun1(2) is a recessive allele from C. chinense that results in non-pungency.

Development of cytoplasmic‐genic male sterility in safflower

AbstractAn interspecific cross was made between Carthamaus oxyacantha and the cultivated species C. tinctorius to develop a cytoplasmic‐genic male sterility (CMS) system in safflower. C. oxyacantha was the donor of sterile cytoplasm. The 3: 1 segregation pattern observed in BC1F2 suggested single gene control with dominance of male‐fertility over male‐sterility. The information obtained from crossing male sterile X male fertile plants in BC1F3 and BC1F4 generations showed statistically significant single gene (1: 1) segregation for male sterility vs. male fertility. The results demonstrated that C. tinctorius possesses a nuclear fertility restorer gene and that a single dominant allele restored fertility (Rf) in progeny carrying CMS cytoplasm of C. oxyacantha. Male sterility occurred with the homozygous recessive condition (rfrf) in a sterile C. oxyacantha cytoplasm background and not in the normal cytoplasm of C. tinctorius. The genetic background of different restorer lines of C. tinctorius having normal cytoplasm did not effect fertility restoration. The absence of male sterile plants in C. tinctorius populations ruled out the possibility of genetic male sterility. Normal meiosis in F1 and BC1F2 ruled out a cytogenetic basis for the occurrence of male sterility.

Development of yellow‐seeded Brassica napus of double low quality

AbstractTwo yellow‐seeded white‐petalled Brassica napus F7 inbred lines, developed from interspecific crosses, containing 26–28% emcic acid and more than 40 μmol glucosinolates (GLS)/g seed were crossed with two black/dark brown seeded B. napus varieties of double low quality and 287 doubled haploid (DH) lines were produced. The segregation in the DH lines indicated that three to four gene loci are involved in the determination of seed colour, and yellow seeds are formed when all alleles in all loci are in the homozygous recessive state. A dominant gene governed white petal colour and is linked with an erucic acid allele that, in the homozygous condition, produces 26–28% erucic acid. Four gene loci are involved in the control of total GLS content where low GLS was due to the presence of recessive alleles in the homozygous condition in all loci. From the DH breeding population a yellow‐seeded, yellow‐petalled, zero erucic acid line was obtained. This line was further crossed with conventional B. napus varieties of double low quality and, following pedigree selection, a yellow seeded B. napus of double low quality was obtained. The yellow seeds had higher oil plus protein content and lower fibre content than black seeds. A reduction of the concentration of chromogenic substances was found in the transparent seed coat of the yellow‐seeded B. napus.

Inheritance and mapping of a light green mutant in cultivated diploid potatoes

A light green mutant was found in a population of adapted cultivated diploid potatoes. Genetic analysis indicates that this trait is controlled by a single nuclear gene. The gene symbol lg is proposed. The segregation ratios fit a pattern which strongly suggest that there is a close linkage between the Lg allele and a locus which confers lethality in its homozygous recessive state. Some crossing over between the lg locus and the lethal was found to occur but LgLg genotypes were not observed in progenies from sib-matings. The lg locus mapped to the potato linkage group VI between the restriction fragment length polymorphism (RFLP) loci CP18 and GP24.

Identification and genetic characterization of different resistance sources to ascochyta blight within the genus Lens

Genetic regulation of host resistance in lentil to ascochyta blight was found to be controlled by two complementary dominant gene pairs in wild species of Lens ervoides and Lens odemensis. Both genes must be present in the dominant form, whether homozygous or heterozygous, for complete resistance. When one pair of genes is present in homozygous recessive state, they mask the effect of the other dominant gene pair and ultimately makes the lentil plant susceptible to the pathogen, a case of duplicate recessive gene interaction. The results also suggested that in Lens culinaris ssp. orientalis, ascochyta blight resistance was controlled by a single dominant gene pair. The possible utilization of wild Lens species to improve the genetic resistance of cultivated lentil to ascochyta blight is reported and it is suggested that interspecific hybrids should be included in lentil breeding programmes aiming at ascochyta blight resistance.