Jung-Hyun Lim, and Nam-Chon Paek

Plant Breeding and Biotechnology 2015;3:95-107

Published online July 1, 2015;  http://dx.doi.org/10.9787/PBB.2015.3.2.095

© 2015 Korean Society of Breeding Science.

Received June 8, 2015; Revised June 24, 2015; Accepted June 26, 2015.

ABSTRACT

Functional stay-green (FSG) delays leaf yellowing, maintaining photosynthetic competence, whereas nonfunctional stay-green (NFSG) retains only leaf greenness without sustaining photosynthetic activity. Retention of chlorophylls and photosynthetic capacity is important for increasing crop yield. We determined the main-effect quantitative trait loci (QTLs) for FSG traits in the japonica rice SNU-SG1 and isolated candidate genes. To identify QTLs influencing FSG, we analyzed eight traits: (1) 1 day after heading-degree of chlorophyll content of flag leaf, (2) 1 day after heading-degree of chlorophyll content of second leaf, (3) 1 day after heading-degree of chlorophyll content of flag and second leaves, (4) 50 day after heading-degree of chlorophyll content of flag leaf, (5) 50 day after heading-degree of chlorophyll content of second leaf, (6) 50 day after heading-degree of chlorophyll content of flag and second leaves, (7) relative decline degree of chlorophyll content of flag and second leaves, and (8) flowering time. We carried out QTL analysis with F₇ RIL from a cross of japonica rice ‘SNU-SG1’ and indica rice ‘Milyang23 (M23)’. Using 131 molecular markers, we identified 18 QTLs for the eight traits with a threshold LOD value > 2.8. Sequence analysis identified 16 candidate genes for 10 main-effect QTLs. Of these, we have chosen seven strong candidate genes for the 10 main-effect QTLs. These genetic resources will be useful for breeding high-yielding rice cultivars.

Keywords : Candidate gene, Functional stay-green, Heading date, Quantitative trait locus, Rice, Whole genome resequencing

Fig. 2. Chromosomal locations of QTLs detected by Q-genes in the F7RIL population of SNU-SG1/M23. Chromosomes are numbered at the top and markers are listed on the right of each chromosome. Various geometric figures indicate the location of peak LODs of the eight traits. Chromosome 1, 2, 4, 7, 8 and 12 are not shown because QTL were not detected on them.