QTLs for Shoot Length and Chlorophyll Content of Rice Seedlings Grown under Low-Temperature Conditions, using a Cross between Indica and Japonica Cultivars

Abstract

Quantitative trait loci (QTLs) affecting the shoot length and chlorophyll content of seedlings grown at a low temperature (16ºC) for 4 weeks were analyzed using inbred lines derived from a cross between an indica rice cultivar, Habataki, and a japonica rice cultivar, Arroz da Terra. Culm length of the inbred lines, measured at the harvesting stage, was also analyzed. The QTLs linked to increased shoot length (qSL1) and culm length (qCL1) on the Arroz da Terra allele were detected in the same region of chromosome 1, where the gibberellin 20 oxidase-2 gene (identical to Semi Dwarf1: SD1) located. Other QTLs (qSL3 and qSL8) that were linked to increased shoot length on Arroz da Terra and Habataki alleles, but had no effects on the culm length, were detected on chromosomes 3 and 8, respectively. The alleles of qSL3 and qSL8 might improve early shoot growth without increasing the risk of lodging caused by a long culm length. A novel QTL (qCC1) linked to increased chlorophyll content of seedlings grown at low temperatures through the effect of an Arroz da Terra allele was detected on chromosome 1, but it differed in position from the QTLs for shoot length.