Quantitative Trait Loci Associated with Root Elongation Ability of Rice under Nitrogen-deficient Condition

Jennifer M. Manangkil1,2, Jonathan M. Niones1, Jerwin R. Undan2, Mitsuhiro Obara3,
Teodora E. Mananghaya1, Rachelle P. Mallari1, Maybell DM. Banting1,
Sherilyn B. Estrada4, Mark Philip B. Castillo1, and Roel R. Suralta5*

1Genetic Resources Division, Philippine Rice Research Institute, Maligaya,
Science City of Muñoz, Nueva Ecija 3119 Philippines
2Biotechnology and Analytical Laboratory, Central Luzon State University,
Science City of Muñoz, Nueva Ecija 3119 Philippines
3Japan International Research Center for Agricultural Sciences,
Tsukuba, Ibaraki Prefecture 305-8686 Japan
4Plant Breeding and Biotechnology Division, Philippine Rice Research Institute,
Maligaya, Science City of Muñoz, Nueva Ecija 3119 Philippines
5Crop Biotechnology Center, Philippine Rice Research Institute, Maligaya,
Science City of Muñoz, Nueva Ecija 3119 Philippines

*Corresponding author: rrsmfs@yahoo.com

 

ABSTRACT

Nitrogen (N) is an important nutrient influencing the growth and yield in rice. Root plasticity is a key trait in the higher uptake of nutrient from the soil, especially in conditions where some major nutrients such as N is under optimal. In this study, a total of 168 BC1F4 mapping population from a cross between Malay 2 and US-2 and their parents were grown in hydroponics with deficient (5 µM) and sufficient (500 µM) N for 8 days to identify putative quantitative trait loci (QTLs) associated with root elongation. Eighty-three (83) markers were used in QTL detection using composite interval mapping. Results showed that US-2 had significantly greater shoot length and number of nodal roots than Malay 2 under N-deficient conditions. Around 19.6 and 26.8% of the population in N-deficient and N-sufficient conditions, respectively, had either longer or similar seminal root length compared with US-2. For the allele distribution, 43.1% of the population had homozygous allele for Malay 2, 20.9% had homozygous allele for US-2, and 8.4% had heterozygous allele for both parents. A total of eight putative QTLs associated with seminal root length (qSRL11.1 and qSRL2.1); number of nodal roots (qNNR6.1, qNNR11.1, and qNNR11.2); root dry weight (qRDW11.1 and qRDW11.2); and shoot length (qSL2.1) in chromosome 2, 6, and 11 regions were detected under both N treatments.