Testcross Progeny Research Articles

Character Association Study in Maize Hybrids Developed through Integration of Rapid Cycle Genomic Selection and Doubled Haploid Technology for Heat Stress Tolerance

Heat stress is becoming a major constraint for maize production; therefore heat stress resilience has emerged as an important aspect in maize hybrids targeted for post rainy spring season. Selection of genotypes based on high grain yield under heat stress condition is often misleading and the identification of secondary traits also associated with grain yield may help in development of heat tolerant cultivars. Hence, the present research work to study the association of traits was conducted during summer and kharif 2018 and rabi 2018-19 at Bheemarayanagudi and Raichur using 111 testcross progenies of doubled haploids derived from C1, C2 and C3 cycles of multi-parental synthetic population 1 and 2 improved through rapid cycle genomic selection for heat stress tolerance. The phenotypic correlation analysis under heat stress and optimal conditions, number of kernels per cob and cob girth exhibited the strong positive association with grain yield per plant. Further, under early spring condition number of kernels per cob, cob length, cob girth and 100 grain weight recorded the strong positive association with grain yield per plant. However, when considering across heat stress, early spring and optimal conditions, the grain yield per plant showed positive and significant strong to moderate association with the traits viz., number of kernels per cob, cob length and cob girth under all the seasons. In addition, days to 50% silking showed significant negative correlation with grain yield per plant under heat stress and optimal condition. Hence, the simultaneous selection criteria for the genotypes that exerts early silking, higher number of kernels per cob, higher cob girth and lengthy cob should be the priority of breeders to achieve higher grain yields in maize under heat stress condition as well as optimal conditions.

Cytoplasmic Male Sterility Incidence in Potato Breeding Populations with Late Blight Resistance and Identification of Breeding Lines with a Potential Fertility Restorer Mechanism.

Cytoplasmic male sterility (CMS) in potato is a common reproductive issue in late blight breeding programs since resistant sources usually have a wild cytoplasmic background (W or D). Nevertheless, in each breeding cycle male fertile lines have been observed within D- and T-type cytoplasms, indicating the presence of a fertility restorer (Rf) mechanism. Identifying sources of Rf and complete male sterility to implement a CMS-Rf system in potato is important since hybrid breeding is a feasible breeding strategy for potato. The objective of this study was to identify male fertile breeding lines and potential Rf candidate lines in the CIP late blight breeding pipeline. We characterized male fertility/sterility-related traits on 142 breeding lines of known cytoplasmic type. We found that pollen viability is not a reliable estimate of male sterility in diverse backgrounds. Breeding lines of the T-type cytoplasmic group had higher levels of male fertility than breeding lines of the D-type cytoplasmic group. With the help of pedigree records, reproductive traits evaluations and test crosses with female clones of diverse background, we identified four male parental lines segregating for Rf and three female parental lines that generated 100% male sterile progeny. These identified lines and generated test cross progenies will be valuable to develop validation populations for mitochondrial or nuclear markers for the CMS trait and for dihaploid generation of Rf+ lines that can be later employed in diploid hybrid breeding.

Restoration ability of newly developed restorer gene pool inbreds on two different CMS sources in sunflower (Helianthus annuus L.)

Classical cytoplasmic male sterility (PET-1) discovered by Leclercq and a few restorer lines are being utilized for commercial hybrid seed production in sunflowers over the world since 1972. The utilisation of a single source of male sterility results in a high level of vulnerability to biotic and abiotic stresses. The goal of this study was to identify new fertility restorers for two different cytoplasmic male sterile sources, i.e., PET-1 (COSF-6A, COSF-7A, CMS-38A, ARM-248A) and CMS PEF (FMS-852A). Five CMS lines were crossed with newly developed drought tolerant 10 inbred lines in Line x Tester fashion and an evaluation of test cross progenies was conducted. All the inbreds were categorized into complete, partial restorers and maintainers through cytological observation. Six inbreds, viz., RGP-157, RGP-184, RGP-190, RGP-223, RGP-225 and RGP-233 behaved as restorers for all the CMS lines and restored fertility, while RGP-222 and 298R inbreds maintained sterility. The CMS line, FMS-852A was maintained by four inbreds indicating the involvement of different gene(s), while six inbreds, RGP-157, RGP-184, RGP-190, RGP-223, RGP-225 and RGP-233 were restored its fertility. None of the inbreds behaved as partial restorers for any of the CMS lines. The fertility restoration ranged from 91.4 to 97.4 per cent in different cross combinations. In the present study, pollen fertility of up to 80 per cent was observed for the PET-1 source. However, only 60 per cent of the pollen fertility was observed for CMS fallax. From the study, it was evident that among the two CMS sources, restorers for PET-1 and PEF were available. Efforts should be made to utilize CMS PEF for the production of more productive sunflower hybrids resistant to biotic and abiotic stresses. Keywords: CMS sources, Inbreds, Maintainer, Restorer, Sunflower

DNA Marker Assisted Identification of Promising Exotic Lines as Pollen Fertility Restorers and Validation Based on Restorer Related Traits Chilli (Capsicum Annuum L.) Test Cross Progenies

DNA Marker Assisted Identification of Promising Exotic Lines as Pollen Fertility Restorers and Validation Based on Restorer Related Traits Chilli (Capsicum Annuum L.) Test Cross Progenies

Genetic architecture, physio-biochemical characterization and identification of elite cytoplasmic male sterile (pt-CMS) based combiners in developing antioxidant-rich carrot

AbstractExistence of genetic divergence, appropriate characterization of breeding lines for economically important traits and determining parents with favourable alleles is the crux of crop genetic improvement programmes. This study is the first report of unravelling genetics and potential of petaloid-type cytoplasmic male sterile (pt-CMS) lines in carrot. Ten pt-CMS lines were crossed with 10 inbreds in line × tester mating fashion to generate 100 testcross progenies. Nutritional profiling of the 100 testcrosses progenies along with 20 parental types was carried out for two consecutive years for eight important traits to identify superior combiners. The pooled analysis revealed that the carotenoid content in root is under the genetic control of major genes (oligogenic). The pooled analysis revealed less than unity value of σ2A/D and σgca2/σsca2 for majority of the traits depicting preponderance of non-additive gene effects. The pt-CMS lines KT-28A, Kt-62A, KT-80A and KT-95A were identified as good combiners for carotenoids. The cross combination, KT-98A × KS-50 identified as the best heterotic combiner for CUPRAC and FRAP content over the years. Similarly, the combinations, KT-62A × KS-21, KT-80A × New Kuroda and KT-62A × KS-59 were found promising across the years for developing nutritionally rich F1 hybrids. The interaction analysis among the different antioxidant traits and plant pigments unveiled the scope of simultaneous improvement.

Estimation of epistasis and genetic components of variance for different traits in cucumber (Cucumis sativus)

To estimate epistasis and components of genetic variance a study was carried out during 2016 and 2017 at Experimental Research Farm of Department of Vegetable Science, Dr YSP UH & F Nauni, Solan, (HP) and data were recorded for different qualitative and quantitative traits using triple test cross (TTC) analysis of an inter-varietal cross LC-1-1 × K-75 of cucumber (Cucumis sativus L.). Three testers of cucumber named LC-1-1, K-75 and their F1 (LC-1-1 × K-75) were crossed to 15 inbred lines for detecting the additive, dominance and epistatic components of genetic variance. Good quantum of genetic variability has been generated through triple test cross progenies with respect to different traits studied as revealed by the significant analysis of variance. TTC analysis revealed that overall epistasis and j+l type component were found to be significant for majority of the traits except fruit breadth and total soluble solids. Further, experimental results showed that (i) type of epistasis were also significant for majority of the traits under study. The components of genetic variance were estimated using analysis of variance for sums and differences revealed the importance of both additive (D) as well as dominance (H) components of genetic variance in controlling various traits and showed partial dominance except over dominance for fruit breadth and severity of downy mildew. Therefore, kind of genetic variance revealed from triple test cross can be exploited by intermating selected individuals in early segregating generations with delayed selection in later generations, or recurrent selection followed by pedigree method to exploit both additive and non-additive components along with epistasis in cucumber.

Genetic gains with genomic versus phenotypic selection for drought and waterlogging tolerance in tropical maize (Zea mays L.)

Erratic rainfall often results in intermittent drought and/or waterlogging and limits maize (Zea mays L.) productivity in many parts of the Asian tropics. Developing climate-resilient maize germplasm possessing tolerance to these key abiotic stresses without a yield penalty under optimal growing conditions is a challenge for breeders working in stress-vulnerable agro-ecologies in the region. Breeding stress-resilient maize for rainfed stress-prone ecologies is identified as one of the priority areas for CIMMYT-Asia maize program. We applied rapid cycle genomic selection (RCGS) on two multiparent yellow synthetic populations (MYS-1 and MYS-2) to improve grain yield simultaneously under drought and waterlogging conditions using genomic-estimated breeding values (GEBVs). Also, the populations were simultaneously advanced using recurrent phenotypic selection (PS) by exposing them to managed drought and waterlogging and intermating tolerant plants from the two selection environments. Selection cycles per se (C1, C2, and C3) of the two populations developed using RCGS and PS approach and their test-cross progenies were evaluated separately in multilocation trials under managed drought, waterlogging, and optimal moisture conditions. Significant genetic gains were observed with both GS and PS, except with PS in MYS-2 under drought and with GS in MYS-1 under waterlogging. Realized genetic gains from GS were relatively higher under drought conditions (110 and 135 kg ha−1 year−1) compared to waterlogging (38 and 113 kg ha−1 year−1) in both MYS-1 and MYS-2, respectively. However, under waterlogging stress PS showed at par or better than GS as gain per year with PS was 80 and 90 kg ha−1, whereas with GS it was 90 and 43 kg ha−1 for MYS-1 and MYS-2, respectively. Our findings suggested that careful constitution of a multiparent population by involving trait donors for targeted stresses, along with elite high-yielding parents from diverse genetic background, and its improvement using RCGS is an effective breeding approach to build multiple stress tolerance without compromising yield when tested under optimal conditions

Production of Restorer Lines from Segregating Progenies of Brassica napus L. Having Good Agronomic Value

Forty four testcross progenies obtained from crossing between five CMS and forty one candidate lines were evaluated both in field and laboratory condition to identify candidate restorer line(s). Nineteen testcross progenies were recorded as fully fertile with 100% plant fertility by counting the number of fertile plants from the total number of plants per lines. On the other hand from pollen fertility test, 11 testcross progenies [206A × 001(6), 9905A × 030(2), 9905A × 027(6) (0.57), 206A × 37(1) (0.68), 9904A × 027(4) (0.83), 248A × 020(6) (1.08), 248A × 018 (1.12), 248A × 022 (1.13), 248A × 017 (1.58), 248A × 038(2) (1.96) and 248A × 001(6) (2.02)] were found with 0-2.02% pollen sterility that could be mentioned as fertile or restorer lines for making hybrids. Agronomic performances were also satisfactory for these selected test cross progenies. The genotype 248A × 017 took the shortest time (30.00) for first flowering as well as ripening followed by 248A × 007(1). The highest number of pods per plant was observed in the testcross progeny 248A × 022 (649.59) and the highest number of seeds per pod (30.33) in 248A × 020(6). For seed weight per plant, 206A × 001(6) was recorded with maximum value (0.08g) while the lowest (23.33) number of seeds per plant was found in this progeny. In case of seed yield per plant, 248A × 022 gave the highest yield (30.30). The seed yield of the progenies 248A × 017 (23.49), 9905A × 027(6) (20.39), 248A × 001(6) (17.26), 9904A × 027(4) (17.02) and 248A × 038(2) (16.53) were also in the highest level.

Inheritance of plumage colour in the F1 and test cross progeny of Japanese quail

Recessive genes produced its phenotypic effect only when its allele is identical while the dominant ones produced its effect either with identical or dissimilar alleles. This study was conducted to determine the mode of inheritance of plumage colour in Japanese quail flock in Nigeria, using the Manchurian Gold (MG), Pharaoh (PH) and Panda White (PW) plumage types. All possible crosses were made among the three colour variants making a total of nine mating groups. A total number of 2,348 F1 chicks and 1,563 test cross progeny obtained from the incubated eggs were classified and counted by their down colour into observable plumage colour groups. The expected phenotypic ratios of the F1 and test cross progeny were computed based on the assumption that parents that were homozygous for a particular plumage colour breed true. The results revealed that the Pharaoh plumage quails carry the wild-type allele (Wb) in homozygous form or in heterozygous with the Panda White (wb) allele. The Manchurian gold plumage quails carry the Manchurian Gold-type allele (Wb+) in heterozygous with either Wb or wb. All the Panda White chicks were homozygous for the wb allele, which was recessive to both Wb and Wb+ alleles. The Chi-square results confirm the heterozygousity of the dominant phenotype in the test crosses. It can be concluded that inheritance of plumage colour is controlled by autosomal genes with dominant hierarchy of MG> PH> PW (Wb+ >Wb>wb).

Detection of Epistasis for Biometrical Traits in Urdbean [Vigna mungo (L.) Hepper] under Mid-hill Conditions of Northwestern Himalayas

Background: Pulses are rich in their nutritional values, but having lower yield as compared to cereals. For increasing yield parameters, various crop improvement programmes were used, which mainly depends on the genetic architecture of the crop and the type of gene action helps in deciding the breeding strategies. Keeping under consideration, the present study therefore, is important.Methods: Eighty one triple test cross progenies developed by crossing 27 lines with three testers viz., HPBU-111, Him Mash-1 and their F1s cross between (HPBU-111 x Him Mash-1). F1 seeds were produced by cross between HPBU-111 x Him Mash-1 during Kharif 2015. By crossing these three testers with 27 lines (females), 81 hybrids were developed during Kharif 2016. The eighty one F1 hybrids along with 27 lines and 3 testers were sown during Kharif 2017 in a randomized block design with three replications.Result: Epistasis was found to be an integral part of genetic variations for the traits viz., days to 50% flowering, days to 75% maturity, plant height (cm), number of branches per plant, pod length (cm), number of pods per plant, number of seeds per pod, seed yield per plant (g), biological yield per plant (g), 100 seed weight, harvest index (%) and protein content (%). i type epistatic interactions (additive x additive) had significant effects for all the traits except, plant height (cm), pod length (cm), number of seeds per pod and protein content (%). In addition to i (additive x additive), j+l (additive x dominance + dominance x dominance) type epistatic interactions was observed for all of the traits. Both additive and non-additive gene actions are important for most of the traits studied hence, simple selection procedures in the immediate progenies will not be so effective for achieving improvement in these traits.

Determining genetic combining ability, heterotic potential and gene action for yield contributing traits and Yellow Vein Mosaic Virus (YVMV) resistance in Okra (Abelmoschus esculentus(L.) Monech.)

AbstractBreeding for resistance to biotic stress and higher yield is a continuous process. Thus, the identification of desirable parents with good combining ability and nature of gene action for the target trait is of utmost importance. Hence, in this present investigation, 10 lines and three testers of Okra were crossed in line × tester mating design to generate 30 testcross progenies and their evaluation along with parents and check in a randomized complete block design with three replications. To depict the true picture of genetic variation among the parental genotypes, molecular diversity analysis was also carried out using genomic-simple sequence repeats before crossing to ascertain that sufficient variability is present among the parents. The molecular analysis grouped the parental genotypes into four clusters (I–IV). The analysis of variance revealed that all the treatments were significant for most of the traits. The combining ability analysis suggested Pusa A-4 as the best general combiner for earliness, Pusa Bhindi-5 for high yield, and DOV-92 for fruit length, plant height, yield per plant, and coefficient of infection for Yellow Vein Mosaic Virus Disease resistance. Similarly, the specific combining ability analysis suggested that the cross combinations DOV-92 × Pusa Bhindi-5 followed by DOV-92 × Pusa A-4 and DOV-92 × Pusa Sawani exhibit high economic heterosis for yield per plant as well as for disease resistance. Finally, estimation of the degree of dominance and predictability ratio was also worked out which indicated the prevalence of non-additive gene action for most of the traits pointing towards sufficient scope for heterosis breeding in Okra.

Genome‐wide quantitative trait loci detection for biofuel traits in switchgrass (Panicum virgatum L.)

AbstractSwitchgrass (Panicum virgatum L.) has been identified as a potential feedstock for cellulosic ethanol production in United States for its high biomass yield and adaptation to marginal lands. Composition of the cell wall plays an important role in bioethanol conversion. A total of 209 pseudo‐F1 testcross progenies obtained from a biparental cross, AP13 × VS16, were grown at three locations from 2008 to 2011. Near‐infrared spectroscopy was used to estimate cell wall composition from biomass harvested at maturity. A linkage map of the pseudo‐F1 testcross was constructed with 8,757 SNPs developed by genotyping‐by‐sequencing. Quantitative trait loci (QTL) analysis was performed on eight lignocellulosic traits, namely, klason lignin, sugar, glucose, xylose, hexose, ethanol, hexosoic ethanol, and cell wall ethanol conversion percentage. A total of 327 QTL were recorded for the eight lignocellulosic traits. We have identified 111 major regions in the switchgrass genome that underlie these lignocellulosic traits. Scanning of the genome sequence for genes flanking the QTL peaks, we identified 45 important genes that are involved in lignin biosynthesis, carbohydrate and sugar metabolism, and other biological and cellular functions. Identification of valuable genes associated with QTL along with pleotropic effects of the significant number of QTL suggests that simultaneous selection and genetic improvement of these traits are possible using marker‐assisted selection.

Is canopy temperature suitable for high throughput field phenotyping of drought resistance of winter rye in temperate climate?

Abstract The present study investigated genotypic differences in canopy temperature of 218 testcross progenies of a recombinant inbred lines mapping population of winter rye. For this purpose, we repeatedly measured canopy temperature (Tc) and air temperature (Ta) differences (Tc − Ta) in field trials on two locations with sandy soils in northern Germany, two water treatments (rainfed and irrigated) in two experimental years. The experimental conditions therefore covered a wide range of drought stress conditions between stem elongation and ripening under a high variation of environmental boundary conditions. Genotype effects on (Tc − Ta) were significant in both water treatments and were correlated to grain yield reduction under drought stress. With the chosen statistical model, we were able to account for moderate time-series effects and short-term fluctuations caused by changing boundary condition during single screens of (Tc − Ta). We could show that under certain weather conditions (Tc − Ta) can detect differences in drought stress tolerance more accurate than grain yield determination of rye.

Genetic Dissection of Nitrogen Use Efficiency in Tropical Maize Through Genome-Wide Association and Genomic Prediction.

In sub-Saharan Africa, one of the major challenges to smallholder farmers is soil with low fertility and inability to apply nitrogen fertilizer externally due to the cost. Development of maize hybrids, which perform better in nitrogen depleted soils, is one of the promising solutions. However, breeding maize for nitrogen use efficiency (NUE) is hindered by expensive phenotypic evaluations and trait complexity under low N stress. Genome-wide association study (GWAS) and genomic prediction (GP) are promising tools to circumvent this interference. Here, we evaluated a mapping panel in diverse environments both under optimum and low N management. The objective of this study was to identify SNPs significantly associated with grain yield (GY) and other traits through GWAS and assess the potential of GP under low N and optimum conditions. Testcross progenies of 411 inbred lines were planted under optimum and low N conditions in several locations in Africa and Latin America. In all locations, low N fields were previously depleted over several seasons, and no N fertilizer was applied throughout the growing season. All inbred lines were genotyped with genotyping by sequencing. Genotypic and GxE interaction variances were significant, and heritability estimates were moderate to high for all traits under both optimum and low N conditions. Genome-wide LD decay at r2 = 0.2 and r2 = 0.34 were 0.24 and 0.19 Mbp, respectively. Chromosome-specific LD decays ranged from 0.13 to 0.34 Mbps with an average of 0.22 Mbp at r2 = 0.2. GWAS analyses revealed 38 and 45 significant SNPs under optimum and low N conditions, respectively. Out of these 83 significant SNPs, 3 SNPs on chromosomes 1, 2, and 6 were associated either with different traits or the same trait under different management conditions, suggesting pleiotropic effects of genes. A total of 136 putative candidate genes were associated with the significant SNPs, of which seven SNPs were linked with four known genes. Prediction accuracies were moderate to high for all traits under both optimum and low N conditions. These results can be used as useful resources for further applications to develop hybrids or lines with better performance under low N conditions.

Variable Penetrance among Different Sources of the Male Fertility Restoration Allele of Onion

Hybrid onion (Allium cepa) seed is produced using cytoplasmic male sterility (CMS). For the most commonly used source of onion CMS, male fertile plants possess male sterile (S) cytoplasm and dominant allele(s) at one nuclear male fertility locus (Ms). Because male fertility restoration is not necessary for bulb production, it is desirable to purge dominant alleles at Ms from populations and breeding lines to facilitate the development of male sterile inbreds for hybrid production. In this research, we used molecular markers to establish the cytoplasms and genotypes at Ms in progenies from testcrosses of male sterile lines with plants from three populations [B2354, Ailsa Craig (AC), and Sapporo-Ki (Ski)] possessing the dominant Ms allele. We scored male fertility of testcross progenies by visual examination of flowers and acetocarmine staining of pollen. Different sources of the dominant Ms allele showed significantly different amounts of male fertility restoration and proportions of stainable pollen, complicating visual selection against the dominant Ms allele. For AC and Ski, molecular markers correctly predicted male sterility vs. male fertility of progenies in the greenhouse and field. However, for B2354, male fertility restoration was less clear and especially difficult to score under field conditions, consistent with reduced penetrance of male fertility restoration for this source of the dominant Ms allele. These results will be of interest to onion breeders selecting S-cytoplasmic male sterile lines for hybrid onion development.

Path Coefficient Analysis, Character Association and Variability Studies in Selected Maize (Zea mays L.) Genotypes Grown in Southern Nigeria

The success of any selection process is greatly enhanced by using appropriate selection indices. The knowledge of the relationship among various traits affecting grain yield is imperative to arrive at potentially effective selection index. The study was carried out to unveil the different attributes of genetic variability, the type of interrelationships among the various traits affecting yield. Fifteen local and improved maize inbred lines were crossed to three tester varieties to develop 45 test cross progenies. The parents and crosses (63 entries in all) were evaluated in two different locations with three replications at each location using the Randomized complete block design (RCBD). Data generated was recorded for the quantitative traits evaluated and subjected to statistical analysis for estimation of various variability parameters namely GCV, PCV, heritability and genetic advance alongside computing genotypic correlation coefficients and path coefficient analysis to unveil the direct and indirect effects of the various traits studied. The analysis of variability parameters evaluated revealed the presence of significant variability for all the traits studied. Grain yield, ear length, ear height, 100-seed weight and ear diameter showed high GCV estimates, with high heritability. The genetic advance was higher for plant height, ear length, grain/row and grain yield. The genotypic correlation coefficient revealed that ear diameter, 100 seed weight, ear length, kernel rows/ear and grains/row had highest significant correlation with grain yield. The path coefficient analysis revealed that highest direct effect on grain yield was exhibited by 100 seed weight followed by grains/row, kernel rows/ear, ear length and ear diameter. Most of the traits exerted their positive indirect effects through 100 – seed weight, kernel rows/ear and grains/row. The inferences of the results of the present study and their possible implications in maize breeding have been revealed.

Unique fertility restoration suppressor genes for male-sterile CMS ANN2 and CMS ANN3 cytoplasms in sunflower (Helianthus annuus L.)

Single dominant fertility restoration (Rf) genes for cytoplasmic male-sterile (CMS) sunflower lines CMS ANN2 and CMS ANN3 were previously identified in three and five sources, respectively. However, expressions of the dominant Rf genes were suppressed when crossing restoration lines with three inbred lines. Preliminary results indicated that segregation of fertility in most testcross progeny families from crosses of half-diallel F1’s of restoration lines with the two CMS lines, respectively, did not agree with those of the F2 generation of the half-diallel crosses. In this study, using selected CMS ANN2 and CMS ANN3 plants without the silencing suppressor (S) genes, we confirmed the existence of S genes in the nuclear genomes of the CMS lines used for crossing of the two CMS cytoplasms. Inheritance study suggested that Rf gene suppression was controlled by a single dominant gene in specific backgrounds, whereas two to three complementary S genes could exist in certain backgrounds. Using testcross population Rf ANN2-P21/RHA 274//Rf ANN2-P21, a single S gene from RHA 274, designated S1, was mapped to a recombination suppressed region on the sunflower linkage group (LG) 3, co-segregating with 16 SSR or single nucleotide polymorphism (SNP) markers, flanked by NSA_003339 and ORS124 at a distance of 1.4 and 0.7 cM, respectively. These molecular markers will potentially assist in identifying lines without suppressor genes, including CMS lines. Unique suppression of Rf genes confirmed existence of suppressor (S1) gene in CMS lines that mapped to a recombination suppressed region on linkage group 3, which will enhance understanding of cytoplasm-nuclear interactions.

Development of cytoplasmic male sterile lines in chilli (Capsicum annuum L.) and their evaluation across multiple environments.

A breeding program was initiated in 2009 to develop temperature stable CMS lines in chilli. ‘CCA 4261’ was used as a CMS donor. From the 11 testcross progeny screened, maintainer plants were identified from ‘SL 461’, ‘SL 462’ and ‘SD 463’. After 6 backcrosses to the maintainer plants, 17 CMS lines in diverse genetic backgrounds were established. The CMS lines were evaluated for stability of sterility over four environments during 2014–15 and 2015–16. The environments E1 and E3 represented the low temperature regime, and E2 and E4 the high temperature regime. The mean square values due to the genotypes and the environments were significant at p = 0.01 for pollen sterility (%), pollen release score, fruit setting (%) and number of seed fruit−1. The G × E interaction effects were significant for pollen sterility (%), fruit setting and number of seed fruit−1 and non-significant for pollen release score. Ten lines namely ‘CMS4611A’, ‘CMS4614A’, ‘CMS4622A’, ‘CMS4624A’, ‘CMS4626A’, ‘CMS46213A’, ‘CMS463D2A’, ‘CMS463D13A’, ‘CMS463D14A’ and ‘CMS463L5A’ were completely male sterile across the environments. Under open pollination conditions, the fruit and the seed setting ability of these lines was normal. The CMS transferred into the diverse genetic backgrounds would broaden the CMS germplasm resources in chilli.

Evaluation of new inbreds for fertility restoring and maintaining behaviours in two diverse CMS sources of sunflower (Helianthus annuus L.)

Eight cytoplasmic male sterile (CMS) lines of sunflower (Helianthus annuus L.) belonging to two different sources of cytoplasmic male sterility, PET-1 (H. petiolaris) (CMS-852A, CMS-7-1A, CMS-234A, CMS-2A, COSF-1A, COSF-7A and CMS-10A) and CMS I (H. lenticularis) (IMS-852A) were crossed with newly developed 20 inbred lines to identify the maintainer or restorer behaviour in Line x Tester fashion and evaluation of test cross progenies was conducted. The presence or absence of pollen in F1 s was recorded in the field whereas pollen fertility was confirmed in the laboratory by acetocarmine staining test. All the inbredswere categorized into complete, partial restorer and maintainer through cytological observation. Twelve inbreds viz., RHAGKVK-1, RHAGKVK-2, AKSFI-49-3, AKSFI-49-4, AKSFI-46-2, HOHAL-37,CSFI-5134,CSFI-5055, CSFI-5133, CSFI-5185, CSFI-5075and Selection-I restored the fertility for most of the PET-1 CMS lines, while CSFI-5033, IB0-50, IB-60, IB-61, IB-67 and IB-101 inbreds maintained sterility. The second CMS line IMS-852A, was maintained by 13 inbreds indicating involvement of different gene(s), while one inbred CSFI-5134 was restored its fertility. Some of the inbreds (AKSFI-49-3 and AKSFI-49-4) were behaved as partial restorers for CMS-10A. The range of fertility restoration in different cross combinations was between 46.6 and 99.5 per cent. In the present study 50 to 65 per cent frequency of pollen fertility was reported for PET-1. However, only 5 per cent frequency of pollen fertility was observed for CMS I. From the study it was evident that among the two CMS sources, restorers for CMS I are rather scarce. Efforts should be made to locate restorers for CMS I for its utilization in production of more productive sunflower hybrids

Substituting nuclear genome of Brassica juncea (L.) Czern & Coss. In cytoplasmic background of Brassica fruticulosa results in cytoplasmic male sterility

Backcross substitution of Brassica juncea (2n = 36; AABB) nucleus into the cytoplasm of a wild crucifer, Brassica fruticulosa helped in development of a new cytoplasmic male sterility (CMS) system. Male sterility was complete, stable, and expressed as rudimentary anthers containing sterile pollen grains. There was no impact on other floral as well as vegetative characters. All the natural B. juncea genotypes evaluated maintained the sterility. Gene for fertility restoration could be successfully introgressed from cytoplasm donor species. Genomic in situ hybridization studies revealed B. fruticulosa intogression in at least three chromosomes of the recipient species. Genetic studies carried out on F1, F2 and test cross progenies derived from hybridizing cytoplasmic male sterile and fertility restoring genotypes revealed a monogenic dominant control for the fertility restoration. Bulked segregant analysis with 588 SSR and 30 ISSR primers allowed identification of putative primers associated with fertility restoration. Co-segregation analysis of ten such primers with Rff gene revealed that Rf was flanked by two markers, namely cnu_m316 and nia_ m22, which were located 27.1 (LOD = 3.0) and 19.7 cM (LOD = 3.0) respectively around the gene in question. Distinctness of new CMS system from the ogura CMS was also demonstrated. This newly developed CMS-fertility-restorer system has a significant potential for hybrid seed production programs in mustard as an alternative to currently popular ogura CMS system.