Source Of Male Sterility Research Articles

A genetic male sterile line developed by molecular marker-assisted selection in Chinese cabbage (Brassica rapa ssp. pekinensis)

A multiple allele inherited genetic male sterile line of Chinese cabbage 06s x 110 was used as the source of male sterility, and methods of crossing, backcrossing and selfing were applied to breed the male sterility to male fertile line of Chinese cabbage Y02. The SCAR marker syau-scr04 which linked to the male sterility gene Ms, was applied in the selection of Ms gene. The new male sterile line GMS 4 with similar botanical traits to Y02 with 100% male sterility and 100% male sterile plants, was bred successfully. The accuracy of marker syau-scr04 in determining the plant genotype was 100%. The results indicate that the marker could be applied in the marker-assisted selection of the genetic male sterile line in Brassica crops in B.campestris (AA, n = 10). Key words : Chinese cabbage, marker-assisted selection (MAS), genetic male sterile line, breeding.

Genetic and cytological analysis of a new spontaneous male sterility in radish (Raphanus sativus L.)

A male sterile plant appeared in the radish breeding program at the Hubei Academy of Agricultural Sciences, Hubei, China. In its progeny, a two-type (half of plants male sterile, the other half male fertile) line 01GAB was established. An F2 population of 260 plants from a cross of male-sterile 01GAB and a male fertile line 9802H segregated for male fertility in a 3:1 ratio indicating that fertility was restored by a single dominant gene, here designated RsMs. A PCR-based DNA marker specific to the male fertility Rfob gene in 9802H was absent in 01GAB. Linkage analysis placed the RsMs locus 10.7 cM away from the Rfo locus. In an F2 population of hybrids between 01GAB and male fertile 9802B, a co-dominant DNA marker for the RSultr3.2A (a radish sulfate transporter gene) locus was linked to the RsMs locus at 1.5 cM suggesting that fertility restoration in 01GAB was located in the region with known male sterility restorers in radish. However, no maintainer for the 01GAB source of male sterility has been identified so far. Cytological observations have shown that the abnormalities in male sterile anthers first appeared in tapetum at the tetrad stage, followed by a hypertrophy of the tapetal cells at the vacuolate microspore period. These results suggest that male sterility in 01GAB is likely to be genetic in nature, or it may represent a new type of the cytoplasmic male sterility.

Influence of types of sterile cytoplasm on the resistance to sorghum shoot fly (Atherigona soccata)

With 2 figures and 3 tables Shoot fly Atherigona soccata (Rondani) is one of the most important insect pests affecting sorghum during early stages of crop growth. Commercial production of hybrid seed in sorghums relies on a single source of male sterility (A1) resulting in restricted nuclear genetic diversity of male-sterile (A) as well as restorer (R) lines. Alternative cytoplasms should be exploited to avoid insect pest outbreaks that might be related to the use of single source of cytoplasm. Therefore, this study was carried out to identify the non-milo cytoplasms that are less susceptible to shoot fly. Four isogenic lines in four male-sterile backgrounds, viz. A1, A2, A3 and A4, and their corresponding maintainer (B lines) lines were studied using a fishmeal technique across rainy and postrainy seasons of 2006–07. The A4 cytoplasm was found to be least susceptible to shoot fly as it was comparatively less preferred for oviposition and had lower deadheart formation across seasons than the other cytoplasms tested and thus can be exploited for developing shoot fly-resistant hybrids.

INHERITANCE OF FERTILITY RESTORATION INVOLVING WILD ABORTIVE CYTOPLASMIC MALE STERILITY SYSTEM IN RICE (Oryza sativa L.)

Inheritance of fertility restoration was studied in crosses involving ten elite restorer lines of rice viz. BR6839-41-5-1R, BR7013-62-1-1R, BR7011-37-1-2R, BR10R, BR11R, BR12R, BR13R, BR14R, BR15R and BR16R and one male sterile line Jin23A with WA sources of cytoplasmic male sterility. The segregation pattern for pollen fertility of F2 and BC1 populations of crosses involving Jin23A indicated the presence of two independent dominant fertility restoring genes. The mode of action of the two genes varied in different crosses revealing three types of interaction, i.e. epistasis with dominant gene action, epistasis with recessive gene action, and epistasis with incomplete dominance.DOI: http://dx.doi.org/10.3329/bjpbg.v24i1.16997

Progress in the utilization of Cajanus platycarpus (Benth.) Maesen in pigeonpea improvement

With 1 figure and 4 tablesAbstractCultivated pigeonpea (Cajanus cajan L. Millsp.) has a narrow genetic base; hence, utilization of wild relatives in the crossing programme would broaden its genetic base and introduce useful traits. Cajanus platycarpus (Benth.) Maesen, an annual wild relative from the tertiary gene pool, was successfully crossed with the cultigen, utilizing hormone‐aided pollinations, embryo rescue and tissue culture techniques, and backcrossed using cultigen as the recurrent parent. Advance generation progeny showed a range of useful traits such as resistance to phytophthora blight, pod borer, bruchid and podfly resistance. Variation was also observed for plant type, growth habit and seed colour. A new source of cytoplasmic male sterility was identified in one of the progeny lines. Molecular analysis of the progeny after four backcrosses showed the presence of genomic segments from C. platycarpus accompanied by the presence of recombinant DNA sequences signifying recombination between the parental genomes.

Molecular basis of cytoplasmic male sterility in beets: an overview

Sugarbeet cultivars are almost exclusively hybrids, which are produced using the sole source of cytoplasmic male sterility (CMS), the so-called Owen CMS. Several alternative sources of CMS have been described. One of these, I-12CMS(3), was derived from wild beets collected in Pakistan, and another CMS source, GCMS, has a cytoplasmic origin in wild sea beets from France. During the past decade, male sterility-associated mitochondrial genes have been identified in these three CMS systems. Moreover, the recent development of a variety of DNA markers has permitted the genetic mapping of nuclear restorer-of-fertility genes for both Owen and GCMS. This review focuses on the mechanism of CMS in beets.

Characterization of a male sterile mutant from progeny of a transgenic plant containing a leaf senescence-inhibition gene in wheat

A male sterile plant of wheat (Triticum aestivum L.) segregated from progenies of a transgenic family containing the leaf senescence-inhibition gene PSAG12-IPT in the genetic background of ‘Xinong 1376’, a well adapted winter wheat cultivar. The male sterile plant (named TR1376A) showed no phenotypic changes, except for florets and male organs, compared to its male fertile sibling plants (named TR1376B). The glumes and florets of male sterile TR1376A plants widely opened whereas those of the fertile counterpart TR1376B were closed or opened only briefly at flowing. Anthers of TR1376A were slender and indehiscent, and failed to release pollen. Compared to TR1376B, TR1376A anthers contained greatly reduced amounts of pollen, which was inviable or weakly viable. Ultra-structure studies indicated that cells in the endothecium and middle layers of the anther wall were dissolved or poorly developed in the sterile anthers of TR1376A. Molecular studies showed that the male sterility of TR1376A was caused by a sequence deletion or mutation that occurred in the promoter region of the transgene. F1 hybrids of TR1376A and TR1376B gave 1:1 segregation of male fertility to sterility, indicating that the male sterility of TR1376A was heritable and controlled by a single dominant gene (named Ms1376). To date, only a few dominant nuclear male sterility genes have been characterized and one of them (Ms2) has been successfully used to improve wheat cultivars through recurrent breeding strategies. The discovery of the Ms1376 gene provides another dominant male sterile source for establishing recurrent breeding systems in wheat.

The structure of sterile cytoplasm types within a maize genebank collection

Maize Research Institute (MRI) gene bank maintains a collection of 6000 maize accessions. Within this collection over 100 sources of cytoplasmic male sterility (CMS) were found in field trials, i.e. more than 2% of the total accession numbers. These sources are distributed among Yugoslav open-pollinated varieties (4.56% of them contain CMS), as well as introduced heterozygous genotypes and inbred lines. In order to identify cytoplasm types the gene-bank sources of CMS were screened using a PCR assay with specific primers for C, T and S cytoplasms. Predominant cytoplasmic male sterility type among the analyzed accessions was CMS-S. Results were inconclusive for three accessions, i.e. different results for the progenies of two ears per accession were obtained. For another two accessions a new PCR product profile was identified, consisting of one band characteristic for CMS-S and one unspecific for any of the three CMS types. The PCR approach enabled a simple, fast and reliable large scale screening of maize cytoplasm among MRI gene bank accessions, significantly reducing time for cytoplasm characterizations compared to classical method of testing with restorers for each known type of CMS.

Development of Cytoplasmic-Nuclear Male Sterility, Its Inheritance, and Potential Use in Hybrid Pigeonpea Breeding

Pigeonpea [Cajanus cajan (L.) Millsp.] is a unique food legume because of its partial (20-30%) outcrossing nature, which provides an opportunity to breed commercial hybrids. To achieve this, it is essential to have a stable male-sterility system. This paper reports the selection of a cytoplasmic-nuclear male-sterility (CMS) system derived from an interspecific cross between a wild relative of pigeonpea (Cajanus sericeus Benth. ex. Bak.) and a cultivar. This male-sterility source was used to breed agronomically superior CMS lines in early (ICPA 2068), medium (ICPA 2032), and late (ICPA 2030) maturity durations. Twenty-three fertility restorers and 30 male-sterility maintainers were selected to develop genetically diverse hybrid combinations. Histological studies revealed that vacuolation of growing tetrads and persistence of tetrad wall were primary causes of the manifestation of male sterility. Genetic studies showed that 2 dominant genes, of which one had inhibitory gene action, controlled fertility restoration in the hybrids. The experimental hybrids such as TK 030003 and TK 030009 in early, ICPH 2307 and TK 030625 in medium, and TK 030861 and TK 030851 in late maturity groups exhibited 30-88% standard heterosis in multilocation trials.

A new source of cytoplasmic male sterility found in wild beet and its relationship to other CMS types

We found a number of male-sterile plants in a wild beet (Beta vulgaris L. subsp. maritima) accession line, FR4-31. The inheritance study of the male sterility indicated the trait to be of the cytoplasmic type. The mitochondrial genome of FR4-31 proved to lack the male-sterility-associated genes preSatp6 and orf129, which are characteristic of the Owen CMS and I-12CMS(3) cytoplasms of beets, respectively. Instead, the truncated cox2 gene involved in G CMS originating from wild beets was present in the FR4-31 mitochondrial genome. In Southern hybridization using four mitochondrial gene probes, the FR4-31 cytoplasm showed patterns similar to those typical of the G cytoplasm. It is thus likely that the FR4-31 cytoplasm has a different CMS mechanism from both Owen CMS and I-12CMS(3), and that the FR4-31 and G cytoplasms resemble each other closely. A restriction map of the FR4-31 mitochondrial DNA was generated and aligned with those published for the Owen and normal fertile cytoplasms. The FR4-31 mitochondrial genome was revealed to differ extensively in arrangement from the Owen and normal genomes, and the male-sterile Owen and FR4-31 genomes seem to be derived independently from an ancestral genome.

The argentine wild Helianthus annuus L. genetic resource

Wild Helianthus annuus naturalized in Argentina could be a valuable germplasm source for cultivated sunflower. Five wild populations collected in different environments and with different phenotype expression were evaluated as a genetic resource in a common garden study. The populations showed normal meiosis and produced a good seed set when their plants pollinated the male-sterile inbred line A09 (cms PET1). The wild populations restored more than 80% fertility of the HA89 (cms PET1) and A10 (cms PET1) inbred lines in the F1 generation. The fertility of one male sterile source from Mendoza was restored (>95%) by the maintainer line B10. The fatty acid composition differentiated a population from Entre Rios with a high saturated fatty acid content (>107 g kg-1). Another population from La Pampa showed a high level (>50%) of resistance to the Sunflower Chlorotic Mottle Virus (SuCMoV). No wild populations showed tolerance to imazaphyr sprayed at 2× doses (×=80 g i.a. ha-1). A population collected in the coolest environment showed high tolerance to low temperature (15/5°C, neutral day) in the initial grow stages ( 80%) under water stress (-0.4 MPa) imposed by polyethylene glycol 6000. This population and a second one from southern Buenos Aires showed the lowest leaf temperature increase (<10%) and the highest foliar specific density under artificial drought during the R4 to R6 reproductive stages. It was concluded that wild H. annuus naturalized in central Argentina can supply some useful traits for sunflower breeding.

The Dominant Ms Allele in Onion Shows Reduced Penetrance

The most commonly used source of cytoplasmic male sterility in onion (Allium cepa) is controlled by the interaction of the cytoplasm [male-sterile (S) or normal male-fertile (N)] and one nuclear male-fertility-restoration locus (Ms). Scoring of genotypes at Ms is generally done by testcrossing male-fertile to male-sterile (S msms) plants, followed by scoring of testcross progenies for male-fertility restoration. We identified two N-cytoplasmic families, one that was homozygous dominant and the other segregating at Ms. Plants from each of these two families were individually testcrossed to male-sterile onion. Nuclear restoration of male fertility in testcross progenies was evaluated in the field over 4 years. For male plants homozygous dominant at Ms, we expected testcross families to show 100% male-fertility restoration, but observed mean values between 46% and 100%. For plants segregating at Ms, we again observed lower than expected frequencies of male-fertility restoration. These results demonstrate that the dominant Ms allele shows reduced penetrance, requiring that male-fertility restoration be scored over years to more confidently assign genotypes at Ms.

A Novel Source of Cytoplasmic Male Sterility and a Fertility Restoration Gene in Eggplant (Solanum melongena L.) Lines

‘Taibyo VF’, a Japanese rootstock cultivar, is a Solanum grandifolium × S. melongena hybrid that has difficulty setting seed, but F1 plants of ‘Taibyo VF’ × ‘LS1934’ (S. melongena) produce some seeds. F2 plants were segregated into male-sterile and fertile plants. All plants in the backcross of sterile progeny with S. melongena were sterile, indicating cytoplasmic male sterility (CMS) caused by the S. grandifolium cytoplasm. This CMS is stable under a range of environmental conditions. In contrast, fertile progeny appear to possess a fertility restoration nuclear gene. We studied the inheritance of this gene. F1, F2, and backcross generations from crosses between male-sterile ‘CMS-1’ and fertile ‘FR-1-1’ were obtained. ‘CMS-1’ is the F1 of male-sterile ‘ER98B-10-2-3-1’ × ‘AE-P08’ (S. melongena). ‘ER98B-10-2-3-1’ is the F5 and ‘FR-1-1’ is the F7 of ‘Taibyo VF’ × ‘LS1934’. All ‘CMS-1’ plants were male-sterile; the fertile to male-sterile segregation ratios were 3 : 1 in ‘FR-1-1’, 1 : 1 in F1 and 3 : 1 in F2 of ‘CMS-1’ × ‘FR-1-1’, and 1 : 1 in ‘CMS-1’//‘CMS-1’/‘FR-1-1’. Segregation ratios suggested that fertility restoration is controlled by a single dominant gene (Rf) carried heterozygously in ‘FR-1-1’. Restorer lines that carry nuclear Rf homozygously in the cytoplasm of S. melongena have been developed.

Development of markers for the use of the PEF1 cytoplasm in sunflower hybrid breeding

AbstractThe use of the new cytoplasmic male sterility (CMS) source PEF1 in sunflower hybrid breeding requires markers closely linked to the restorer gene Rf_PEF1 necessary for fertility restoration of hybrids based on the PEF1 cytoplasm as well as diagnostic markers to distinguish the PEF1 cytoplasm from other cytoplasms. Bulked segregant analyses of 256 AFLP primer combinations identified 35 polymorphic primer combinations with 1–3 polymorphisms, resulting in 40 polymorphisms. Eighteen AFLP markers mapped together with the Rf_PEF1 gene covering 119.9 cM. The closest markers, E39M51_300R and E44M56_112A, mapped 3.9 and 6.0 cM to the Rf_PEF1 gene, respectively. Six SSR markers, which belong to the linkage group 13, were screened for polymorphisms between the parental lines. Only ORS630 was polymorphic, but did not map to the same linkage group as Rf_PEF1, indicating that Rf_PEF1 is not located on linkage group 13 where the restorer gene Rf1 for the PET1 cytoplasm is located. Diagnostic markers to distinguish the PEF1 cytoplasm from the PET1 and the fertile cytoplasm in sunflower were obtained using primer combinations for the atp9 gene and orfH522.

Development of a male sterile eggplant by utilizing the cytoplasm of Solanum virginianum and a biparental transmission of chloroplast DNA in backcrossing

To develop a male sterile line of eggplant ( Solanum melongena L.) utilizing the cytoplasm of S. virginianum, an interspecific F 1 hybrid between S. virginianum and S. melongena ‘Senryo Nigou’ was continuously backcrossed to S. melongena ‘Uttara’ using ‘Uttara’ as a recurrent pollen parent and four backcross generations, BC 1, BC 2, BC 3 and BC 4 were produced. All the plants in backcross generations were anther indehiscent although the F 1 hybrid, S. virginianum and S. melongena were dehiscent. Pollen stainability with acetic carmine and in vitro germination ability of pollen in all the backcross progenies were quite lower than those of the parental species. Fruit set percentage, number of seeds per fruit and seed germination rate were high in all the backcross progenies. The present results indicate that anther indehiscent type of functional male sterile line of eggplant could be developed by utilizing the cytoplasm of S. virginianum. PCR-RFLP analysis of chloroplast DNA (cpDNA) and mitochondrial DNA (mtDNA) were performed to identify the organelle inheritance. The F 1 hybrid and all the backcross progenies displayed maternal inheritance of mtDNA. The cpDNA of the examined single BC 1 plant exhibited the recombinant cpDNA pattern of the parental F 1 hybrid and ‘Uttara’, indicating occurrence of the biparental inheritance of cpDNA. As all the BC 2, BC 3 and BC 4 progenies showed the same recombinant cpDNA patterns of the BC 1 plant, the recombinant cpDNA might be stable and harmonize with the nuclear genome of S. melongena. The present male sterile line can contribute to expand the male sterility source of eggplant.

Identification of restorers and maintainers for different cms sources in sunflower using new inbreds

SUMMARY Twelve cytoplasmic male sterile lines belonging to four cytoplasmic male sterility ( cms ) sources were crossed with twelve inbreds to identify fertility restorer lines for each cms source. For the same source differing in line, the inbred behaved as either maintainer/restorer. Out of the twelve new inbred lines tested, fertility was restored in 9 inbreds for DRSF-114A (PEF), DRSF- 132A (PET-2) and DRSF-105A (PET-1), 11 inbreds for DRSF-116A (PEF) and DRSF-127A (CMSI), 4 inbreds for DRSF-115A (PEF), 5 inbreds for DRSF- 125A (CMSI) and DRSF-107A (PET-1), 6 inbreds for DRSF-124A (CMSI), DRSF-131A (PET-2) and 10 inbreds for DRSF-109A (PET-1). However, DRSF- 117A (PEF) was not restored by any of the inbreds tested. The study identified several effective restorers for newly developed cms sources for the first time in India, which can be exploited in developing highly heterotic hybrids possessing alternate cytoplasms. RESUMEN Se cruzaron doce líneas androestériles citoplasmáticas pertenecientes a cuatro fuentes de androesterilidad citoplasmática ( cms ) con doce líneas para identificar líneas restauradoras de la fertilidad para cada fuente de cms . Para cada fuente de cms las líneas se comportaron como mantenedoras o restauradoras. Dentro del conjunto de doce líneas endocriadas, nueve de ellas restauraron la fertilidad en DRSF-11A (PEF), DRSF-132A (PET-2) y DRSF-105A (PET-1), once líneas restauraron en DRSF-116A (PEF), cuatro líneas en DRSF- 115A (PEF), cinco líneas en DRSF-125A (CMSI) y DRSF-107A (PET-1), seis líneas en DRSF-124A (CMSI) y diez líneas en DRSF-131A (PET-2) y DRSF- 109A (PET-1). Sin embargo, ninguna línea restauró la fertilidad en DRSF-117A (PEF). A partir de este estudio, algunos restauradores efectivos pudieron identificarse para fuentes de cms recientemente desarrolladas por primera vez en India, que pueden explotarse en el desarrollo de híbridos altamente heteróticos que poseen citoplasmas alternativos. RÉSUMÉ Douze lignées males stériles développées sur quatre sources cytoplasmiques ( cms ) différentes ont été croisées à douze lignées en vue d’identifier les sources de restauration de la fertilité mâle pour chacune des sources cms . Ces lignées se sont révélées avoir un statut de mainteneur de stérilité ou de restaureur de fertilité variable selon la source de stérilité ou selon la lignée mâle stérile pour une même source. 9 lignées males ont restauré la fertilité de DRSF-114A (PEF), DRSF-132A (PET-2) et DRSF-105A (PET-1); 11 lignées males ont restauré la fertilité de DRSF-116A (PEF) et DRSF-127A (CMSI); 4 lignées males ont restauré la fertilité de DRSF-115A (PEF); 5 lignées males ont restauré la fertilité de DRSF-125A (CMSI) et DRSF-107A (PET-1); 6 lignées males ont restauré la fertilité de DRSF-124A (CMSI); 10 lignées males ont restauré la fertilité de DRSF-131A (PET-2) et DRSF-109A (PET-1).Cependant, aucune lignée testée n’a restauré la fertilité de DRSF-117A (PEF). A partir de cette étude, quelques lignées restauratrices de fertilité ont été identifiées pour les nouvelles sources de stérilité mâle cytoplasmique développées récemment en Inde. Ces résultats peuvent être exploités pour développer des hybrides à fort hétérosis sur des cytoplasmes représentant des alternatives par rapport au cytoplasme couramment utilisé.

Male fertility restoration of wheat in Hordeum chilense cytoplasm is associated with 6HchS chromosome addition

We report a new cytoplasmic male sterility (CMS) source in bread wheat (Triticum aestivum L.) designated as msH1. CMS has been identified during the process of obtaining alloplasmic bread wheat in different Hordeum chilense Roem. Schultz. cytoplasms. It was observed that when using the H. chilense H1 accession, the corresponding alloplasmic line was male sterile. This alloplasmic wheat is stable under different environmental conditions and it does not exhibit developmental or floral abnormalities, showing only slightly reduced height and some delay in heading. On examining microsporogenesis in the alloplasmic line, it was found that different stages of meiosis were completed normally, but abnormal development occurred at the uninucleate-pollen stage at the first mitosis, resulting in failure of anther exertion and pollen abortion. Fertility restoration of the CMS phenotype caused by the H. chilense cytoplasm was associated with the addition of chromosome 6HchS from H. chilense accession H1. Thus, some fertility restoration genes appear to be located in this chromosome arm. Considering the features displayed by the msH1 system, we consider that it has a great potential for the development of viable technology for hybrid wheat production.

An analysis of heterotic potential for agronomically important traits in sunflower (Helianthus annuus L.)

SUMMARY Study of inbreeding and heterosis in sunflower has been taking place for over 80 years now. Practical application of the phenomenon of heterosis in this species began after the discovery of a suitable source of cytoplasmic male sterility in 1969 and that of restorer genes. Many authors have reported significant manifestation of heterosis for seed yield and yield components as well. Also, the mode of inheritance of agronomically important traits in the F1 and F2 generations has been thoroughly examined. Positive correlations for yield have been established between parental lines and F1 hybrids. The GCA and SCA for yield and yield components have been well studied. Solutions have been suggested on how to increase the harvest index and sink capacity as well as the contributions of individual physiological parameters in the process of yield augmentation. In order to increase heterotic effects for seed yield and oil yield and direct and indirect yield components, it is necessary to increase the genetic variability of pre-breeding materials, achieve improved efficacy at the inbreeding stage, and streamline and accelerate the process of GCA and SCA evaluation using molecular markers and other biotechnology methods in order to achieve breeding goals. Seed oil content should be increased to over 55% using recurrent selection methods. Special focus in breeding programs should be placed on the development of high-oleic hybrids (>95%) with a high genetic potential for oil yield, resistance to the dominant diseases, and wide environmental adaptability that would be used for industrial purposes (production of biodiesel, or hydrogen). In order to extent the duration of sunflower oil stability, beta, gamma and delta tocopherols should be incorporated instead of alpha ones alongside the Ol genes. The exiting genetic variability of the cultivated sunflower makes it possible to develop hybrids with a genetic potential for seed yield of over 6 t/ha and seed oil content of over 55%. Most often, however, sunflower yields obtained in large-scale commercial sunflower production are in the 1.5-3.0 t/ha range. There are multiple limiting factors preventing the reali

A YA-type cytoplasmic male-sterile source in common wheat

A new cytoplasmic male-sterile (CMS) system for hybrid wheat breeding, YA-type CMS line with the cytoplasmic mutant from the common wheat variety 'CA8057', was developed by the Institute of Genetics and Developmental Biology, Chinese Academy of Sciences. The pollen sterility of YA-type CMS line was easily maintained but difficult to restore. Some sterile lines with desirable agronomic performance, such as msYA-'CA8057' (BC 17 ), msYA-'Yuandong 6' (BC 9 ), msYA-'Jin 411'(BC 9 ), msYA-'WLI' (BC 10 ), msYA-'Yanshi 9' (BC 10 ), msYA-'BPml6' (BC 9 ), msYA-'Jindong 8' (BC 9 ) and msYA-'Jinmai 33' (BC 9 ), were bred and a restorer line GR1 was screened with 26 new restorer lines being developed by transferring restorer genes from GR1. It was found that abnormal phenomena occurred at the uninucleate-pollen stage and the abortive pollen was poor in starch content and other components. The variance analysis of agronomic traits in eight sterile lines indicated that there was no general negative effect of cytoplasm. The genetic analysis for fertility restoration showed that two pairs of independent major genes (designated YARf 1 YARf 1 YArf 2 YArf 2 ) and some minor genes could be involved in the fertility restoration in restorer line GR1, and YARf 1 was epistatic over YARf 2 for the genetic effect of fertility restoration. As a new CMS system, the YA-type CMS line was of potential value for hybrid wheat breeding and should be further studied.

Identification of sterile cytoplasm (CMS) in maize by using specific mtDNA primers

Thirty sources of cytoplasmic male sterility (CMS) from Maize Gene Bank "Zemun Polje", distributed among Yugoslav OP varieties, have been tested for the presence of particular type of cytoplasm by a single seed multiplex PCR approach with specific primer pairs for T, C and S type cytoplasm. Combination of three pairs of primers in a single PCR reaction, corresponding to the chimeric regions of mtDNA sequences specific for each type of CMS, allowed reliable identification of the major CMS types. Dominant presence of S type cytoplasm was detected. For sources where there is no clear identification of the type of CMS (absence of the PCR band) there is a reasonable doubt that it could be a new, yet unidentified type of CMS.