Prasad Dokku - Academia.edu (original) (raw)

Papers by Prasad Dokku

Journal of applied genetics, Jan 17, 2018

Grain shape and size influence yield and consumer preferences in rice. In the present study, we c... more Grain shape and size influence yield and consumer preferences in rice. In the present study, we characterized and mapped a short and bold grained mutant and named it as TEMS5032, as the mutant is a result of EMS-induced transition from C to T at the 5032nd bp of SRS3 gene, which is known to affect grain size in rice. The substitution led to creation of a stop codon in the motor domain of SRS3, a kinesin 13 family gene, translating into a truncated protein product. However, transcription of this gene remained unaffected in TEMS5032 compared to the wild type, N22. Further, the mutation was found to affect 13 of the 25 cell cycle-related genes as they showed differential expression with respect to N22. Based on rate of grain filling, dry matter accumulation in the endosperm and histological studies, the effect of mutation in TEMS5032 was found to be similar to a known variant, TCM758, but less severe than sar1 mutant. Sequencing of 88 rice germplasm lines in the kinesin motor domain re...

Journal of Genetics, 2014

Euphytica, 2013

Grain size is one of the three productivity related traits in rice and hence a major target for g... more Grain size is one of the three productivity related traits in rice and hence a major target for genetic improvement. Since understanding genetic variation in grain size between Basmati and indica genotypes is important for rice improvement, a recombinant inbred population was developed from a traditional aromatic cultivar 'Basmati 370' and a non-aromatic indica genotype 'IRBB60'. This population was phenotyped in two locations for grain length (GL), grain breadth (GB), GL/GB ratio (LBR) and grain weight (GW). Though the RIL population reported in the current study exhibited segregation distortion (SD) for 54 % of the markers, they were utilized in analysis using an appropriate statistical package, PROC QTL in the SAS environment. Interval mapping revealed a total of 15 QTLs for GL, seven for GB, 15 for LBR and two for GW. Among them 13 were not reported earlier and thus novel. For a known major QTL identified in the study, GW8 for GB, a PCR based functional marker was designed and validated. This is the first report wherein a very high proportion of markers ([50 %) exhibiting SD have been successfully used for QTL mapping.

ORYZA-An International Journal on Rice, 2013

Plant height and flowering time are two of the important traits that affect plant architecture. E... more Plant height and flowering time are two of the important traits that affect plant architecture. Efforts were made in this study to characterize morphologically the-EMS-induced dwarf and early flowering mutants of rice variety Nagina22 and to study their mode of inheritance. Nine true breeding mutants generated earlier by EMS treatment were analysed for differences in their phenotypic characteristics recorded according to the national guidelines for Distinctness, Uniformity and Stability (DUS). The mutants exhibited variation from Nagina22 for maximum of 11 DUS characteristics to a minimum of 4 DUS descriptors, while retaining majority of the wild type features. Plant height of the dwarf mutants ranged from 69 to 101cm, while tiller number was in the range of 9 to 60. The early flowering mutants were weak in their plant stature, but flowered approximately 20–25 days earlier than Nagina22. Significant correlation among various traits of the selected mutants was observed. The mutant tr...

AoB plants, Jan 27, 2015

Water stress is one of the most severe constraints to crop productivity. Plants display a variety... more Water stress is one of the most severe constraints to crop productivity. Plants display a variety of physiological and biochemical responses both at cellular and whole organism level upon sensing water stress. Leaf rolling, stomatal closure, deeper root penetration, higher relative water content and better osmotic adjustment are some of the mechanisms plants employ to overcome water stress. In the current study, we report a mutant, ewst1 with enhanced water stress tolerance, identified from the EMS induced mutant population of rice variety Nagina22, by field screening followed by withdrawal of irrigation in pots and hydroponics (PEG 6000). Though ewst1 was morphologically similar to the wild type (WT) for 35 of the 38 morphological descriptors (except chalky endosperm/expression of white core, decorticated grain colour and grain weight), it showed enhanced germination in PEG infused medium. It exhibited increased maximum root length without increase in its root weight, root volume a...

Euphytica, 2013

ABSTRACT Breeding for resistance against Bacterial blight (BB), a destructive disease in rice, is... more ABSTRACT Breeding for resistance against Bacterial blight (BB), a destructive disease in rice, is a major challenge because of the rich diversity of the pathogen, Xanthomonas oryzae pv. oryzae. Three resistance genes i.e. xa5, xa13 and Xa21 were transferred from IRBB 60 through marker-assisted backcross breeding to supplement the Xa4 gene present in Tapaswini, an elite cultivar having a wide coverage. The precise transfer was aided through effective foreground selection using STS markers RG 556, RG 136 and pTA248 linked to the three target genes, respectively. In the screening assays, the gene pyramids having four genes exhibited higher level of resistance against the disease. Background selection based on morphological and grain quality traits and SSR markers led to the recovery of 85–96 % of the recurrent parent genome in the gene pyramids. Multi location evaluation conducted over a two year period at several hotspot locations of bacterial blight in India has resulted in identification and release of CRMAS 2622-7-6 (IT-6), a promising gene pyramid as improved Tapaswini. The high levels of resistance exhibited in the improved genotype without any yield penalty and its similarity to the recurrent parent provides a successful demonstration of the potential of MAS in pyramiding genes as well as the recovery of the parental genome with high accuracy.

Biotechnology Letters, 2013

To incorporate durable resistance against bacterial blight, a major disease rice, three resistanc... more To incorporate durable resistance against bacterial blight, a major disease rice, three resistance genes, xa 5, xa13 and Xa21, from IRBB 60 were transferred through marker-assisted backcrossing using RG 556, RG 136 and pTA248 markers linked to the three genes to supplement the Xa4 gene present in Lalat, a popular rice cultivar. Effective selection enabled the transfer in three back-crosses and a generation of selfing and background selection employing morphological and grain quality traits and molecular markers, led to >90 % recovery of the recurrent parental genome. The gene pyramids exhibited high levels of resistance against the pathogen in multi-location evaluation trials conducted over several locations of bacterial blight in India. IL-2 (CRMAS2621-7-1), a gene pyramid, was identified as being promising for several endemic regions of bacterial blight and was released as Improved Lalat in one of the identified regions. The success of the study demonstrates the vast potential of marker-assisted selection for gene stacking and recovery of the parental genome with high precision.

Journal of genetics, 2014

Dwarf plant height and tillering ability are two of the most important agronomic traits that dete... more Dwarf plant height and tillering ability are two of the most important agronomic traits that determine the plant architecture, and have profound influence on grain yield in rice. To understand the molecular mechanism controlling these two traits, an EMS-induced recessive dwarf and increased tillering1 (dit1) mutant was characterized. The mutant showed proportionate reduction in each internode as compared to wild type revealing that it belonged to the category of dn-type of dwarf mutants. Besides, exogenous application of GA3 and 24-epibrassinolide, did not have any effect on the phenotype of the mutant. The gene was mapped on the long arm of chromosome 4, identified through positional candidate approach and verified by cosegregation analysis. It was found to encode carotenoid cleavage dioxygenase7 (CCD7) and identified as an allele of htd1. The mutant carried substitution of two nucleotides CC to AA in the sixth exon of the gene that resulted in substitution of serine by a stop codo...

Journal of applied genetics, Jan 17, 2018

Grain shape and size influence yield and consumer preferences in rice. In the present study, we c... more Grain shape and size influence yield and consumer preferences in rice. In the present study, we characterized and mapped a short and bold grained mutant and named it as TEMS5032, as the mutant is a result of EMS-induced transition from C to T at the 5032nd bp of SRS3 gene, which is known to affect grain size in rice. The substitution led to creation of a stop codon in the motor domain of SRS3, a kinesin 13 family gene, translating into a truncated protein product. However, transcription of this gene remained unaffected in TEMS5032 compared to the wild type, N22. Further, the mutation was found to affect 13 of the 25 cell cycle-related genes as they showed differential expression with respect to N22. Based on rate of grain filling, dry matter accumulation in the endosperm and histological studies, the effect of mutation in TEMS5032 was found to be similar to a known variant, TCM758, but less severe than sar1 mutant. Sequencing of 88 rice germplasm lines in the kinesin motor domain re...

Journal of applied genetics, Jan 17, 2018

Grain shape and size influence yield and consumer preferences in rice. In the present study, we c... more Grain shape and size influence yield and consumer preferences in rice. In the present study, we characterized and mapped a short and bold grained mutant and named it as TEMS5032, as the mutant is a result of EMS-induced transition from C to T at the 5032nd bp of SRS3 gene, which is known to affect grain size in rice. The substitution led to creation of a stop codon in the motor domain of SRS3, a kinesin 13 family gene, translating into a truncated protein product. However, transcription of this gene remained unaffected in TEMS5032 compared to the wild type, N22. Further, the mutation was found to affect 13 of the 25 cell cycle-related genes as they showed differential expression with respect to N22. Based on rate of grain filling, dry matter accumulation in the endosperm and histological studies, the effect of mutation in TEMS5032 was found to be similar to a known variant, TCM758, but less severe than sar1 mutant. Sequencing of 88 rice germplasm lines in the kinesin motor domain re...

Journal of Genetics, 2014

Euphytica, 2013

Grain size is one of the three productivity related traits in rice and hence a major target for g... more Grain size is one of the three productivity related traits in rice and hence a major target for genetic improvement. Since understanding genetic variation in grain size between Basmati and indica genotypes is important for rice improvement, a recombinant inbred population was developed from a traditional aromatic cultivar 'Basmati 370' and a non-aromatic indica genotype 'IRBB60'. This population was phenotyped in two locations for grain length (GL), grain breadth (GB), GL/GB ratio (LBR) and grain weight (GW). Though the RIL population reported in the current study exhibited segregation distortion (SD) for 54 % of the markers, they were utilized in analysis using an appropriate statistical package, PROC QTL in the SAS environment. Interval mapping revealed a total of 15 QTLs for GL, seven for GB, 15 for LBR and two for GW. Among them 13 were not reported earlier and thus novel. For a known major QTL identified in the study, GW8 for GB, a PCR based functional marker was designed and validated. This is the first report wherein a very high proportion of markers ([50 %) exhibiting SD have been successfully used for QTL mapping.

ORYZA-An International Journal on Rice, 2013

Plant height and flowering time are two of the important traits that affect plant architecture. E... more Plant height and flowering time are two of the important traits that affect plant architecture. Efforts were made in this study to characterize morphologically the-EMS-induced dwarf and early flowering mutants of rice variety Nagina22 and to study their mode of inheritance. Nine true breeding mutants generated earlier by EMS treatment were analysed for differences in their phenotypic characteristics recorded according to the national guidelines for Distinctness, Uniformity and Stability (DUS). The mutants exhibited variation from Nagina22 for maximum of 11 DUS characteristics to a minimum of 4 DUS descriptors, while retaining majority of the wild type features. Plant height of the dwarf mutants ranged from 69 to 101cm, while tiller number was in the range of 9 to 60. The early flowering mutants were weak in their plant stature, but flowered approximately 20–25 days earlier than Nagina22. Significant correlation among various traits of the selected mutants was observed. The mutant tr...

AoB plants, Jan 27, 2015

Water stress is one of the most severe constraints to crop productivity. Plants display a variety... more Water stress is one of the most severe constraints to crop productivity. Plants display a variety of physiological and biochemical responses both at cellular and whole organism level upon sensing water stress. Leaf rolling, stomatal closure, deeper root penetration, higher relative water content and better osmotic adjustment are some of the mechanisms plants employ to overcome water stress. In the current study, we report a mutant, ewst1 with enhanced water stress tolerance, identified from the EMS induced mutant population of rice variety Nagina22, by field screening followed by withdrawal of irrigation in pots and hydroponics (PEG 6000). Though ewst1 was morphologically similar to the wild type (WT) for 35 of the 38 morphological descriptors (except chalky endosperm/expression of white core, decorticated grain colour and grain weight), it showed enhanced germination in PEG infused medium. It exhibited increased maximum root length without increase in its root weight, root volume a...

Euphytica, 2013

ABSTRACT Breeding for resistance against Bacterial blight (BB), a destructive disease in rice, is... more ABSTRACT Breeding for resistance against Bacterial blight (BB), a destructive disease in rice, is a major challenge because of the rich diversity of the pathogen, Xanthomonas oryzae pv. oryzae. Three resistance genes i.e. xa5, xa13 and Xa21 were transferred from IRBB 60 through marker-assisted backcross breeding to supplement the Xa4 gene present in Tapaswini, an elite cultivar having a wide coverage. The precise transfer was aided through effective foreground selection using STS markers RG 556, RG 136 and pTA248 linked to the three target genes, respectively. In the screening assays, the gene pyramids having four genes exhibited higher level of resistance against the disease. Background selection based on morphological and grain quality traits and SSR markers led to the recovery of 85–96 % of the recurrent parent genome in the gene pyramids. Multi location evaluation conducted over a two year period at several hotspot locations of bacterial blight in India has resulted in identification and release of CRMAS 2622-7-6 (IT-6), a promising gene pyramid as improved Tapaswini. The high levels of resistance exhibited in the improved genotype without any yield penalty and its similarity to the recurrent parent provides a successful demonstration of the potential of MAS in pyramiding genes as well as the recovery of the parental genome with high accuracy.

Biotechnology Letters, 2013

To incorporate durable resistance against bacterial blight, a major disease rice, three resistanc... more To incorporate durable resistance against bacterial blight, a major disease rice, three resistance genes, xa 5, xa13 and Xa21, from IRBB 60 were transferred through marker-assisted backcrossing using RG 556, RG 136 and pTA248 markers linked to the three genes to supplement the Xa4 gene present in Lalat, a popular rice cultivar. Effective selection enabled the transfer in three back-crosses and a generation of selfing and background selection employing morphological and grain quality traits and molecular markers, led to >90 % recovery of the recurrent parental genome. The gene pyramids exhibited high levels of resistance against the pathogen in multi-location evaluation trials conducted over several locations of bacterial blight in India. IL-2 (CRMAS2621-7-1), a gene pyramid, was identified as being promising for several endemic regions of bacterial blight and was released as Improved Lalat in one of the identified regions. The success of the study demonstrates the vast potential of marker-assisted selection for gene stacking and recovery of the parental genome with high precision.

Journal of genetics, 2014

Dwarf plant height and tillering ability are two of the most important agronomic traits that dete... more Dwarf plant height and tillering ability are two of the most important agronomic traits that determine the plant architecture, and have profound influence on grain yield in rice. To understand the molecular mechanism controlling these two traits, an EMS-induced recessive dwarf and increased tillering1 (dit1) mutant was characterized. The mutant showed proportionate reduction in each internode as compared to wild type revealing that it belonged to the category of dn-type of dwarf mutants. Besides, exogenous application of GA3 and 24-epibrassinolide, did not have any effect on the phenotype of the mutant. The gene was mapped on the long arm of chromosome 4, identified through positional candidate approach and verified by cosegregation analysis. It was found to encode carotenoid cleavage dioxygenase7 (CCD7) and identified as an allele of htd1. The mutant carried substitution of two nucleotides CC to AA in the sixth exon of the gene that resulted in substitution of serine by a stop codo...

Journal of applied genetics, Jan 17, 2018

Grain shape and size influence yield and consumer preferences in rice. In the present study, we c... more Grain shape and size influence yield and consumer preferences in rice. In the present study, we characterized and mapped a short and bold grained mutant and named it as TEMS5032, as the mutant is a result of EMS-induced transition from C to T at the 5032nd bp of SRS3 gene, which is known to affect grain size in rice. The substitution led to creation of a stop codon in the motor domain of SRS3, a kinesin 13 family gene, translating into a truncated protein product. However, transcription of this gene remained unaffected in TEMS5032 compared to the wild type, N22. Further, the mutation was found to affect 13 of the 25 cell cycle-related genes as they showed differential expression with respect to N22. Based on rate of grain filling, dry matter accumulation in the endosperm and histological studies, the effect of mutation in TEMS5032 was found to be similar to a known variant, TCM758, but less severe than sar1 mutant. Sequencing of 88 rice germplasm lines in the kinesin motor domain re...