What's happening at IRRI
Tuesday, May 31, 2016, 01:15pm - 02:15pm
Physiological elucidation, genetic, architecture, and metabolic landscape of tolerance to flooding during germination in rice
Frederickson D. Entila
Plant Physiology Group
Abstract: As the arable land is declining, weather is unfavorably changing, and natural resources are continually deteriorating, with the demands of dramatically bloating population, food scarcity is imminent. Furthermore, food production suffers from increasing urbanization and negative impact of climate change through loss of land, its productivity, and decline in labor forces for agricultural purposes. These emerging problems substantiate the urgent need to enhance adaptation of agriculture crops through intensification of cultivation, sustainable food systems, and augmented genetic gains. Intensification of rice production through direct-seeded rice (DSR) has been progressively practiced but wide implementation is hampered due to limited germination and poor crop establishment of existing varieties under flooded conditions. Identifying donors of tolerance to anaerobic germination (AG) will facilitate varietal improvement for DSR and will result to enhanced and ecological agriculture. The Rice Diversity Panel 1 (343 accessions) consisting of 5 subpopulations was screened for AG tolerance. Analyses revealed that most of the tolerant varieties are japonicas, with some indicas and admixed. Tolerance is attributed to fast shoot growth but substantial root extension under flooding. Relating genotypic and phenotypic components showed that the tolerance is controlled differently across subpopulations suggestive of existence of various tolerance mechanisms. Genome wide association mapping revealed that most traits had association peaks at chromosomes 1, 3, 4, 6, 9, and 11: some co-localized with known QTLs and others were novel. Candidate gene ontology analysis implied that most genes are involved in metabolic processes and functions as catalyst and in binding. However, transcriptomic network analysis revealed significant module-specific enrichments like carbohydrate metabolism*, GTPase activity*** and calcium ion homeostasis*. Upon metabolite profiling of germinating seeds under AG and normoxia, 1232 metabolites were detected, 63 were significantly up-regulated and 54 significantly down-regulated. This study provides a systems-level approach for underpinning physiological mechanism of AG: elucidating phenotypic heterogeneity, genetic architecture, transcriptomic network, and metabolic signatures from a genome-wide perspective. Apparently, populations were being developed from identified donors to facilitate breeding platform towards enhanced and sustainable rice production.
Keywords: direct seeding, anaerobic germination, genome-wide association mapping, metabolite profiling
CESD Conference Rm 1, DL Umali Bldg