Dataset Information

Improvement of Stable Restorer Lines for Blast Resistance through Functional Marker in Rice (Oryza sativa L.).

ABSTRACT: Two popular stable restorer lines, CB 87 R and CB 174 R, were improved for blast resistance through marker-assisted back-cross breeding (MABB). The hybrid rice development program in South India extensively depends on these two restorer lines. However, these restorer lines are highly susceptible to blast disease. To improve the restorer lines for resistance against blasts, we introgressed the broad-spectrum dominant gene Pi54 into these elite restorer lines through two independent crosses. Foreground selection for Pi54 was done by using gene-specific functional marker, Pi54 MAS, at each back-cross generation. Back-crossing was continued until BC3 and background analysis with seventy polymorphic SSRs covering all the twelve chromosomes to recover the maximum recurrent parent genome was done. At BC3F2, closely linked gene-specific/SSR markers, DRRM-RF3-10, DRCG-RF4-8, and RM 6100, were used for the identification of fertility restoration genes, Rf3 and Rf4, along with target gene (Pi54), respectively, in the segregating population. Subsequently, at BC3F3, plants, homozygous for the Pi54 and fertility restorer genes (Rf3 and Rf4), were evaluated for blast disease resistance under uniform blast nursery (UBN) and pollen fertility status. Stringent phenotypic selection resulted in the identification of nine near-isogenic lines in CB 87 R × B 95 and thirteen in CB 174 R × B 95 as the promising restorer lines possessing blast disease resistance along with restoration ability. The improved lines also showed significant improvement in agronomic traits compared to the recurrent parents. The improved restorer lines developed through the present study are now being utilized in our hybrid development program.

SUBMITTER: Ramalingam J

PROVIDER: S-EPMC7692511 | biostudies-literature | 2020 Oct

REPOSITORIES: biostudies-literature

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Improvement of Stable Restorer Lines for Blast Resistance through Functional Marker in Rice (<i>Oryza sativa</i> L.).

Ramalingam Jegadeesan J Palanisamy Savitha S Alagarasan Ganesh G Renganathan Vellaichamy Gandhimeyyan VG Ramanathan Ayyasamy A Saraswathi Ramasamy R

Genes 20201027 11

Two popular stable restorer lines, CB 87 R and CB 174 R, were improved for blast resistance through marker-assisted back-cross breeding (MABB). The hybrid rice development program in South India extensively depends on these two restorer lines. However, these restorer lines are highly susceptible to blast disease. To improve the restorer lines for resistance against blasts, we introgressed the broad-spectrum dominant gene <i>Pi54</i> into these elite restorer lines through two independent crosses ...[more]

PMID: 33121205

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Project description:Exploration of and understanding diversity and variability in genotypes of germplasm determines the success of rice improvement programs. One of the most important determinants of the success of breeding programs is genetic diversity and inheritance of traits. Genetic variability analysis helps breeders to determine the appropriate selection method and standards to be used to improve the preferred trait. The aim of this study was to estimate genetic components, heritability and to obtain information about genetic diversity using cluster analysis and principal component analysis. Twenty rice genotypes with three replicates in a randomized complete block design were analyzed at the Experimental Farm at Sakha Agricultural Research Station, Sakha, Kafr El-Sheikh, Egypt, during the period from 2017 to 2020. The results of the analysis of variance showed that highly significant variations were recorded between the studied genotypes for all traits. The genotypic coefficient of variation (GCV%) and phenotypic (PCV%) coefficient of variation were moderate for plant height, panicles/plant, panicle weight, spikelets/panicle, filled grains/panicle, grain yield/plant and amylose content percentage for the first-year, second-year and combined data. This indicates the existence of beneficial genetic variability that can be exploited to improve these traits. The broad-sense estimates of heritability were high and recorded values higher than 60% for all the studied traits for the two-year and combined data, except for hulling percentage. This indicates that the selection of traits that have high heritability and are less affected by the environment leads to an acceleration of the improvement of these traits. The results from the cluster analysis and principal component analysis revealed a high level of genotypic variation among the studied genotypes and genetic diversity between them. One of the most important outcomes of this study is the successful utilization of genetic resources (germplasm) from ancient varieties and lines of rice in selecting and identifying 17 new restoration lines of rice, which have various improvement purposes in rice and hybrid rice breeding programs.

Project description:Bacterial blight (BB), caused by Xanthomonas oryzae pv.oryzae is one among the major diseases in rice, which in severe condition cause losses up to 60% in total yield. Marker assisted pyramiding of three broad spectrum BB resistance genes (xa5, xa13, and Xa21) in prominent rice varieties is the most economical and effective strategy for the management of the BB disease. We report here the pyramiding of three genes (xa5, xa13, and Xa21) in maintainer lines (CO 2B, CO 23B, and CO 24B) of three promising wild abortive cytoplasmic male sterile lines (CO 2A, CO 23A, and CO 24A) through functional markers assisted back cross breeding. IRBB60 with xa5, xa13, and Xa21 genes is used as a donor parent. BC2F1 and BC2F2 generations from a cross of CO 2B, CO 23B, and CO 24B with IRBB60 were evaluated for bacterial blight and non-fertility restoration. In BC2F1, plants with all three resistance genes (xa5, xa13, and Xa21) and high parent genome recovery was identified. In BC2F2, plants with all resistance genes and without fertility restorer (Rf3 and Rf4) were selected. Based on agronomic traits, BB resistance and maintenance of sterility, two plants each in CO 2B × IRBB60, CO 24B × IRBB60 and one plant in CO 23B × IRBB60 combinations were identified. The identified lines were crossed with respective male sterile lines for conversion of improved B line into CMS line through back-crossing, in addition to selfing. The plants with high recurrent genome and phenotypically similar to parental lines and sterile are being used for the hybrid rice development program. Currently, using these lines (improved CMS line), test crosses were made to develop new rice hybrids. Hybrids combinations viz., CO 23A × AD08009R and CO 24A × IET20898R were found to be stable at different locations with high yield. The R line used in this study has been introgressed with xa5, xa13, and Xa21 genes in a separate breeding program. These new hybrids with resistance against bacterial blight will increase the crop production at BB environment.

Project description:Rice is one of the most important crops in Egypt. Due to the gap between the demand and the availability of the local edible oils, there is need to raise the nutritional value of rice and, therefore, to improve the nutritional value of the consumer. This research was carried out at the Experimental Farm of Sakha Agricultural Research Station, Sakha, Kafr El-Sheikh, Egypt, during the 2019 and 2020 seasons. Five newly developed genotypes of rice, namely NRL 63, NRL 64, NRL 65, NRL 66, and Giza 178 as check variety (control), were used to evaluate the analytical characterization of raw rice bran and rice bran oil from rice bran, study the genetic variability and genetic advance for various quantitative and qualitative traits in rice as well as, rice bran oil. The genotypes were evaluated in a randomized complete block design (RCBD) with three replications. Analysis of variance revealed highly significant variations among the genotypes for all the studied characters. Data revealed that high estimates of the phenotypic coefficient of variance (PCV%) and genotypic coefficient of variance (GCV%) were observed for amylose content percentage, peroxide value (meq/kg oil), myristic C14:0, and arachidic C20:0, indicating that they all interacted with the environment to some extent. The line NRL66 and NRL64 showed the highest and high values of mean performance for grain yield (t/h), grain type (shape), amylose content percentage, crude protein, ether extract and ash of milled rice, crude protein, ether extract, ash, phosphorus, magnesium, manganese, zinc, and iron of stabilized rice bran oil. Genetic advance as a percentage of mean was high for most of the studied traits. It indicates that most likely, the heritability is due to additive gene effects, and selection may be effective. The percentage of advantage over the Giza 178 as the commercial variety was significant and highly significant among the genotypes for all the characters studied in the two years, indicating that the selection is effective in the genetic improvements for these traits.

Dataset Information

Improvement of Stable Restorer Lines for Blast Resistance through Functional Marker in Rice (Oryza sativa L.).

Publications

Improvement of Stable Restorer Lines for Blast Resistance through Functional Marker in Rice (<i>Oryza sativa</i> L.).

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