Agricultural Research Management Information System

Home
Research Summary
Search
About Us
- ARMIS
- Brochure
Contact Us
Report
User Request
Data Input
Help
- Operation Manual
  - PDF
  - Video
- Program Area & Commodity
We have reached 37600 number of research entries at this moment.

- Logout

Research Detail

Home
Research
Detail

Identification of Qtls for Salinity Tolerance at Reproductive Stage in Rice (oryza Sativa L.)

Mr. Hosneara Hossain
PhD Thesis
Department of Genetics and Plant Breeding, BAU, Mymensingh-2202

Abstract/ Executive Summary:

Salinity is one of the most widespread abiotic stresses in rice growing areas of the world. Salinity tolerance in rice varies for different growth stages. Rice is relatively tolerant during germination, becomes very sensitive during the early seedling stage, gains tolerance during active tillering, becomes sensitive during reproductive stage and then relatively more tolerant at maturity. Thus, the seedling and reproductive stages are the most vulnerable to salt stress and plant experience greater damage from salt stress mostly at these stages. Very poor correlation exists between tolerance at the seedling stage and during reproduction, suggesting that tolerance at these two stages is regulated by a different set of genes. The reproductive stage is most crucial as it ultimately determines grain yield. Each F2 plant was phenotyped for agronomical (plant height, tiller no., panicle no., panicle length, grain weight, grain yield and biomass) cytological (pollen fertility) and physiological characters (Na+, K+ and Na+-K+ ratio in flag leaf). For the parental polymorphism survey, 510 microsatellite and Insertion/ Deletion (InDel) markers were used out of which 131 (25.7%) were found polymorphic between the two parents were used to construct linkage map of 1458.5 cM with a mean inter-marker distance of 11.1 cM. Sixteen QTLs with significant threshold of P < 0.001 (corresponding to an interval mapping LOD > 3.0 or a composite interval mapping LOD > 3.0) were detected. The LOD value of these QTLs ranged from 3.2-22.3 with phenotypic variation explained by those QTLs range from 4- 47%. Genome-wide analysis using Map Manager QTX for all pairs of marker loci was performed and identified 29 significant epistatic (digenic) interactions which are falling into three groups: 2 interactions between QTLs, 15 interactions between complementary loci and 12 interactions between QTLs and background loci. The graphical genotyping analysis verified the position of detected QTLs for salt tolerance in this population. Results infers that Na+ concentration (mmol g-1 dwt), Na+-K+ ratio and pollen fertility are the most important mechanisms controlling the salt tolerance at reproductive stage. This is the first report on identification of novel genomic loci for reproductive-stage salt tolerance related traits in rice. The present study reports the construction of the first genetic map for this population at reproductive-stage salt tolerance in rice and demonstrates its utility for molecular mapping of QTLs controlling salinity tolerance related traits which will be useful in marker assisted selection in future.

Keywords: QTL, Salinity tolerance , Rice

Location: Mymensingh

Start Date: 04-09-2006

End Date: 29-03-2011

Program Area: Variety and Species

Commodity: Rice

Objectives:

To reveal the important mechanisms associated with salinity tolerance during reproductive development and identify underlying quantitative trait loci (QTLs).

Methodology:

This study was conducted during reproductive development and identify underlying quantitative trait loci (QTLs) or genes using contrasting rice genotypes viz. cheriviruppu and Pusa Basmati 1. Cheriviruppu is an indica rice variety highly tolerant at seedling and reproductive stages is from Kerala coast of India. Pusa Basmati 1 is an aromatic premium quality aromatic-indica rice variety sensitive to salinity at reproductive stage. These two varieties were crossed to develop F₂mapping population that was used to identify the QTLs using co-dominant molecular markers like microsatellite/ simple sequence repeat (SSR). Each F₂ plant was phenotyped agronomical (plant height, tiller number, panicle number, penicle length, grain weight, grain yield and biomass) cytological (pollen fertility) and physiological characters (Na+, K+ and Na+-K+ ratio in flag leaf. For the parental polymorphism survey, 510 microsatellite and Insertion/Deletion markers were used.

Source of Information: PhD thesis of Mr. Hosneara Hossain, Department of Genetics and Plant Breeding,BAU, Mymensingh-2202, 2011

Article Link (Online Journal):

Funding Source:

1. Government

Budget:

Total Budget (Tk.) :

Achievement/Findings:

Quantitative trait loci obtained from single marker analysis, interval mapping and composite interval mapping analysis and consistency of the QTLs was assessed using different QTL analytical tools. Genomic regions identified on chromosomes 1, 7, 8 and 10 affect salinity tolerance at reproductive stage through alterations in Na+ uptake, pollen fertility and Na+-K+ ratio are good targets for marker-assisted selection aimed at improving salinity tolerance. Three reproductive-stage salt tolerance mechanisms have been suggested: Na+ exclusion, Na+-K+ ratio and pollen fertility. Identified QTLs affect reproductive-stage salt tolerance that can improve plant breeding efficiency because this knowledge can be used to enhance marker-assisted selection and QTLs pyramiding in the future.

Knowledge Management: Thesis