低温胁迫下枇杷幼果种子膜脂过氧化、保护酶活性及显微结构的变化

Changes in membrane lipid peroxidation,activities of cell defense enzyme and microstructure in the seed of loquat young fruit under chilling stress

枇杷(Eriobotrya japonica)开花结果正值冬季低温期,易受低温影响,因此寒害成为抑制枇杷健康生长、发育的重要因素之一。种子作为产生多种内源激素的中心,其健康程度与枇杷果实正常发育息息相关。该研究以四川省成都市龙泉驿区柏合镇的‘早钟六号’枇杷幼果种子为材料,经不同低温(6、3、0、-3℃)胁迫不同时间(12、24、36、48 h)后,对其相对电导率、丙二醛(MDA)、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和过氧化物酶(POD)的变化进行测定以及细胞解剖结构分析,旨在探究枇杷幼果种子抗寒机制,为提高四川地区枇杷抗寒栽培新技术提供理论和实践依据。结果表明:低温胁迫下,枇杷幼果种子相对电导率及MDA含量随着处理温度的降低整体呈上升趋势;保护酶SOD、CAT活性在低温胁迫前期不同程度升高,至某个低温后呈下降趋势;而POD活性总体呈升-降-升趋势;相对电导率、MDA含量、SOD活性、CAT活性、POD活性的变化临界温度均为6℃,胁迫临界时间分别为12、24、48、36 h,而MDA含量变化临界温度为3℃,胁迫临界时间为36 h;显微结构表明枇杷幼果种子6℃低温开始受冻,最先受冻部位为种皮,其次为种胚真叶原始体或真叶,最后到细胞破裂,说明枇杷幼果种子随着处理温度降低,细胞结构受损越严重。综上,枇杷幼果种子受冻临界温度为6℃,受冻临界时间为12 h。

Loquat （Eriobotrya japonica）Rosaceae loquat （Eriobotrya）,native to subtropical country,is widely popu-lar,because of its high economic value and ornamental value.But loquat flowering period comes in the winter cold, vulnerable to low impact,so chilling inj ury to become one of the important factors inhibiting the loquat healthy and sustainable development.Seeds produce a variety of endogenous hormones as the center of their health degree and is closely related to the normal development of loquat fruit.The ‘Zaozhong’loquat cultivar young fruits were selected to study the cold resistance under different low temperatures （6,3,0,-3 ℃）and different times（12,24,36,48 h）. The relative electric conductivity,MDA,SOD,CAT ,POD and microstructure in seed of loquat young fruit were deter-mined under different low temperature.The results showed that the relative electric conductivity and MDA of seed in-creased under low temperature;The protective activities of SOD and CAT in seed increased at moderate low temper-ature stress,then showed declining trend when the temperature attained certain critical temperature stress;The pro-tective activities of POD had an up-down-up trend;.The critical temperature of relative electric conductivity,SOD, CAT and POD was 6 ℃,the critical times 12,24,48,36 h.But the critical temperature of MDA was 3 ℃,the critical time was 3 6 h.Microstructure diagram showsed that the loquat seeds of young fruit was firstly destroyed 6 ℃,the firstly destroyed part was testa,followed by the leaf primordium or leaf again to change the material composition and content of the cell,and finally to the cell rupture;The microstructure in seed of loquat young fruit was destroyed, comparing with CK,during low temperature.Therefore,the critical low temperature was 6 ℃,the critical time was 1 2 h in seed.This study would provide a theoretical and practical significance to improve the basis for the new cultiva-tion technologies of loquat in Sichuan region.