Effect of Poly(γ-glutamic acid) on the Physiological Responses and Calcium Signaling of Rape Seedlings (Brassica napus L.) under Cold Stress

• Published in: Journal of agricultural and food chemistry Vol. 63; no. 48; pp. 10399 - 10406
• Main Authors: Lei, Peng, Xu, Zongqi, Ding, Yan, Tang, Bao, Zhang, Yunxia, Li, Huashan, Feng, Xiaohai, Xu, Hong
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 09.12.2015
• Subjects: Brassica napus; Brassica napus - genetics; Brassica napus - metabolism; calcium; Calcium - metabolism; calcium signaling; Catalase - metabolism; chlorophyll; Chlorophyll - metabolism; cold; cold stress; Cold Temperature; crops; cryoprotectants; cytoplasm; enzyme activity; growth retardation; hydroponics; malondialdehyde; Malondialdehyde - metabolism; physiological response; plant growth; plant growth substances; Plant Leaves - metabolism; Plant Proteins - metabolism; polyglutamic acid; Polyglutamic Acid - analogs & derivatives; proline; protein kinases; seedlings; Seedlings - genetics; Seedlings - growth & development; Seedlings - metabolism; Signal Transduction; Superoxide Dismutase - metabolism; weather; proline; Ca2+ fluctuation; cold stress; antioxidant enzymes; Ca2+/CPKs signal pathway; poly(γ-glutamic acid)
• ISSN: 0021-8561; 1520-5118; 1520-5118
• DOI: 10.1021/acs.jafc.5b04523

Cold stress adversely affects plant growth and development. Poly­(γ-glutamic acid) (γ-PGA) is a potential plant growth regulator that may be an effective cryoprotectant that prevents crops from damage during cold weather. In this study, the effects of γ-PGA on the physiological responses of rape seedlings subject to cold stress were investigated using hydroponic experiments. We determined that the malondialdehyde content was decreased by 33.4% and the proline content was increased by 62.5% by γ-PGA after 144 h under cold stress. Antioxidant enzymes activities were also evidently enhanced after treatment with γ-PGA. These responses counteracted increases in the fresh weight and chlorophyll content of rape seedlings, which increased by 24.5 and 50.9%, respectively, after 144 h, which meant that growth inhibition caused by cold was mitigated by γ-PGA. Our results also showed that γ-PGA also regulated Ca2+ concentrations in the cytoplasm and calcium-dependent protein kinases, which are associated with cold resistance. In conclusion, we suggest that the Ca2+/CPKs signal pathway is involved in the γ-PGA-mediated enhancement of cold resistance in rape seedlings.