Farmers in South East Asia are adopting rice crop establishment methods from transplanting to direct wet or dry seeding as it requires less labour and time and comparatively less energy than transplanting. In contrast...Farmers in South East Asia are adopting rice crop establishment methods from transplanting to direct wet or dry seeding as it requires less labour and time and comparatively less energy than transplanting. In contrast to irrigated condition, in rainfed lowland, direct seeding is a common practice. Early flooding controls weeds but decreases seedling establishment in direct seeded rice. Anaerobic germination is an important trait to counteract damages caused by early flooding. Management options which can help in crop establishment and improve crop growth under flooding might remove the constraints related to direct seeding. The investigation was carried out with two near isogenic lines Swarna and Swarna- Sub1. Swarna-Subl is tolerant to submergence whereas Swarna is susceptible. Seed priming was done with water and 2% Jamun （Syzygium cumini） leaf extract, and it improved seedling establishment under flooding. Acceleration of growth occurred due to seed pretreatment, which resulted longer seedling and greater accumulation of biomass. Seed priming greatly hastened the activities of total amylase and alcohol dehydrogenase in Swarna-Subl than in Swarna. Swarna-Subl outperformed Swarna when the plants were cultivated under flooding. Weed biomass decreased significantly under flooding compared to non-flooding conditions. Seed priming had positive effects on yield and yield attributing parameters both under non-flooding and early flooding conditions.展开更多
Flash flood or submergence is a common phenomenon in rice growing rainfed lowland areas that seriously affects crop establishment leading to severe yield losses. A few submergence-tolerant rice varieties have been dev...Flash flood or submergence is a common phenomenon in rice growing rainfed lowland areas that seriously affects crop establishment leading to severe yield losses. A few submergence-tolerant rice varieties have been developed by introgressing SUB1 gene into mega rice varieties of South Asia. Two of these, Swarna-Sub1 and Sambha Mahsuri-Sub1, are already released in India for the commercial cultivation. Performance of these varieties can be further enhanced through adoption of appropriate management practices both in nursery and in main field. Two on-station field experiments were conducted using Swarna-Sub1 during the wet season (kharif) of 2011 at Rice Research Station, Chinsurah, Hooghly, West Bengal (India). Results of these experiments revealed that the use of lower seeding density (25 g m-2), application of balanced doses of N-P2O5-K2O @ 80-40-40 kg ha-1 in nursery and transplanting of aged seedlings (44 days) significantly improved plant survival, yield attributing traits and grain yield. An additional N-dose of 20 kg ha-1 at 7 days after receding of flood water resulted in better post-submergence recovery and maximum grain yield. In the on-farm trials conducted at three different locations in West Bengal, nursery raising of seedlings with the application of N-P2O5-K2O @ 80-40-40 kg ha-1, transplanting them at an optimum age (35 days) and application of 20 kg·N ha-1 after 7 days of de-submergence produced maximum grain yield of Swarna-Sub1.展开更多
Single nucleotide polymorphisms and restriction digestion-based haplotype variations among 160 flood prone rice varieties were analyzed with enzymes Alu I and Cac8 I to generate polymorphisms at Sub1A and Sub1C loci ...Single nucleotide polymorphisms and restriction digestion-based haplotype variations among 160 flood prone rice varieties were analyzed with enzymes Alu I and Cac8 I to generate polymorphisms at Sub1A and Sub1C loci （conferring submergence tolerance）, respectively. Haplotype associated with phenotype was used to study the haplotype variations at Sub1A and Sub1C loci and to determine their functional influence on submergence tolerance and stem elongation. Three patterns at Sub1A locus, Sub1A0 （null allele）, Sub1A1 （does not cut） and Sub1A2 （one SNP）, and four patterns at Sub1C locus, Sub1C1, Sub1C2, Sub1C3 and Sub1C4, were generated. Both tolerant Sub1A1 and intolerant Sub1A2 had the same length, but the difference was presence of a restriction site in the Sub1A2, but absent at the Sub1A1. Further, two types of polymorphism were detected at the Sub1C, one included major length polymorphisms （165, 170 and 175 bp） and the other was a single restriction site at different position. Eight haplotypes （different combinations of the two loci）, A1C1, A1C2, A1C4, A2C2, A2C4, A0C2, A0C3 and A0C4, were detected among 160 varieties. Haplotype A1C1 was comparatively more related to haplotypes A1C2 and A1C4, having the same Sub1A allele, and these haplotypes were found only in Bangladeshi, Sri Lankan and Indian varieties. Most tolerant varieties in A1C1 haplotype showed slow elongation, having tolerant specific Sub1A1 and Sub1C1 alleles. Further, the varieties Madabaru and Kottamali （A2C2） also showed moderate level of tolerance without Sub1A1 allele. These varieties were different with FR13A and also suspected to carry different novel tolerant genes at other loci. These materials could be used for hybridization with Sub1 varieties for pyramiding additional tolerant specific alleles into a single genotype for improving submergence tolerance in rice.展开更多
Metastasis accounts for the major cause of colorectal cancer(CRC)related mortality due to the lack of effective treatments.In this study,we integrated the single-cell RNA-seq(sc RNA-seq)and bulk RNA-seq data and ident...Metastasis accounts for the major cause of colorectal cancer(CRC)related mortality due to the lack of effective treatments.In this study,we integrated the single-cell RNA-seq(sc RNA-seq)and bulk RNA-seq data and identified the transcriptional coactivator SUB1 homolog(SacSaccharomyces cerevisiae)/PC4(positive cofactor 4)associated with CRC metastasis.Elevated SUB1 expression was correlated with advanced tumor stage and poor survival in CRC.In vivo and vitro assays showed that SUB1 depletion could inhibit the invasive and metastatic abilities of CRC cells.SUB1 activated NF-κB signaling and its transcriptional target genes CXCL1 and CXCL3 to drive CRC metastasis.Mechanistically,SUB1 integrated with the E3 ubiquitin-protein ligase UBR5 and increased its protein level in CRC cells.Subsequently,the increased UBR5mainly mediated Lys11-linked polyubiquitination and degradation of NF-κB negative regulator UBXN1,thus to activate the NF-κB signaling.Overall,our study demonstrated that SUB1 promoted CRC progression by modulating UBR5/UBXN1 and activating NF-κB signaling,providing a new therapeutic strategy for treating metastatic CRC through targeting SUB1.展开更多
Flooding is one of the most hazardous natural disasters and a major stress constraint to rice production throughout the world,which results in huge economic loss.Approximately one-fourth of the global rice crops(appro...Flooding is one of the most hazardous natural disasters and a major stress constraint to rice production throughout the world,which results in huge economic loss.Approximately one-fourth of the global rice crops(approximately 40 million hectares)are grown in rainfed lowland plots that are prone to seasonal flooding.A great progress has been made during last two decades in our understanding of the mechanisms involved in adaptation and tolerance to flooding/submergence in rice.In this review,we summarized the physiological and molecular mechanisms that contribute to tolerance of flooding/submergence in rice.We also covered various features of flooding stress with special reference to rice plants,viz.different types of flooding stress,environmental characterisation of flood water,impact of flooding stress on rice plant and their morphological,physiological and metabolic responses under flooding.A brief discussion on the tolerance mechanism in rice exhibited to different types of flooding will be focused for the future crop improvement programme for development of flooding tolerant rice variety.展开更多
Submergence is a serious environmental condition that causes large loss in rice production in rain fed lowland and flood affected area. This study evaluated morphological and physiological responses of rice roots to s...Submergence is a serious environmental condition that causes large loss in rice production in rain fed lowland and flood affected area. This study evaluated morphological and physiological responses of rice roots to submergence using two tolerant rice genotypes FR13A and Swarna-Sub 1 and two sensitive ones Swarna and IR42. The tolerant genotypes had higher survival rate and less shoot elongation but greater root elongation during submergence than the sensitive ones. After submergence,the tolerant genotypes also had higher root dry weight and more active roots than the sensitive ones.Tolerant genotypes exhibited less root injury, with less malondialdehyde production and slower electrolyte leakage after submergence. Tolerant genotypes also maintained higher concentrations of soluble sugar and starch in roots and shoots and higher chlorophyll retention after submergence than the sensitive ones.Our data showed that root traits such as root activity and root growth are associated with survival rate after submergence. This is probably accomplished through higher energy supply, and membrane integrity is necessary to preserve root function and reduce injury during submergence. These root traits are important for submergence tolerance in rice.展开更多
The present study evaluated submergence responses in 88 lowland indigenous rice(Oryza sativa L.) landraces from Koraput, India, to identify submergence-tolerant rice genotypes. In pot experiments, variations in surviv...The present study evaluated submergence responses in 88 lowland indigenous rice(Oryza sativa L.) landraces from Koraput, India, to identify submergence-tolerant rice genotypes. In pot experiments, variations in survival rate, shoot elongation, relative growth index, dry matter, chlorophyll, soluble sugar and starch contents were evaluated in two consecutive years under well-drained and completely submerged conditions. Principal component analysis showed that the first three axes contributed 96.820% of the total variation among the landraces, indicating wide variation between genotypes. Major traits such as survival rate, relative growth index, soluble sugar and starch contents appeared to be important determinants of phenotypic diversity among the landraces. Phenotypic coefficient of variance was higher than genotypic coefficient of variance for all the traits and all showed high heritability(90.38%–99.54%). Five rice landraces(Samudrabali, Basnamundi, Gadaba, Surudaka and Dokarakuji) were the most tolerant to submergence. When submerged for up to 14d, Samudrabali, Basnamundi and Godoba were notable for having greater survival rates than a standard submergence tolerant variety FR13 A, and also notable for elongating more vigorously and accumulating more biomass. These three landraces may therefore be especially useful in lowland rice growing areas that are affected by both moderate stagnant water and flash flooding. Molecular genotyping revealed that the submergence tolerance of Samudrabali, Basnamundi and Godoba is linked to the presence of one or more different Sub1 loci and it may well prove useful for breeding improved submergence tolerant rice varieties, thereby assising to improve yield stability in the rainfed lowland agro-ecosystem.展开更多
In the present study a group of four indigenous and less popular rice genotypes (Meghi, Panibhasha, Jabra and Sholey) reported by growers as submergence tolerant lines from flood prone areas of south Bengal were explo...In the present study a group of four indigenous and less popular rice genotypes (Meghi, Panibhasha, Jabra and Sholey) reported by growers as submergence tolerant lines from flood prone areas of south Bengal were explored through study of nodal anatomy, physio-biochemical screening under submergence and genotyping with submergence tolerance linked rice microsatellite loci (RM loci). To identify the different allelic forms of different Sub1 compnents (Sub1A, Sub1B and Sub1C) among the studied lines, the genomic DNA of individual genotypes was amplified with three ethylene response factor like genes from Sub1 loci, located on rice chromosome 9. From the different physio-biochemical experiments performed in this investigation, it has been shown that Meghi and Jabra are the two probable potent genotypes which share common properties of both submergence tolerant and deep water nature whereas rest two genotypes (Sholey and Panibhasha) behave like typical deep water rice. The submergence tolerance property of Meghi was also confirmed from submergence tolerance linked SSR based genotyping by sharing with FR13A for some common alleles as reflected in fingerprint derived dendrogram. The rest of the genotypes shared a number of alleles and were included in a separate cluster. The common behaviour of Meghi and FR13A under submergence was also confirmed from genetic study of Sub1 loci through sharing of some common alleles for three Sub1 components (Sub1A, Sub1B and Sub1C loci). One SSR loci (RM 285) was identified as a potent molecular marker for submergence tolerance breeding programme involving these two selected rice lines (Meghi and Jabra) as donor plant through marker assisted selection.展开更多
The present investigation embodies with some distinct physiological responses of rice seedlings bearing sub1A allele when cultured under soil moisture deficit condition. In order to estimate the extent of variation of...The present investigation embodies with some distinct physiological responses of rice seedlings bearing sub1A allele when cultured under soil moisture deficit condition. In order to estimate the extent of variation of sub1A allele in cv. Swarna Sub1, few specific responses were recorded. Ongoing days (2, 4 and 8) of water stress, rice seedlings were mostly concerned with regulation of root growth through 1.24%, 4.10% and 8.96% as compared to control. When relative growth rate (RGR) of the biomass was considered, it recorded a significant down regulation maximum by 27.27% over non-stressed plants. The light absorbing capacity of foliages in terms of leaf mass ratio (15.62%) and specific leaf weight (8.45%) was also curtailed under stress contiguously with total dry matter accumulation. For light harnessing mechanism, the contributing pigments were most significantly (p ≤ 0.05) affected with maximum variation for chlorophyll (31.29%), lycopene (79.31%) and carotenoids (55.31%) over control. NAR was strikingly differed by 32.72% under water stress in average. To support the water stress related depletion of moisture tension, plants recorded RWC with a ranges of 6.62% to 21.57% under stress than control. In balance of cellular dehydration rice seedlings were recorded 6.72% loss of proline, but up-regulated the release of free amino acids by 1.35 fold. In expression of generic potential for sub1A allele, the growth inhibition even under water deficit was evident from carbohydrate depletion by 10.93%, 11.42% and 24.35% through days of treatments. This was supported by depletion of apoplastic and cellular invertase activities by 90.90% and 72.91%. The possibility for sub1A in tolerance of deficit water status in rice culture has been discussed in more details.展开更多
The result of the study contributes to enhancing and sustaining future livelihoods and food security in Vietnam vis-a-vis climate change. An innovative strategy based on marker-assisted backcrossing (MABC) was used to...The result of the study contributes to enhancing and sustaining future livelihoods and food security in Vietnam vis-a-vis climate change. An innovative strategy based on marker-assisted backcrossing (MABC) was used to transform popular rice variety AS996 into the one can tolerate submergence while maintaining its original characteristics preferred by farmers and consumers. The submergence tolerance QTL SUB1 counts for up to 70% of the submergence tolerant and provides a marked improvement of submergence tolerance in all genetic backgrounds and environments tested so far. Parental diversity was carried out with 460 markers. Of which, 53 polymorphic markers were used for assessment on BC1F1, BC2F1 and BC3F1 generations. The best BC1F1 plant was P422 with highest recipient allele was 87.5%, while the additional chosen plants were P412, P428, P215 and P39 (81% - 84%). All these plants were used to develop BC2F1 generation. The six BC2F1 plants were used to develop BC3F1 and BC2F2 were the plants number P422-11 and P422-14 having 93.75% recipient alleles and P422-12, P422-3, P39-17, P39-25 having 92.25% recipient alleles. Total of 445 BC3F1 plants were confirmed the introgresion of SUB1 using ART5 and SC3. After three generations of backcrossing, application of MABC resulted in the best BC3F1 individual P422-14-177 with 100% of recipient alleles based on the number of 53 markers used with only the introgression size of SUB1 was 0.3Mb between ART5 and SC3. Phenotyping was carried out on BC3F1 and BC2F2 of the selected lines. The survival ratio of these selected lines and IR64SUB1 were the same. It convinced the successfully introgress SUB1 into AS996 rice variety. The breeding line BC4F1 having 100% genetic background of donor variety is ready for develop new submergence tolerant rice variety ASS996-SUB1 to cope with climate change.展开更多
文摘Farmers in South East Asia are adopting rice crop establishment methods from transplanting to direct wet or dry seeding as it requires less labour and time and comparatively less energy than transplanting. In contrast to irrigated condition, in rainfed lowland, direct seeding is a common practice. Early flooding controls weeds but decreases seedling establishment in direct seeded rice. Anaerobic germination is an important trait to counteract damages caused by early flooding. Management options which can help in crop establishment and improve crop growth under flooding might remove the constraints related to direct seeding. The investigation was carried out with two near isogenic lines Swarna and Swarna- Sub1. Swarna-Subl is tolerant to submergence whereas Swarna is susceptible. Seed priming was done with water and 2% Jamun （Syzygium cumini） leaf extract, and it improved seedling establishment under flooding. Acceleration of growth occurred due to seed pretreatment, which resulted longer seedling and greater accumulation of biomass. Seed priming greatly hastened the activities of total amylase and alcohol dehydrogenase in Swarna-Subl than in Swarna. Swarna-Subl outperformed Swarna when the plants were cultivated under flooding. Weed biomass decreased significantly under flooding compared to non-flooding conditions. Seed priming had positive effects on yield and yield attributing parameters both under non-flooding and early flooding conditions.
文摘Flash flood or submergence is a common phenomenon in rice growing rainfed lowland areas that seriously affects crop establishment leading to severe yield losses. A few submergence-tolerant rice varieties have been developed by introgressing SUB1 gene into mega rice varieties of South Asia. Two of these, Swarna-Sub1 and Sambha Mahsuri-Sub1, are already released in India for the commercial cultivation. Performance of these varieties can be further enhanced through adoption of appropriate management practices both in nursery and in main field. Two on-station field experiments were conducted using Swarna-Sub1 during the wet season (kharif) of 2011 at Rice Research Station, Chinsurah, Hooghly, West Bengal (India). Results of these experiments revealed that the use of lower seeding density (25 g m-2), application of balanced doses of N-P2O5-K2O @ 80-40-40 kg ha-1 in nursery and transplanting of aged seedlings (44 days) significantly improved plant survival, yield attributing traits and grain yield. An additional N-dose of 20 kg ha-1 at 7 days after receding of flood water resulted in better post-submergence recovery and maximum grain yield. In the on-farm trials conducted at three different locations in West Bengal, nursery raising of seedlings with the application of N-P2O5-K2O @ 80-40-40 kg ha-1, transplanting them at an optimum age (35 days) and application of 20 kg·N ha-1 after 7 days of de-submergence produced maximum grain yield of Swarna-Sub1.
文摘Single nucleotide polymorphisms and restriction digestion-based haplotype variations among 160 flood prone rice varieties were analyzed with enzymes Alu I and Cac8 I to generate polymorphisms at Sub1A and Sub1C loci （conferring submergence tolerance）, respectively. Haplotype associated with phenotype was used to study the haplotype variations at Sub1A and Sub1C loci and to determine their functional influence on submergence tolerance and stem elongation. Three patterns at Sub1A locus, Sub1A0 （null allele）, Sub1A1 （does not cut） and Sub1A2 （one SNP）, and four patterns at Sub1C locus, Sub1C1, Sub1C2, Sub1C3 and Sub1C4, were generated. Both tolerant Sub1A1 and intolerant Sub1A2 had the same length, but the difference was presence of a restriction site in the Sub1A2, but absent at the Sub1A1. Further, two types of polymorphism were detected at the Sub1C, one included major length polymorphisms （165, 170 and 175 bp） and the other was a single restriction site at different position. Eight haplotypes （different combinations of the two loci）, A1C1, A1C2, A1C4, A2C2, A2C4, A0C2, A0C3 and A0C4, were detected among 160 varieties. Haplotype A1C1 was comparatively more related to haplotypes A1C2 and A1C4, having the same Sub1A allele, and these haplotypes were found only in Bangladeshi, Sri Lankan and Indian varieties. Most tolerant varieties in A1C1 haplotype showed slow elongation, having tolerant specific Sub1A1 and Sub1C1 alleles. Further, the varieties Madabaru and Kottamali （A2C2） also showed moderate level of tolerance without Sub1A1 allele. These varieties were different with FR13A and also suspected to carry different novel tolerant genes at other loci. These materials could be used for hybridization with Sub1 varieties for pyramiding additional tolerant specific alleles into a single genotype for improving submergence tolerance in rice.
基金supported by the National Natural Science Foundation of China(82073229,82072623)。
文摘Metastasis accounts for the major cause of colorectal cancer(CRC)related mortality due to the lack of effective treatments.In this study,we integrated the single-cell RNA-seq(sc RNA-seq)and bulk RNA-seq data and identified the transcriptional coactivator SUB1 homolog(SacSaccharomyces cerevisiae)/PC4(positive cofactor 4)associated with CRC metastasis.Elevated SUB1 expression was correlated with advanced tumor stage and poor survival in CRC.In vivo and vitro assays showed that SUB1 depletion could inhibit the invasive and metastatic abilities of CRC cells.SUB1 activated NF-κB signaling and its transcriptional target genes CXCL1 and CXCL3 to drive CRC metastasis.Mechanistically,SUB1 integrated with the E3 ubiquitin-protein ligase UBR5 and increased its protein level in CRC cells.Subsequently,the increased UBR5mainly mediated Lys11-linked polyubiquitination and degradation of NF-κB negative regulator UBXN1,thus to activate the NF-κB signaling.Overall,our study demonstrated that SUB1 promoted CRC progression by modulating UBR5/UBXN1 and activating NF-κB signaling,providing a new therapeutic strategy for treating metastatic CRC through targeting SUB1.
文摘Flooding is one of the most hazardous natural disasters and a major stress constraint to rice production throughout the world,which results in huge economic loss.Approximately one-fourth of the global rice crops(approximately 40 million hectares)are grown in rainfed lowland plots that are prone to seasonal flooding.A great progress has been made during last two decades in our understanding of the mechanisms involved in adaptation and tolerance to flooding/submergence in rice.In this review,we summarized the physiological and molecular mechanisms that contribute to tolerance of flooding/submergence in rice.We also covered various features of flooding stress with special reference to rice plants,viz.different types of flooding stress,environmental characterisation of flood water,impact of flooding stress on rice plant and their morphological,physiological and metabolic responses under flooding.A brief discussion on the tolerance mechanism in rice exhibited to different types of flooding will be focused for the future crop improvement programme for development of flooding tolerant rice variety.
基金supported by German Federal Ministry from Economic Cooperation and Development (BMZ)
文摘Submergence is a serious environmental condition that causes large loss in rice production in rain fed lowland and flood affected area. This study evaluated morphological and physiological responses of rice roots to submergence using two tolerant rice genotypes FR13A and Swarna-Sub 1 and two sensitive ones Swarna and IR42. The tolerant genotypes had higher survival rate and less shoot elongation but greater root elongation during submergence than the sensitive ones. After submergence,the tolerant genotypes also had higher root dry weight and more active roots than the sensitive ones.Tolerant genotypes exhibited less root injury, with less malondialdehyde production and slower electrolyte leakage after submergence. Tolerant genotypes also maintained higher concentrations of soluble sugar and starch in roots and shoots and higher chlorophyll retention after submergence than the sensitive ones.Our data showed that root traits such as root activity and root growth are associated with survival rate after submergence. This is probably accomplished through higher energy supply, and membrane integrity is necessary to preserve root function and reduce injury during submergence. These root traits are important for submergence tolerance in rice.
文摘The present study evaluated submergence responses in 88 lowland indigenous rice(Oryza sativa L.) landraces from Koraput, India, to identify submergence-tolerant rice genotypes. In pot experiments, variations in survival rate, shoot elongation, relative growth index, dry matter, chlorophyll, soluble sugar and starch contents were evaluated in two consecutive years under well-drained and completely submerged conditions. Principal component analysis showed that the first three axes contributed 96.820% of the total variation among the landraces, indicating wide variation between genotypes. Major traits such as survival rate, relative growth index, soluble sugar and starch contents appeared to be important determinants of phenotypic diversity among the landraces. Phenotypic coefficient of variance was higher than genotypic coefficient of variance for all the traits and all showed high heritability(90.38%–99.54%). Five rice landraces(Samudrabali, Basnamundi, Gadaba, Surudaka and Dokarakuji) were the most tolerant to submergence. When submerged for up to 14d, Samudrabali, Basnamundi and Godoba were notable for having greater survival rates than a standard submergence tolerant variety FR13 A, and also notable for elongating more vigorously and accumulating more biomass. These three landraces may therefore be especially useful in lowland rice growing areas that are affected by both moderate stagnant water and flash flooding. Molecular genotyping revealed that the submergence tolerance of Samudrabali, Basnamundi and Godoba is linked to the presence of one or more different Sub1 loci and it may well prove useful for breeding improved submergence tolerant rice varieties, thereby assising to improve yield stability in the rainfed lowland agro-ecosystem.
文摘In the present study a group of four indigenous and less popular rice genotypes (Meghi, Panibhasha, Jabra and Sholey) reported by growers as submergence tolerant lines from flood prone areas of south Bengal were explored through study of nodal anatomy, physio-biochemical screening under submergence and genotyping with submergence tolerance linked rice microsatellite loci (RM loci). To identify the different allelic forms of different Sub1 compnents (Sub1A, Sub1B and Sub1C) among the studied lines, the genomic DNA of individual genotypes was amplified with three ethylene response factor like genes from Sub1 loci, located on rice chromosome 9. From the different physio-biochemical experiments performed in this investigation, it has been shown that Meghi and Jabra are the two probable potent genotypes which share common properties of both submergence tolerant and deep water nature whereas rest two genotypes (Sholey and Panibhasha) behave like typical deep water rice. The submergence tolerance property of Meghi was also confirmed from submergence tolerance linked SSR based genotyping by sharing with FR13A for some common alleles as reflected in fingerprint derived dendrogram. The rest of the genotypes shared a number of alleles and were included in a separate cluster. The common behaviour of Meghi and FR13A under submergence was also confirmed from genetic study of Sub1 loci through sharing of some common alleles for three Sub1 components (Sub1A, Sub1B and Sub1C loci). One SSR loci (RM 285) was identified as a potent molecular marker for submergence tolerance breeding programme involving these two selected rice lines (Meghi and Jabra) as donor plant through marker assisted selection.
文摘The present investigation embodies with some distinct physiological responses of rice seedlings bearing sub1A allele when cultured under soil moisture deficit condition. In order to estimate the extent of variation of sub1A allele in cv. Swarna Sub1, few specific responses were recorded. Ongoing days (2, 4 and 8) of water stress, rice seedlings were mostly concerned with regulation of root growth through 1.24%, 4.10% and 8.96% as compared to control. When relative growth rate (RGR) of the biomass was considered, it recorded a significant down regulation maximum by 27.27% over non-stressed plants. The light absorbing capacity of foliages in terms of leaf mass ratio (15.62%) and specific leaf weight (8.45%) was also curtailed under stress contiguously with total dry matter accumulation. For light harnessing mechanism, the contributing pigments were most significantly (p ≤ 0.05) affected with maximum variation for chlorophyll (31.29%), lycopene (79.31%) and carotenoids (55.31%) over control. NAR was strikingly differed by 32.72% under water stress in average. To support the water stress related depletion of moisture tension, plants recorded RWC with a ranges of 6.62% to 21.57% under stress than control. In balance of cellular dehydration rice seedlings were recorded 6.72% loss of proline, but up-regulated the release of free amino acids by 1.35 fold. In expression of generic potential for sub1A allele, the growth inhibition even under water deficit was evident from carbohydrate depletion by 10.93%, 11.42% and 24.35% through days of treatments. This was supported by depletion of apoplastic and cellular invertase activities by 90.90% and 72.91%. The possibility for sub1A in tolerance of deficit water status in rice culture has been discussed in more details.
文摘The result of the study contributes to enhancing and sustaining future livelihoods and food security in Vietnam vis-a-vis climate change. An innovative strategy based on marker-assisted backcrossing (MABC) was used to transform popular rice variety AS996 into the one can tolerate submergence while maintaining its original characteristics preferred by farmers and consumers. The submergence tolerance QTL SUB1 counts for up to 70% of the submergence tolerant and provides a marked improvement of submergence tolerance in all genetic backgrounds and environments tested so far. Parental diversity was carried out with 460 markers. Of which, 53 polymorphic markers were used for assessment on BC1F1, BC2F1 and BC3F1 generations. The best BC1F1 plant was P422 with highest recipient allele was 87.5%, while the additional chosen plants were P412, P428, P215 and P39 (81% - 84%). All these plants were used to develop BC2F1 generation. The six BC2F1 plants were used to develop BC3F1 and BC2F2 were the plants number P422-11 and P422-14 having 93.75% recipient alleles and P422-12, P422-3, P39-17, P39-25 having 92.25% recipient alleles. Total of 445 BC3F1 plants were confirmed the introgresion of SUB1 using ART5 and SC3. After three generations of backcrossing, application of MABC resulted in the best BC3F1 individual P422-14-177 with 100% of recipient alleles based on the number of 53 markers used with only the introgression size of SUB1 was 0.3Mb between ART5 and SC3. Phenotyping was carried out on BC3F1 and BC2F2 of the selected lines. The survival ratio of these selected lines and IR64SUB1 were the same. It convinced the successfully introgress SUB1 into AS996 rice variety. The breeding line BC4F1 having 100% genetic background of donor variety is ready for develop new submergence tolerant rice variety ASS996-SUB1 to cope with climate change.
