Promising experimental hybrids of spring rapeseed (Brassica napus L.) for CMS-system of Polima type

One of the prior directions in spring rapeseed breeding is development of heterotic hybrids. Seed growing of the most hybrids F1 used in production are often carried out by two types of cytoplasmic male sterility, they are polima and ogura. At the Lipetsk Rapeseed Research Institute, fertility restorers on sterile cytoplasm were made and estimated for the main valuable traits. The purpose of the research was to develop effective restorers, which are necessary for obtaining of highly productive hybrids on the Polima type cytoplasmic male sterility (CMS). The object of research was 56 varieties of Brassica napus L., which were selected in 2013. It is noted that hybrids F1 were more productive than the parental forms and the standards (the varieties Ratnik and Rif). The restorer line LHR-1 is of practical interest for the development of hybrids on the Polima CMS.

Genetic Diversity and Population Structure of the Parental lines of Hybrid Japonica Rice in Northern China Revealed by 8K SNP-Chips

BackgroundThe hybrid rice varieties have made a significant contribution to food security. Although there has been rapid development of hybrid indica rice variety, the development of hybrid japonica rice has been relatively slow. This study aimed to understand the genetic background of representative parental lines of hybrid japonica rice in northern China that were beneficial for increasing efficiency to find a superior breeding combination using a restorer line and a sterile line. ResultsWe selected 137 parental lines of hybrid japonica rice, including 90 restorer lines, 47 sterile lines, which broadly represented the recent rice breeding trends in China. These lines were genotyped using 8K SNP-Chips (China Golden Marker Biotechnology Co. Ltd.) to understand the genetic diversity, population structure, phylogenetic evolution, and indica blood content. The genetic diversity of total parental lines averaged 0.264, with values for the restorer line and sterility line as 0.287 and 0.148, respectively. Based on the model-based population structure analysis and distance-based clustering, these 137 lines were divided into 14 groups, including seven independent restorer lines groups and seven mixture groups. There were 70% restorer lines in the above-mentioned seven independent restorer lines groups, and the indica blood content was 0.348, while 30% restorer lines were genetically similar to the sterile lines and constituted the other seven mixture groups, where the indica blood content in the restorer lines and the sterility lines was 0.142 and 0.121, respectively. The results of distance-based clustering revealed that the restorer lines, Group 1 and Group 2 (containing only restorer lines), had longer genetic distances with groups containing mainly sterile lines (the genetic distance ranged from 0.672 to 0.788), which served as a potential heterotic for hybrid rice breeding. This observation was consistent with the breeding strategy of high yield hybrid japonica rice.ConclusionsThe typical japonica sterile lines were crossed with the restorer lines containing high indica components indicating a strong heterosis pattern was a feasible scheme for heterosis utilization of indica-japonica subspecies. Thus, the effective ways to further improve the rice quality of hybrid japonica rice in northern China included maintaining moderate genetic distance and indica components between the parental lines along with the excellent quality of both the parental lines.

Physical mapping and InDel marker development for the restorer gene Rf2 in cytoplasmic male sterile CMS-D8 cotton

Background Cytoplasmic male sterile (CMS) with cytoplasm from Gossypium Trilobum (D8) fails to produce functional pollen. It is useful for commercial hybrid cotton seed production. The restore line of CMS-D8 containing Rf2 gene can restore the fertility of the corresponding sterile line. This study combined the whole genome resequencing bulked segregant analysis (BSA) with high-throughput SNP genotyping to accelerate the physical mapping of Rf2 locus in CMS-D8 cotton. Methods The fertility of backcross population ((sterile line×restorer line)×maintainer line) comprising of 1623 individuals was investigated in the field. The fertile pool (100 plants with fertile phenotypes, F-pool) and the sterile pool (100 plants with sterile phenotypes, S-pool) were constructed for BSA resequencing. The selection of 24 single nucleotide polymorphisms (SNP) through high-throughput genotyping and the development insertion and deletion (InDel) markers were conducted to narrow down the candidate interval. The pentapeptide repeat (PPR) family genes and upregulated genes in restore line in the candidate interval were analysed by qRT-PCR. Results The fertility investigation results showed that fertile and sterile separation ratio was consistent with 1:1. BSA resequencing technology, high-throughput SNP genotyping, and InDel markers were used to identify Rf2 locus on candidate interval of 1.48 Mb on chromosome D05. Furthermore, it was quantified in this experiment that InDel markers co-segregated with Rf2 enhanced the selection of the restorer line. The qRT-PCR analysis revealed PPR family gene Gh_D05G3391 located in candidate interval had significantly lower expression than sterile and maintainer lines. In addition, utilization of anther RNA-Seq data of CMS-D8 identified that the expression level of Gh_D05G3374 encoding NB-ARC domain-containing disease resistance protein in restorer lines was significantly higher than that in sterile and maintainer lines. Conclusions This study not only enabled us to precisely locate the restore gene Rf2 but also evaluated the utilization of InDel markers for marker assisted selection in the CMS-D8 Rf2 cotton breeding line. The results of this study provide an important foundation for further studies on the mapping and cloning of restorer genes.

Physical mapping and InDel marker development for the restorer gene Rf2 in cytoplasmic male sterile CMS-D8 cotton

Background: Cytoplasmic male sterile (CMS) with cytoplasm from Gossypium Trilobum (D8) fails to produce functional pollen. It is useful for commercial hybrid cotton seed production. The restore line of CMS-D8 containing Rf2 gene can restore the fertility of the corresponding sterile line. This study combined the whole genome resequencing bulked segregant analysis (BSA) with high-throughput SNP genotyping to accelerate the physical mapping of Rf2 locus in CMS-D8 cotton. Methods: The fertility of backcross population ((sterile line×restorer line)×maintainer line) comprising of 1623 individuals was investigated in the field. The fertile pool (100 plants with fertile phenotypes, F-pool) and the sterile pool (100 plants with sterile phenotypes, S-pool) were constructed for BSA resequencing. The selection of 24 single nucleotide polymorphisms (SNP) through high-throughput genotyping and the development insertion and deletion (InDel) markers were conducted to narrow down the candidate interval. The pentapeptide repeat (PPR) family genes and upregulated genes in restore line in the candidate interval were analysed by qRT-PCR. Results: The fertility investigation results showed that fertile and sterile separation ratio was consistent with 1:1. BSA resequencing technology, high-throughput SNP genotyping, and InDel markers were used to identify Rf2 locus on candidate interval of 1.48 Mb on Chromosome D05. Furthermore, it was quantified in this experiment that InDel markers co-segregated with Rf2 enhanced the selection of the restorer line. The qRT-PCR analysis revealed PPR family gene Gh_D05G3391 located in candidate interval had significantly lower expression than sterile and maintainer lines. In addition, utilization of anther RNA-Seq data of CMS-D8 identified that the expression level of Gh_D05G3374 encoding NB-ARC domain-containing disease resistance protein in restorer lines was significantly higher than that in sterile and maintainer lines. Conclusions: This study not only enabled us to precisely locate the restore gene Rf2 but also evaluated the utilization of InDel markers for marker assisted selection in the CMS-D8 Rf2 cotton breeding line. The results of this study provide an important foundation for further studies on the mapping and cloning of restorer genes.

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.

Physical mapping and InDel marker development for the restorer gene Rf2 in cytoplasmic male sterile CMS-D8 cotton

Background: Cytoplasmic male sterile (CMS) with cytoplasm from Gossypium Trilobum (D8) fails to produce functional pollen. It is useful for commercial hybrid cotton seed production. The restore line of CMS-D8 containing Rf 2 gene can restore the fertility of the corresponding sterile line. This study combined the whole genome resequencing bulked segregant analysis (BSA) with high-throughput SNP genotyping to accelerate the physical mapping of Rf 2 locus in CMS-D8 cotton. Methods: The fertility of backcross population ((sterile line×restorer line)×maintainer line) comprising of 1623 individuals was investigated in the field. The fertile pool (100 plants with fertile phenotypes, F-pool) and the sterile pool (100 plants with sterile phenotypes, S-pool) were constructed for BSA resequencing. The selection of 24 single nucleotide polymorphisms (SNP) through high-throughput genotyping and the development insertion and deletion (InDel) markers were conducted to narrow down the candidate interval. The pentapeptide repeat (PPR) family genes and upregulated genes in restore line in the candidate interval were analysed by qRT-PCR. Results: The fertility investigation results showed that fertile and sterile separation ratio was consistent with 1:1. BSA resequencing technology, high-throughput SNP genotyping, and InDel markers were used to identify Rf 2 locus on candidate interval of 1.48 Mb on Chromosome D05. Furthermore, it was quantified in this experiment that InDel markers co-segregated with Rf 2 enhanced the selection of the restorer line. The qRT-PCR analysis revealed PPR family gene Gh_D05G3391 located in candidate interval had significantly lower expression than sterile and maintainer lines. In addition, utilization of anther RNA-Seq data of CMS-D8 identified that the expression level of Gh_D05G3374 encoding NB-ARC domain-containing disease resistance protein in restorer lines was significantly higher than that in sterile and maintainer lines. Conclusions: This study not only enabled us to precisely locate the restore gene Rf 2 but also evaluated the utilization of InDel markers for marker assisted selection in the CMS-D8 Rf 2 cotton breeding line. The results of this study provide an important foundation for further studies on the mapping and cloning of restorer genes.