Abstract: 【Objective】The objective of this study is to provide useful information for wheat breeding program, a total of 306 wheat cultivars or advanced lines from the Yellow and Huai valleys of China were used to identify LOX (Lipoxygenase) activity and allelic variations of LOX genes in this study.【Method】 Spectrophotometer and microplate were used to measure the LOX activity. The molecular marker Xwmc312 on chromosome 1AL and the functionalmarkers LOX16 and LOX18 on chromosome 4BSwere employed to identify the polymorphism of the LOX genes in Chinese wheat cultivars or advanced lines surveyed by combinations of PCR (Polymerase Chain Reaction) amplification and agarose and electrophoresis gels. 【Result】 The phenotyping results showed that the averaged LOX activity was 65.73 AU·min^-1·g^-1 and the standard deviation (SD) was 13.54 in the wheat cultivars surveyed from the Yellow and Huai valleys, and it ranged from 27.09 to 99.55 AU·min^-1·g^-1 and its coefficient of variation (CV) was 20.6%. In the wheat cultivars surveyed from the Yellow and Huai valleys, LOX activities of 7 wheat cultivars were less than 40 AU·min^-1·g^-1 and LOX activities of 8 wheat cultivars exceeded 90 AU·min^-1·g^-1. These cultivars could provide very important germplasms for improvement of LOX activities of currently popular wheat in wheat breeding program. Genotyping results indicated that three alleles Xwmc312₂₂₇, Xwmc312₂₃₅ and Xwmc312₂₄₇ were found at the QLpx.caas-1AL locus in these wheat varieties with 30.4%, 19.0% and 50.6%, respectively. At TaLOX-B1 locus, two alleles TaLOX-B1a and TaLOX-B1b were identified by the functionalmarkers LOX16 and LOX18 with 28.8% and 71.3%, respectively, in the bread wheat cultivars surveyed. Six allele combinations of LOX genes, i.e., TaLOX-B1a/Xwmc312₂₂₇, TaLOX-B1a/Xwmc312₂₃₅, TaLOX-B1a/Xwmc312₂₄₇, TaLOX-B1b/Xwmc312₂₂₇, TaLOX-B1b/Xwmc312₂₃₅ and TaLOX-B1b/Xwmc312₂₄₇, were found, with 7.2%, 9.5%, 12.1%, 23.2%, 9.5% and 38.6%, respectively, in the bread wheat cultivars surveyed.Analysis of association of LOX alleles and LOX activity indicated that the average of LOX activity of wheat cultivars with Xwmc312₂₃₅ is significantly higher than those of cultivars with Xwmc312₂₂₇ and Xwmc312₂₄₇, and the average of LOX activity of cultivars with TaLOX-B1a is significantly higher than those of cultivars with TaLOX-B1b (P＜0.05). Moreover, analysis of association of LOX allele combination and LOX activity showed that the LOX activity (76.803 AU·min^-1·g^-1) of the cultivars with TaLOX-B1a/Xwmc312₂₃₅ is significantly higher than those of other five LOX allele combinations, whereas the LOX activity (62.45 AU·min^-1·g^-1) of the cultivars with TaLOX-B1b/Xwmc312₂₂₇ genotype is significantly lower than those of other five combinations. 【Conclusion】It was concluded that LOX activities of most of the wheat cultivars from the Yellow and Huai valleys were middle type and the wheat cultivars with extremely low (less than 40 AU·min^-1·g^-1 ) or high (more than 90 AU·min^-1·g^-1 ) LOX activities were very scarce in the Yellow and Huai wheat regions. Amongst 6 different combinations of LOX genes, wheat cultivars with TaLOX-B1a/Xwmc312₂₃₅possessed relatively the highest LOX activity and wheat cultivars with TaLOX-B1b/Xwmc312₂₂₇ possessed relatively the lowest LOX activity in the Yellow and Huai wheat regions (P＜0.05). These results offered important gene germplasms for improvement of LOX activities of bread wheat in wheat breeding program. This study could also provide important information for wheat quality improvement in China.

Key words: bread wheat, flour color, lipoxygenase, allelic variation