Oryza minuta J. S. Presl ex C. B. Presl is a tetraploid wild rice with resistance to several insects and diseases, including blast (caused by Pyricularia grisea) and bacterial blight (caused by Xanthomonas oryzae pv. oryzae). To transfer resistance from the wild species into the genome of cultivated rice (Oryza sativa L.), backcross progeny (BC1, BC2, and BC3) were produced from interspecific hybrids of O. sativa cv 'IR31917-45-3-2' (2n=24, AA genome) and O. minuta Acc. 101141 (2n=48, BBCC genomes) by backcrossing to the O. sativa parent followed by embryo rescue. The chromosome numbers ranged from 44 to 47 in the BC1 progeny and from 24 to 37 in the BC2 progeny. All F1 hybrids were resistant to both blast and bacterial blight. One BC1 plant was moderately susceptible to blast while the rest were resistant. Thirteen of the 16 BC2 progeny tested were resistant to blast; 1 blast-resistant BC2, plant 75-1, had 24 chromosomes. A 3 resistant: 1 susceptible segregation ratio, consistent with the action of a major, dominant gene, was observed in the BC2F2 and BC2F3 generations. Five of the BC1 plants tested were resistant to bacterial blight. Ten of the 21 BC2 progeny tested were resistant to Philippine races 2, 3, and 6 of the bacterial blight pathogen. One resistant BC2, plant 78-1, had 24 chromosomes. The segregation of reactions of the BC2F2, BC2F3, and BC2F4 progenies of plant 78-1 suggested that the same or closely linked gene(s) conferred resistance to races 2, 3, 5, and 6 of the bacterial blight pathogen from the Philippines.
Drought is a major constrain in crop production that reduce growth and cause yield loss of up to 70%. Transcription factor plays a major role in cellular regulation and physical changes of plants as a response to stress. A number of transcription factors, such as CBF/DREB, NAC, zinc finger protein are regulators during stress. The Oryza sativa NAC6 (OsNAC6) gene is one of the transcription factor in rice that can regulate gene expression during stress conditions. Thus, pCambia 1305 harboring OsNAC6 chimaeric gene with CaMV 35S promoter was introduced into rice zygotic embryo using Agrobacterium tumefaciens mediated transformation to regenerate transgenic rice overexpressing the transgene. As many as 39 putative transgenic lines in which 21 lines possitively harbored hpt gene have been regenerated. The positive identification of hpt in the regenerated transgenic rice indirectly indicated integration of the targeted OsNAC6 since both transgenes were part of the same T-DNA. Further analysis indicated the presence of 1-3 copies of transgene integration in the genome. The expression of OsNAC6 transgene in the transgenic rice line#C.73, C.83 and C.91 were higher than wild type non-transgenic one. Further analysis indicated those three transgenic lines carrying OsNAC6 transgene exhibited higher tolerance against drought and salinity stresses. Moreover, three known stress-associated regulatory genes (AP2, Zincfinger protein and MYB) were up-regulated in those three transgenic lines. These findings demonstrated that OsNAC6 might be a candidate of stress-responsive NAC regulatory gene that can be used to develop either drought or salt tolerant tolerant transgenic plants.
Abstract. Nugraha Y, Utami DW, Rosdianti I, Ardie SW, Ghulammahdi M, Suwarno, Aswidinnoor H. 2016. Markers-traits association for iron toxicity tolerance in selected Indonesian rice varieties. . Ferrous iron toxicity is a mineral disorder frequently occurring under flooded soils condition where rice is cultivated. Here we study identification the Single Nucleotide Polymorphism (SNPs) markers associated with iron toxicity tolerance characters. The phenotypical data was collected from exploiting of twenty-four rice genotypes that were grown under Yoshida + 0.2% agar solution with treatment of 400 mg. L -1 Fe 2+ and control conditions. The same genotypes were grown in iron toxicity acute and control sites at Taman Bogo, Lampung Province, Indonesia. The Principle Component Analysis (PCA) of the phenotypic data showed that 18 rice genotypes were selected representing grouping of related characters to iron toxicity condition. The genotyping of selected genotypes was carried out using multiplexes of 384 SNPs Golden Gate Illumina© assay. We identified, TBGI380435 which located on 14.45 Mbp of chromosome 9 was associated to leaf bronzing and relative shoot weight characters in the greenhouse experiment. The marker was associated with heavy metal transport detoxification (HTDT). The results are expected to assist in locating the potential candidate genes or Fe toxicity tolerance and to allow for precise marker-assisted selection. This research will serve for rice improvement through marker-assisted breeding and genomic selection in Indonesia.
Grain yield of rice is determined by genotype (G), environment (E), and interaction between genotype x environment (G x E). Variety can achieve its maximum yield potential if it is grown in suitable environments. This study was aimed to determine the adaptability and the yield stability of rice genotypes grown in different environments. Sixteen rice genotypes were tested using RBD in 16 sites during the wet season of 2010/2011, and dry season of 2011. The tested rice lines were developed for resistance to pest and diseases. The experiment unit was 4 m x 5 m of plot, plants were fertilized with urea, SP36, and KCl at rates of 250 kg/ha, 100 kg/ha, and 100 kg/ha, respectively. Variable observed was grain yield per plot. Combined analyses of variance showed that there was no lines yielded higher than did check variety Conde. The AMMI analysis showed that the largest variation was contributed by the environment factors (76.49%), genotype x environment interactions (17.55%), and the smallest was contributed by the genotypes (5.97%). Data exploration using boxplot method indicated that the low contribution of the genotype x environment interaction variance in this study was due to the high degree of similarity of yield potentials among the genotypes, and due to high similarity of environmental conditions of the sites.Based on the analysis of AMMI 2, lines B12743 - MR-18-2-3-8, IPB107-F-82-2-1, and Conde was each classified as widely adapted genotypes, while G8, IPB107-F-27-6-1, and BIO111-2-BC-PIR-3714, each was considered as genotype having a specific adaptation.
The multi-canopy cropping system is considered a novel idea for increasing rice yield, derived from the concept of vertical agriculture. This method utilizes short and tall genotypes planted in the same hill. The tall plants form a canopy, and therefore the vertical harvest space can be used. The objective of the study was to determine the potential of breeding programs to develop varieties for multi-canopy cropping system in rice (Oryza sativa L.
Linkage of 23 Microsatellite Marker on Chromosome 6 and 7 to Downy Mildew Resistance on Maize. Roberdi, Hajrial Aswidinnoor, Asep Setiawan, Sutrisno, Marcia B. Pabendon, and M. Azrai. Downy mildew caused by Peronosclerospora is one of most important maize disease in several countries, including Indonesia. Parental and progenies selection based on conventional breeding is time consuming and laborious. Development of molecular biology produces many DNA markers used for selection, one of them is microsatellite. The aim of this research to identify microsatellite markers associated with downy mildew resistance on maize progeny MR-4 X AMATLCOHS-9-1-1-1-1-1-2-B, on chromosome 6 and 7. This research was consisted of two activities, phenotypic and genotypic analysis. Phenotypic analysis used 175 progenies BC 1 F 2 and both of parents. This analysis included planting of spreading row, inoculums preparation, inoculation of spreader rows, test material planting, inoculation of test material and observation. Genotypic analysis used 175 progenies BC 1 F 1 and both of parents. This analysis included DNA genome isolation, PCR analysis, electrophoresis, gel staining and data scoring. Percentage of downy mildew infections on MR-4 was 76%, while these on AMATLCOHS-9-1-1-1-1-1-2-B was 16%, and on 175 progenies had range from 10.1-100%. Out of 23 SSR, 12 markers could be mapped in chromosome 6 and 11 markers in chromosome 7. QTL analyses showed that chromosome 7 contain one QTL in position between phi082 and phi116I marker as far as 18.6 cM with 2.6 LOD value.
Iron toxicity is major constraint of rice production in irrigated-lowland. The Improvement of tolerant rice cultivar to iron toxicity requires the information of some genetics parameters related to selected characters. This study was aimed to estimate gene action and heritability of the grain yield and its component under iron-toxic stress and control field conditions in rice. The iron-toxic tolerant rice cultivars, Pokkali and Mahsuri were crossed with the sensitive cultivar, Inpara5 to develop six generation populations. The breeding materials were grown in the iron toxicity site and control in Taman Bogo, Lampung Indonesia in the wet season from December 2013 to March 2014. The sensitive parent and BC1P1 had lower stress tolerance index (STI) compared to the tolerant parent F1, F2 and BC1P2. The grain yield and its component were fitted to the best model in five parameters which were more prominent with interactive epistasis of duplicate and complementary gene action. The heritability's under control were more higher compared to iron toxicity stress condition. Delaying selection to later generations and combining with the shuttle breeding between stressed and controlled environments were the best strategy for improving the grain yield and tolerance to iron toxicity in rice.
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