Identification of stable maintainer and fertility restorer lines for 'Polima' CMS in Brassica campestris

‘Polima’ cytoplasmic male sterility (CMS) was transferred from ‘Polima’ Brassica napus ‘ISN 706’to five different cultivars of Brassica campestris (‘Pusa kalyani’, ‘Pant toria’, ‘Candle’, ‘Tobin’ and ‘ATC 94211′) by repeated backcrossing. It was observed that, while ‘Polima’ CMS manifested complete and stable male sterility in the nuclear backgrounds of ‘Pusa kalyani’, ‘Pant toria’, and ‘Tobin’, the cultivars ‘Candle’ and ‘ATC 94211’possessed the restorer gene for this CMS in the heterozygous condition. An analysis of F₁ and F₂ generations of ‘Polima’‘Pusa kalyani’בCandle’ and ‘Polima’‘Pusa kalyani’בATC 94211’ revealed that restoration is controlled by a single dominant gene. Identification of stable maintainers and restorers of ‘Polima’ CMS could facilitate the development of hybrid varieties in B. campestris.     

Identification and Inheritance of Fertility Restorer Genes for 'tour' CMS in Rapeseed (Brassica napus L.)

Eighteen genotypes of Brassica napus were crossed to a cytoplasmic male sterile (CMS) line of B. napus BO 15 carrying B. tournefortii cytoplasm (‘tour’ cytoplasm). Fourteen genotypes were found to be stable maintainers of the ‘tour’ CMS. Of the remaining four genotypes, GSL-1 and ‘Asahi-natane’ were found to be heterozygous and ‘Mangun’ and ‘Yudal’ were homozygous for the restorer gene. Analysis of the F₁ and F₂ progenies of (CMS) BO 15 בMangun’ and (CMS) BO 15 בYudal’ showed that fertility restoration is controlled by a single dominant gene. The availability of a number of stable maintainer lines and the simple inheritance pattern of fertility restorer gene makes ‘tour’ CMS a useful system for hybrid seed production in rapeseed.     

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’ (BC₁₇), msYA‐‘Yuandong 6’ (BC₉), msYA‐‘Jin 411’ (BC₉), msYA‐‘WL1’ (BC₁₀), msYA‐‘Yanshi 9’ (BC₁₀), msYA‐‘BPm16’ (BC₉), msYA‐‘Jindong 8’ (BC₉) and msYA‐‘Jinmai 33’ (BC₉), 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 YARf₁YARf₁YArf₂YArf₂) and some minor genes could be involved in the fertility restoration in restorer line GR1, and YARf₁ was epistatic over YARf₂ 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.     

Cytoplasmic male sterility with self-incompatibility,a novel approach to utilizing heterosis in rapeseed (<Emphasis Type="Italic">Brassica napus</Emphasis> L.)

The Polima cytoplasmic male sterility (CMS) system has been successfully used in three/two-line hybrid production in rapeseed (Brassica napus L.). However, the sterility of the Polima (pol) CMS lines is sensitive to temperature fluctuations. Also, traces of pollen can cause self-pollination within the CMS lines, which results in reduced levels of F₁ hybrid seed purity and leads to a significant yield loss. Self-incompatibility (SI) is another important approach for hybrid seed production in rapeseed. Despite having a wide range of restorers and being easily selected in a breeding program, SI system has some drawbacks. In this study, SI genes from a self-incompatible line of Brassica napus were transferred to a pol CMS line and S372A, a novel line of combined cytoplasmic male sterility with self-incompatibility was bred. Due to the SI genes, this line produced very few seeds when it was selfed at low temperature and no seeds at high temperature. This suggested that the line with CMS + SI had combined the advantages and overcome the disadvantages of both the pol CMS and SI systems. Furthermore, our results showed that most of the maintainers and all the restorers of the pol CMS system were also maintainers and restorers of the CMS + SI line, respectively. This indicates that the CMS + SI system can be easily used to establish three-line hybrids of rapeseed, and we believe this novel system could be extended to other species of Brassica.     

Establishment of a random-mating population of 'Polima' CMS restorers in Brassica napus by use of dominant genie male sterility

Five restorers of ‘polima’ cytoplasmic male sterility (pol CMS) cannot restore the fertility in dominant genie male sterility (DGMS). A dominant male sterility gene from both, a DGMS line Rs l046AB and DGMS hybrid ‘Zhongza No. 3’, was successfully introduced into Polima cytoplasm. A random-mating population of pol CMS restorers was established by using many double-low pol CMS restorers as pollinators to cross continuously to the DGMS plants which had Polima cytoplasm.     

Inheritance of seed colour in Brassica campestris L. and breeding for yellow-seeded B. napus L.

Summary Seed colour inheritance was studied in five yellow-seeded and one black-seeded B. campestris accessions. Diallel crosses between the yellow-seeded types indicated that the four var. yellow sarson accessions of Indian origin had the same genotype for seed colour but were different from the Swedish yellow-seeded breeding line. Black seed colour was dominant over yellow. The segregation patterns for seed colour in F₂ (Including reciprocals) and BC₁ (backcross of F₁ to the yellow-seeded parent) indicated that the black seed colour was conditioned by a single dominant gene. Seed colour was mainly controlled by the maternal genotype but influenced by the interplay between the maternal and endosperm and/or embryonic genotypes. For developing yellow-seeded B. napus genotypes, resynthesized B. napus lines containing genes for yellow seed (Chen et al., 1988) were crossed with B. napus of yellow/brown seeds, or with yellow-seeded B. carinata. Yellow-seeded F₂ plants were found in the crosses that involved the B. napus breeding line. However, this yellow-seeded character did not breed true up to F₄. Crosses between a yellow-seeded F₃ plant and a monogenomically controlled black-seeded B. napus line of resynthesized origin revealed that the black-seeded trait in the B. alboglabra genome was possibly governed by two independently dominant genes with duplicated effect. Crossability between the resynthesized B. napus lines as female and B. carinata as male was fairly high. The sterility of the F₁ plants prevented further breeding progress for developing yellow-seeded B. napus by this strategy.     

Cytological observation of anther structure and genetic investigation of a new type of cytoplasmic male sterile 0A193‐CMS in Brassica rapa L.

Cytoplasmic male sterility (CMS), a maternally transmitted failure in pollen formation, is an effective pollination control system in hybrid rapeseed (Brassica napus) breeding. However, CMS is not widely used in the related oilseed species Brassica rapa. In the past years, several male sterile plants have been isolated from the B. rapa landrace ‘0A193’, collected in Shaanxi, China, in 2011. It is noteworthy that the fertility expression of 0A193‐CMS was affected by temperature. In contrast to pol CMS, fertility tests with 18 B. rapa and 9 B. napus accessions suggest that a different system of maintaining and restoring is responsible for the observed phenotype. Further on, genetic investigation evidenced that fertility of 0A193‐CMS is controlled by both cytoplasmic and one pair of nuclear recessive genes. Interestingly, plants of the 0A193‐CMS type possess a highly specific fragment of the mitochondrial gene orf222, a crucial regulator of male sterility in nap CMS. Our study broadens the CMS resources in B. rapa and provides a highly applicable alternative to pol CMS and ogu CMS for hybrid breeding production.     

Intergeneric hybridization of Diplotaxis erucoides with Brassica napus. I. cytogenetic analysis of F1 and BC1 progeny

Summary Intergeneric hybrids (F₁) Diplotaxis erucoides (DeDe) x Brassica napus (AACC) and the first backcross to B. napus (BC₁) have been obtained through in vitro culture of excised ovaries. The chromosome numbers of F₁ and BC₁ plants proved the occurrence of unreduced gametes. The study of metaphase I chromosome pairing showed that autosyndesis in De genome and allosyndesis between De and A/C genomes might exist. The male fertility of the F₁ plants was low. Some male-sterile plants were found in F₁ and BC₁ progeny. The possibilities of creating addition lines B. napus-D. erucoides and of obtaining a new cytoplasmic male sterility in B. napus are discussed.     

Conversion of the genic male sterility (GMS) system of bell pepper (Capsicum annuum L.) to cytoplasmic male sterility (CMS)

Non‐pungent bell pepper (Capsicum annuum L.) lacks the cytoplasmic male sterility (CMS) nuclear restorer allele, Rf, and CMS cannot be employed in its F₁ hybrid seed production. To demonstrate that the genic male sterility (GMS) system in non‐pungent bell pepper can be converted to the CMS male sterility system, the conversion of GMS to CMS for non‐pungent bell pepper line GC3 was conducted by introgression of S‐type cytoplasm and the Rf allele from tropical pungent donors. After morphological traits were evaluated, two lines from BC₁F₁ containing S‐type cytoplasm and four lines from BC₂F₂ containing Rf allele, phenotypically similar to GC3, were obtained and could be employed as CMS male sterile lines and restorer lines for non‐pungent bell pepper. Four molecular markers potentially linked to traits of interest were also evaluated in BC₁F₁ and BC₁F₂ populations. This is the first time that GMS has been successfully converted to CMS in bell pepper, a significant contribution for bell pepper hybrid seed production.     

Cytoplasmic Systems in Different Male-Sterile Lines of Rice

In order to characterize the cytoplasmic system in seven cytoplasmic-genic male-sterile lines (CMS; A lines) of rice, viz., V 20A, ‘Zhenshan 97A’, IR 46831A, ‘Madhu A’ (cms-WA), ‘Yar-Ai-Zhao A’ (cms-Gam), ‘Pankhari 203A’ (cms-TN) and Wu 10A (cms-bo) and their isonuclear maintainers (B lines), all possible crosses were made between CMS lines and maintainers (A × B) as well as between the maintainers themselves (B × B). Based on F₁ pollen and spikelet fertility the CMS lines V 20A, ‘Zhenshan 97A’, IR 46831 A, ‘Madhu’ A possessing cms-WA cytoplasm were found to be genetically different from ‘Pankhari 203A’ (cms-TN), Wu 10A (cms- bo) and ‘Yar-Ai-Zhao A’ (cms-Gam) cytoplasms. Cms-bo and cms-TN cytoplasms appeared to be identical. Since the cytoplasms of the A lines are different from those of the B lines, the nuclear genes operating to cause the sterility might also be different in (A × B) and (B × B) crosses.     

Development of cytoplasmic-genic male sterility in safflower

An 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.     

Maternal inheritance of male sterility in the progeny of a natural hybrid between Cajanus lineatus and C. cajan

Adoption of pigeonpea hybrids in central and southern India is showing high impact with on‐farm yield advantages of >30%. The hybrid pigeonpea technology, the first in any legume crop, is based on a cytoplasmic‐nuclear male‐sterility (CMS) system. For a long‐term sustainability of hybrid programme, it is imperative that both nuclear diversity and cytoplasmic diversity are maintained among hybrid parents. In this context, a continuous search for new CMS‐inducing cytoplasms is necessary. This paper reports detection of maternal inheritance of male sterility in the progeny derived from a natural hybrid between a wild relative [Cajanus lineatus (W. & A.) Maesen comb. nov.] of pigeonpea and an unknown pigeonpea [Cajanus cajan (L.) Millsp.] genotype. In the present study, the male sterility was maintained up to BC₇F₁ generation by an advanced breeding pigeonpea line ICPL 99044. This male sterility inducing cytoplasm of C. lineatus was tagged as A₆. In future, this CMS genetic stock can be used to develop a range of new pigeonpea hybrids with high yield and adaptation.     

Production of yellow-seeded Brassica napus through interspecific crosses

Yellow‐seeded Brassica napus was developed from interspecific crosses between yellow‐seeded Brassica rapa var.‘yellow sarson’ (AA), black‐seeded Brassica alboglabra (CC), yellow‐seeded Brassica carinata (Bbcc) and black‐seeded B. napus (AACC). Three different interspecific crossing approaches were undertaken. Approaches 1 and 2 were designed directly to develop yellow‐seeded B. napus while approach 3 was designed to produce a yellow‐seeded CC genome species. Approaches 1 and 2 differed in the steps taken after trigenomic interspecific hybrids (ABC) were generated from B. carinata×B. rapa crosses. The aim of approach 1 was to transfer the yellow seed colour genes from the A to the C genome as an intermediate step in developing yellow‐seeded B. napus. For this purpose, the ABC hybrids were crossed with black‐seeded B. napus and the three‐way interspecific hybrids were self‐pollinated for a number of generations. The F₇ generation resulted in the yellowish‐brown‐seeded B. napus line, No. 06. Crossing this line with the B. napus line No. 01, resynthesized from a black‐seeded B. alboglabra x B. rapa var.‘yellow sarson’ cross (containing the yellow seed colour genes in its AA genome), yielded yellow‐seeded B. napus. This result indicated that the yellow seed colour genes were transferred from the A to the C genome in the yellowish‐brown seed colour line No. 06. In approach 2, trigenomic diploids (AABBCC) were generated from the above‐mentioned trigenomic haploids (ABC). The seed colour of the trigenomic diploid was brown, in contrast to the yellow seed colour of the parental species. Trigenomic diploids were crossed with the resynthesized B. napus line No. 01 to eliminate the B genome chromosomes, and to develop yellow‐seeded B. napus with the AA genome of ‘yellow sarson’ and the CC genome of B. carinata with yellow seed colour genes. This interspecific cross failed to generate any yellow‐seeded B. napus. Approach 3 was to develop yellow‐seeded CC genome species from B. alboglabra×B. carinata crosses. It was possible to obtain a yellowish‐brown seeded B. alboglabra, but crossing this B. alboglabra with B. rapa var.‘yellow sarson’ failed to produce yellow seed in the resynthesized B. napus. The results of approaches 2 and 3 demonstrated that yellow‐seeded B. napus cannot be developed by combining the yellow seed colour genes of the CC genome of yellow‐seeded B. carinata and the AA genome of ‘yellow sarson’.     

Interspecific cross of Brassica oleracea var. alboglabra and B. napus : effects of growth condition and silique age on the efficiency of hybrid production, and inheritance of erucic acid in the self-pollinated backcross generation

Interspecific hybrids were produced from reciprocal crosses between Brassica napus (2n = 38, AACC) and B. oleracea var. alboglabra (2n = 18, CC) to introgress the zero-erucic acid alleles from B. napus into B. oleracea. The ovule culture embryo rescue technique was applied for production of F₁ plants. The effects of silique age, as measured by days after pollination (DAP), and growth condition (temperature) on the efficiency of this technique was investigated. The greatest numbers of hybrids per pollination were produced under 20°/15°C (day/night) at 16 DAP for B. oleracea (♀) × B. napus crosses, while under 15°/10°C at 14 DAP for B. napus (♀) × B. oleracea crosses. Application of the ovule culture technique also increased the efficiency of BC₁ (F₁ × B. oleracea) hybrid production by 10-fold over in vivo seed set. The segregation of erucic acid alleles in the self-pollinated backcross generation, i.e. in BC₁S₁ seeds, revealed that the gametes of the F₁ and BC₁ plants carrying a greater number of A-genome chromosomes were more viable. This resulted in a significantly greater number of intermediate and a smaller number of high-erucic acid BC₁S₁ seeds.     

Identification of Maintainer Genes in Brassica napus L. for the Male-Sterility-Inducing Cytoplasm of Diplotaxis muralis L.

Male fertility of F¹ interspecific hybrid plants derived from crosses between cytoplasmic male-sterile Brassica campestris in Diplotaxis muralis cytoplasm and 147 B. napus cultivars was Investigated. F¹, plants obtained, from crosses with the B. napus cultivars‘Mangum’and‘Hinchu’were male-sterile while F¹ plants derived from all other crosses were male-fertile. This indicated that these two cultivars carried maintainer genes far the male-sterility-inducing cytoplasm of D. muralis. Sterility was stable In plants derived from backcrosses of male-sterile F; plants with‘Mangun and‘Hinchu’but the seed set of backcross plants was low. With restorer genes readily available in B. napus, these findings could lead to the development of a new cytoplasmic male sterility system for the breeding of B. napus hybrid cultivars.     

Histological and inheritance studies of partial resistance in the Brassica napus–Albugo candida host-pathogen interaction

Traditional and doubled haploid (DH) genotypes of oilseed Brassica spp. resistant, partially resistant, moderately susceptible, and susceptible to Albugo candida were compared for phenotypic development of host‐pathogen interaction and histology of host‐pathogen interaction. The partially resistant genotype showed pinhead‐size pustules, mainly on the upper surface of cotyledonary leaves. Relatively less mycelium was observed in the partially resistant genotype compared with the susceptible genotype. In resistant B. napus genotypes, there was neither pustule development nor any mycelial growth. In the moderately susceptible genotype, the pustules were similar to those in the partially resistant genotype in being of pinhead‐size and occasionally coalescing. However, ample mycelial growth in the mesophyll tissue in the moderately susceptible genotype was similar to that in the susceptible control B. rapa cv. ‘Torch’. The susceptible genotype B. rapa cv. ‘Torch’ also showed large coalescing pustules. In the non‐host B. juncea cv. ‘Commercial Brown’, no pustules were formed although some mycelial growth was observed beneath the epidermal cell layer and in the mesophyll cell layer of the cotyledonary leaf tissue. For inheritance studies, two partially resistant B. napus genotypes were crossed with a resistant B. napus genotype. Various generations viz., F1, F1(reciprocal), F₂, and DHs produced from the crosses were inoculated with a zoospore suspension of race 7v of A. candida. The partially resistant phenotype appeared to be controlled by a single recessive gene designated as wpr with variable expression. The simple inheritance of partial resistance has implications for disease resistance breeding against white rust, as this type of resistance can be easily incorporated into elite breeding lines through conventional and DH breeding methods.     

Broadening the genetic base of <Emphasis Type="Italic">Brassica napus</Emphasis> canola by interspecific crosses with different variants of <Emphasis Type="Italic">B. oleracea</Emphasis>

Broadening the genetic base of the C genome of Brassica napus canola by use of B. oleracea is important. In this study, the prospect of developing B. napus canola lines from B. napus?×?B. oleracea var. alboglabra, botrytis, italica and capitata crosses and the effect of backcrossing the F₁’s to B. napus were investigated. The efficiency of the production of the F₁’s varied depending on the B. oleracea variant used in the cross. Fertility of the F₁ plants was low—produced, on average, about 0.7 F₂ seeds per self-pollination and similar number of BC₁ seeds on backcrossing to B. napus. The F₃ population showed greater fertility than the BC₁F₂; however, this difference diminished with the advancement of generation. The advanced generation populations, whether derived from F₂ or BC₁, showed similar fertility and produced similar size silique with similar number of seeds per silique. Progeny of all F₁’s and BC₁’s stabilized into B. napus, although B. oleracea plant was expected, especially in the progeny of F₁ (ACC) owing to elimination of the A chromosomes during meiosis. Segregation distortion for erucic acid alleles occurred in both F₂ and BC₁ resulting significantly fewer zero-erucic plants than expected; however, plants with?≤?15% erucic acid frequently yielded zero-erucic progeny. No consistent correlation between parent and progeny generation was found for seed glucosinolate content; however, selection for this trait was effective and B. napus canola lines were obtained from all crosses. Silique length showed positive correlation with seed set; the advanced generation populations, whether derived from F₂ or BC₁, were similar for these traits. SSR marker analysis showed that genetically diverse canola lines can be developed by using different variants of B. oleracea in B. napus?×?B. oleracea interspecific crosses.     

Intergeneric crosses for the transfer of resistance to the beet cyst nematode from Raphanus sativus to Brassica napus

Summary The possibilities to transfer important traits and in particular resistance to the beet cyst nematode (Heterodera schachtii, abbrev. BCN) from Raphanus sativus to Brassica napus were investigated. For these studies B. napus, R. sativus, the bridging hybrid ×Brassicoraphanus (Raparadish) as well as offspring of the cross ×Brassicoraphanus (Raparadish) ×B. napus were used. Reciprocal crosses between B. napus and R. sativus were unsuccessful, also with the use of embryo rescue. Crosses between ×Brassicoraphanus as female parent and B. napus resulted in a large number of F₁ hybrids, whereas the reciprocal cross yielded mainly matromorphic plants. BC₁, BC₂ and BC₃ plants were obtained from backcrosses with B. napus, which was used as the male parent. F₁ hybrids and BC plants showed a large variation for morphology and male and female fertility. Cuttings of some F₁ and BC₁ plants, obtained from crosses involving resistant plants of ×Brassicoraphanus, were found to possess a level of resistance similar to that of the resistant parent. These results and indications for meiotic pairing between chromosomes of genome R with those of the genomes A and/or C suggest that introgression of the BCN-resistance of Raphanus into B. napus may be achieved.     

Development of B-Genome Chromosome Addition Lines of B. napus Using Different Interspecific Brassica Hybrids

By interspecific hybridization within the genus Brassica, trigenomic haploids were produced and back-crossed four times with B. napus, variety ‘Andor’. From this material, monosomic B-genome chromosome addition lines were selected with the extra chromosome derived from three different B-genome sources, i.e., B. nigra (BB), B. carinata (BBCC), and B. juncea (AABB). After selfing and/or microspore culture, disomic addition lines were obtained. Meiotic behavior was studied of the trigenomic hybrids, the pentaploid BC₁ plants, and the monosomic addition lines. The addition lines were shown to possess cytological stability and good fertility.     

Inheritance and mapping of a restorer gene for the rapeseed cytoplasmic male sterile line 681A

A novel cytoplasmic male sterility‐fertility restoration system has been developed in rapeseed (Brassica napus). The cytoplasmic male sterile line 681A was derived from a spontaneous male sterile mutant in a newly released double‐low rapeseed cultivar ‘Xiangyou 13′. The restorer line 714R was identified in the interspecific progeny from a B. napus×B. juncea‐cross. Genetic analysis showed that fertility restoration for 681A cytoplasmic male sterility was controlled by a single dominant nuclear gene which might originate from B. juncea. The RAPD marker S1039_‐520 was found to be linked to the restorer gene in F₂ progeny of 681A × 714R with a recombination frequency of 5.45%.