utilizing genomic resources for understanding the stay-green qtls interactions in sorghum
TRANSCRIPT
About ICRISAT: www.icrisat.orgICRISAT’s scientific information: http://EXPLOREit.icrisat.org
Feb 2017
Poster- IDT7-054Utilizing genomic resources for understanding the
stay-green QTLs interactions in SorghumManasa K G1, Santosh P Deshpande1*
1International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, India* Email: [email protected]
Abstract Sorghum [Sorghum bicolor (L.) Moench] is a fifth most important cereal crop in the world providing food, fodder/forage and bio-fuel. The postrainy sorghum crop in India isgrown on residual moisture and inadvertently faces terminal drought. “Stay-green” (delayed senescence) is a post-flowering drought tolerance response, which help plants to maintainphotosynthetically active leaf area and continue to fill their grains normally under stress. Sorghum crop is referred to express functional type of stay-green and the trait has been mappedto six major QTLs viz., Stg1, Stg2, Stg3A, Stg3B, StgC and Stg4. However, the gap in understanding the key mechanism has not been deciphered clearly. In this scenario to understandthe actual mechanism of the stay-green pathway the information from different crops on candidate genes responsible for stay-green phenotype were considered viz., STAY-GREEN (SGR)along with one or two homologous (SGR1or NYE1/SGRL); Pheophytin Pheophorbide Hydrolase (PPH); Pheophorbide a Oxygenase (PAO); Red Chlorophyll Catabolite Reductase(RCCR); Non-Yellow Coloring (NYC) and it’s homologous NYC1-Like (NOL); 7-Hydroxymethyl Chlorophyll a Reductase (HCAR) from Zea mays, Arabidopsis thaliana and Orzyasativa. Apart from these, senescence associated genes SAG2, SAG102 and SAG39 were also considered from Arabidopsis thaliana and Orzya sativa respectively. The sequence andfunctional/annotation information for these genes retrieved for sequence similarity search and it has revealed 45 to 88 % of similarity in sorghum. The mapping of these candidate genesequences within the defined QTL regions contributing for Stay-green has given an insight to utilize the re-sequencing data for improved drought tolerance in sorghum.
Hypothetical understanding of stay green trait in sorghum based on the review of stay green associated genes in Arabidopsis thaliana(Reference: Sakuraba et al, 2015, molcells.0039; Thomas, H. and Howarth, C.J. 2000, J.Exp. Bot. 51, 329-337.)
RCCRHCAR
PPH
NYC
PAONOL
Senescence triggering (SAG)
Abiotic stress at maturity(Post flowering)
Senescence associated complex
Senescence
Genes responsible for regular transition from vegetative to
senescenceStg A, Stg B
Genes responsible for regular transition from vegetative to
senescenceStg A, Stg B
HCARRCCR
PPH
NYC
PAO
NOL
Stress induced signaling
Unknown gene Stg Z
Senescence triggering (SAG)
At maturity
Senescence associated complex
Genes responsible for regular transition from vegetative to
senescenceStg A, Stg B
Genes responsible for regular transition from vegetative to
senescenceStg A, Stg B
HCARRCCR
PPH
NYC
PAO
NOL
Senescence
RCCRHCAR
PPH
NYC
PAONOL
Candidate gene information from differentmodel organisms were considered to constructcircos and check synteny among differentspecies with respect to sorghum. SGR and it’shomologous genes were mapped to Stg3A andStg3B QTLs of SBI-02 indicating these couldbe putative candidates. However other genesinvolved in the mechanism were mapped toother major and minor QTLs located on SBI-01, SBI-03, SBI-05 and SBI-07.
Protein sequence for SGR gene was retrievedfrom Genome database, Multiple sequencealignment using T-coffee software was done tocompare the homology. Highest percentagesimilarity was observed with Zea mays up to88% indicating the presence of similar kind ofcandidate gene for Stay-green in Sorghum.
Results and Conclusions
Acknowledgements
Conclusions
Reviewing the reports on Stay-green candidate gene studies from other organisms and comparing the results at gene (Circos), protein (alignment) and mechanism(Hypothesis) level helped in understanding the relationship between senescence and stay-green trait. Many of the genes involved in the mechanism are mapped to knownStay-green QTL regions giving insight to utilize the re-sequencing data to address knowledge gap for developing tools /markers and their utilization in breeding forbetter adaptation to drought scenarios.
Financial support from GCP, ACIAR and CRP-DC is greatly acknowledged.
Alignment of SGR Protein sequences from Arabidopsis, rice, maizeand sorghum using T-coffee software for comparison
Analogy of Stay-green candidate genes from other modelorganism viz., Arabidopsis, rice and maize on sorghum genome.
Linkage map of Sorghum Stay-green QTLs
Stg 4