Grain-specific reduction in lipoxygenase activity improves flour color quality and seed longevity in common wheat

• Published in: Molecular breeding 2015-07, Vol.35 (7), p.1-18, Article 150
• Main Authors: Dong, Zhenying, Feng, Bo, Liang, Hui, Rong, Chaowu, Zhang, Kunpu, Cao, Xuemin, Qin, Huanju, Liu, Xin, Wang, Tao, Wang, Daowen
• Format: Article
• Language: English
• Subjects: Aging; Aging (artificial); Biomedical and Life Sciences; Biotechnology; Bombardment; color; Endosperm; Fatty acids; Flour; genetically modified organisms; Genomes; Germination; Grain; Harvesting; homozygosity; humidity; leaves; Levels; Life Sciences; Lipoxygenase; Liquid oxygen; Longevity; Molecular biology; Oxidation; Particle bombardment; Plant biology; Plant Genetics and Genomics; Plant Pathology; Plant Physiology; Plant Sciences; Polyunsaturated fatty acids; Quality management; Reduction; RNA interference; RNA-mediated interference; seed development; Seeds; stored grain; transgenes; Triticum aestivum; Wheat
• ISSN: 1380-3743; 1572-9788
• DOI: 10.1007/s11032-015-0347-9

In higher plants, lipoxygenases (LOXs) catalyze the oxidation of polyunsaturated fatty acids and can accumulate to relatively high levels in the seeds. However, high LOX activity has often been found associated with harmful effects on the quality attributes and the longevity of harvested seeds. Here, we report the development and characterization of three homozygous T₅ transgenic lines (designated as LOXᴿᴺᴬⁱ-4, 7 and 9, respectively) with LOX activity specifically reduced in the grains of common wheat. An RNAi hairpin directed under an endosperm-specific promoter was introduced into the genome of the elite wheat variety Longchun 23 using particle bombardment. Each transgenic line (LOXᴿᴺᴬⁱ-4, 7 or 9) derived from separate integration event, which carried more than 20 copies of the transgene. The three LOXᴿᴺᴬⁱ lines and wild-type (WT) Longchun 23 showed a similar level of LOX transcripts in the flag leaves. However, relative to WT control, LOXᴿᴺᴬⁱ-4, 7 and 9 exhibited drastic decreases in the level of LOX transcripts during grain development compared with WT control. The LOX activity levels in the harvested grains of the three transgenic lines were significantly lower than that of WT control under either normal conditions or artificial aging (AA, stored at 40 °C and 85 % humidity for 6 or 9 days) treatment. The whiteness values of the flour samples from LOXᴿᴺᴬⁱ-4, 7 and 9 were generally and significantly higher than those of WT control regardless of the grains were stored under normal or AA conditions. Furthermore, the germination rates of LOXᴿᴺᴬⁱ-4, 7 and 9 were substantially higher than those of WT control under AA treatment. Our data demonstrate that grain-specific reduction in LOX activity by RNAi may represent a generally applicable approach for improving the quality traits and longevity of crop seeds.