Effects of abiotic stress on anthocyanin accumulation and grain weight in purple wheat

This study explored the effects of abiotic stress on anthocyanin accumulation and grain weight of purple wheat (Triticum aestivum L. cv. Guizi 1). Plants were treated with five abiotic stress factors at different developmental periods of the grain, then mature grains were analysed for anthocyanin content and 1000-grain weight (TGW). Stresses included temperature (cold and heat), light (shading irradiance and continuous irradiance), drought (20 and 40mm PEG 6000), salinity (100 and 200mm NaCl), and wounding (four types). Of all treatments, 25% tended to increase both anthocyanin content and TGW, although only 5% reached a significant level, 27.5% decreased both, 40% increased anthocyanins but decreased TGW, and 7.5% increased TGW but decreased anthocyanins. Heat stress tended to increase anthocyanin content and decrease TGW, whereas cold stress increased anthocyanins only at 15 days post-anthesis (DPA) and decreased both traits at other times. Shading irradiance decreased anthocyanins but had little effect on TGW. Continuous irradiance increased anthocyanins and TGW at 35 DPA but decreased both at 10 DPA. The lower levels of drought (20mm PEG 6000) and salinity (100mm NaCl) stress tended to increase anthocyanins and decrease TGW; however, the effects of 40mm PEG 6000 and 200mm NaCl were different, and were period-dependent. The four types of wounds increased anthocyanins and TGW at 30 DPA, but their individual effects were different in the other four periods. The results quantified the effects of five abiotic stress factors on anthocyanin accumulation and grain weight, and provide the foundation for further study of defence-responsive molecular mechanisms of abiotic stress in purple wheat.