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Qtl Mapping for Salinity Tolerance at Reproductive Stage of Boilam

Md. Sazzadur Rahman
Senior Scientific Officer
Plant Physiology Division, Bangladesh Rice Research Institute, Gazipur-1701

Dr. Z. I. Seraj
Professor
Dept. of Biochemistry & Molecular Biology, Dhaka University

Abstract/ Executive Summary:

Mapping of salinity QTLs in seedling stage has been worked out in Backcross population of Boilam and BRRI dhan27 to observe wheather the salinity QTLs are sharing the same map location or different in respect to different plant growth stages. Two hundred BC2F4 population of the cross Boilam and BRRI dhan27 along with parents and checks IR29, FL378, FL478, Pokkali were considered for the study. A total of 10 major QTLs were identified in chromosome 5, 6, 7, 8, 11 and 12 with LOD 4.40- 3.00 and R2 ranging from 15.60-11.00. From this work, it should target first on the QTL identified in chromosome 12, this is the same position where seedling stage QTL overlapped with two QTLs identified for reproductive stage tolerance. Second, in the chromosome 8 where 3 reproductive stage QTLs overlapped on the same marker interval and finally the QTL on the chromosome 9, this is the major effect QTL for seedling tolerance.

Keywords: Salinity, Rice, Tolerance, QTL mapping, Reproductive stage, SSR, Na+ - K+ ratio.

Location: Plant Physiology Nethouse,Bangladesh Rice Research Institute,Gazipur-1701 and Biochemistry & Molecular Lab, Dhaka University

Start Date: 01-07-2008

End Date: 30-06-2009

Program Area: Variety and Species

Commodity: Rice

Objectives:

To map QTLs/genes associated with reproductive tolerance of Boilam.

Methodology:

Two hundred BC2F4 population of the cross Boilam and BRRI dhan27 along with parents and checks IR29, FL378, FL478, Pokkali were grown in Yoshida solution (Yoshida et. al. 1976) of 16L plastic Balti under Nethouse conditions. Salt stress (EC 6 dSm^-1) was applied 1 week before panicle initiation stage (42 days after sowing) and maintained up to the maturity. Damaged symptoms like Flag leaf and Spikelets deformation were considered just after full anthesis. But the panicle exertion and other yield related traits were observed after harvesting of each line. Na+ and K+ content were measured followed by the method described by Yoshida et. al. (1976) from Flag, 2nd, 3rd leaf and Shoot (Straw mainly leaf sheath and stem) and Roots and then the Na+-K+ ratios were computed by dividing of the content on the dry weight basis. Seventy-six polymorphic SSR/Indel markers distributed whole the genome were used to genotype. Data were analysed through Windows version of QGENE softwar v4.04 with threshold LOD 3.0.

Source of Information: Proceedings of BRRI Annual Internal Review for 2008-2009)

Article Link (Online Journal):

Funding Source:

1. Government

Budget:

Total Budget (Tk.) :

Achievement/Findings:

A total of 10 major QTLs were identified in chromosome 5, 6, 7, 8, 11 and 12 with LOD 4.40- 3.00 and R2 ranging from 15.60-11.00. Interestingly three major QTLs having LOD 4.4-3.1 controlling Na+-K+ ratio of 2nd leaf and root and flag leaf damage were identified with same marker intervals RM3215-RM11255. Thus they overlapped each other sharing same region in chromosome 8. Another two QTLs, i.e. Shoot Na+ and Root Na+- K+ ratio overlapped each other in chromosome12 flanking same marker intervals R12M33-RM17. Overlapped QTLs could be same or tightly linked QTLs operating for reproductive stage tolerance by maintaining balance between Na+ to K+ in the functional leaves, shoots and roots during reproductive growth of rice. All 14 major QTLs identified in seedling and reproductive stage of Boilam should not be targeted in breeding program. From this work, it should target first on the QTL identified in chromosome 12, this is the same position where seedling stage QTL overlapped with two QTLs identified for reproductive stage tolerance. Second, in the chromosome 8 where 3 reproductive stage QTLs overlapped on the same marker interval and finally the QTL on the chromosome 9, this is the major effect QTL for seedling tolerance.

Knowledge Management: Report/Proceedings