QTL analysis for grain quality traits in 2 BC2F2 populations derived from crosses between Oryza sativa cv Swarna and 2 accessions of O. nivara.
The appearance and cooking quality of rice determine its acceptability and price to a large extent. Quantitative trait loci (QTLs) for 12 grain quality traits were mapped in 2 mapping populations derived from Oryza sativa cv Swarna × O. nivara. The BC(2)F(2) population of the cross Swarna × O. nivara IRGC81848 (population 1) was evaluated during 2005 and that from Swarna × O. nivara IRGC81832 (population 2) was evaluated during 2006. Linkage maps were constructed using 100 simple sequence repeat (SSR) markers in population 1 and 75 SSR markers in population 2. In all, 21 QTLs were identified in population 1 (43% from O. nivara) and 37 in population 2 (38% QTLs from O. nivara). The location of O. nivara-derived QTLs mp1.2 for milling percent, kw6.1 for kernel width, and klac12.1 for kernel length after cooking coincided in the 2 populations and appear to be useful for Marker Assisted Selection (MAS). Four QTLs for milling percent, 1 QTL each for amylose content, water uptake, elongation ratio, 2 QTLs for kernel width, and 3 QTLs for gel consistency, each explained more than 20% phenotypic variance. Three QTL clusters for grain quality traits were close to the genes/QTLs for shattering and seed dormancy. QTLs for 4 quality traits were associated with 5 of the 7 major yield QTLs reported in the same 2 mapping populations. Useful introgression lines have been developed for several agronomic traits. It emerges that 40% O. nivara alleles were trait enhancing in both populations, and QTLs for grain quality overlapped with yield meta-QTLs and QTLs for dormancy and seed shattering.
Directorate of Rice Research, Rajendranagar, Hyderabad 500030, Andhra Pradesh, India. m.swamy@irri.org
B P Mallikarjuna
BP
Swamy
K
K
Kaladhar
N
N
Shobha Rani
G S V
GS
Prasad
B C
BC
Viraktamath
G Ashok
GA
Reddy
N
N
Sarla
D000483:Alleles; D000688:Amylose / Q000378:metabolism; D002874:Chromosome Mapping; D003296:Cooking; D002523:Edible Grain / Q000033:anatomy & histology / Q000235:genetics* / Q000378:metabolism; D024861:Genetic Enhancement; D006824:Hybridization, Genetic; D018895:Microsatellite Repeats / Q000235:genetics; D012275:Oryza / Q000033:anatomy & histology / Q000235:genetics* / Q000378:metabolism; D010641:Phenotype; D040641:Quantitative Trait Loci
D000688:Amylose