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GENETICS AND GENOMICS IN RICE BREEDING - ABIOTIC STRESS

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Concurrent Session II : Genetics and Genomics in Rice Breeding -        Abiotic stress

Chairman    :    Dr.R.Samiyappan

Co-Chairman     :    Dr.Arvind Kumar

Rapporteurs    :    Dr.V.Udayasuriyan and Dr.R.Gnanam

Lecture 1    :    "Inheritance of DNA methylation in rice genome" by
                         Dr.Hisato Okuizumi, Japan.

The paper envisaged analyzing DNA methylation patterns in rice as recent reports show altered DNA methylation patterns in F1 hybrids of inter-specific and intra-specific crosses. Nipponbare, a japonica type and Kasalath, an indica type as parents and their F1    were analysed for altered
inheritance of methylated sites both from direct and reciprocal crosses using RLGS method. The study indicated both Mendalian and non – Mendalian inheritance. Methylation analysis of an abnormal spot 323 was also characterized.

Lecture 2    :    "QTL to variety for drought tolerance in rice: Recent successes and limitations" by Dr.Arvind  Kumar, IRRI, Philippines.

Dr. Arvind Kumar was commenting on selection for drought tolerance / resistance by  using secondary traits like leaf rolling, transpiration and osmotic adjustment as not a good method to bring in improvement for yield increase. Instead he suggested to look for direct selection for grain yield under stress and irrigated conditions and explained the different QTLs recovered from different donors which are in combination are targeted through MAS for development of drought resistant varieties suited to varied agro-eco systems.

Lecture 3    :    "Engineering tolerance to salinity stress using anti-apoptosis genes" by Dr. Sahadevan Mundree,    QUT, Australia.

He explained about a native grass Tripogon loliformis possessing salt and cold tolerance and the role of programmed cell death in mammals and Caenorhabditis elegans.. He mentioned about the use of BCL2 gene to confer cold tolerance and HBA G4 for drought in tobacco. A japonica ecotype, Nipponbare was used for transformation. Transformation was done with the construct containing anti- apotosis genes in pCAMBIAvector. PCR, RT-PCR and Southern blot and analysis of other physiological characters were carried out for confirmation. Later, the difference in wild and transgenic plants were compared for their survival under control and 100 mM NaCl stress 14 days after treatment.

Lecture 4    :    "Alternate insight into rice grain filling" by Dr.Ajay Kohli, IRRI, Philippines.

Dr.Ajay had identified a GLP gene , highly upregulated in rice spikelet, which he characterized on chromosome 8, as a bi-functional unit exhibiting both SOD and OXO activity. It is a maiden report in rice. The expression of Os GLP 8960 transcript was specifically observed in endosperm and spikelets. His finding suggested the possible Glyoxalate pathway including malate synthase and isocitrate lyase as possible enzymes and an anepleotic fermentation situation during grain filling.

Lecture 5    :    "Integrating marker assisted breeding in rice improvement- Achievements, challenges and  opportunities" by Dr.A.K.Singh.

Dr.A.K.Singh enumerated the different QTL’s available for resistance to Sheath blight, BLB, blast and BPH, the problems with indian rice hybrids and the necessity to develop markers to have a heterotic pool. He had analysed 566 genotypes with 60 markers, made QTL mapping for grain dimensions and MABB for provitaminAin Swarna. The highlighted challenges by him were validation of markers, molecular markers vs phenotype, optimum population size to isolate desired recombinations, foreground and background selection, use of functional markers for target traits and simultaneous analysis of perfect markers

Lecture 6    :    "Development and evaluation of rice Near Isogenic Lines for drought resistance in rainfed  production environment" by Dr. R. Suji

Dr.Suji was emphasizing the critical constitutive and adaptive root traits such as basal root thickness, root pulling force and penetration and root thickness for drought tolerance and development of NIL for these root traits. Pyramiding of QTL was done using IR20 as a recurrent parent and CT
9993-5-10 as donor, a Columbian type. QTL for basal root thickness, root pulling force and penetration and root thickness were identified. The NILs developed are being evaluated.

Lecture 7    :    "Genome assisted exploitation of land race Norungan and improvement of drought resistance in rice"    by Dr.S. Robin.

Dr.Robin had explained the reason for selecting Norungan, a land race, as a donor for drought resistance and the importance of trait identification and QTL validation at reproductive stage. Norungan was crossed with TKM9 and BC1F5 population was developed and graphical genotyping was done. Functional markers in candidate gene loci within LD value were selected and out of 5 markers,
three have significant correlation with root length, volume and thickness.

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