| 摘要: |
| 【目的】研究低温胁迫下枇杷幼果果肉和种子的生理指标及组织结构的变化规律，探索幼果低温伤害的机制。【方法】以“大五星”枇杷最易受冻的幼果为试材，经不同低温胁迫（12，6，3，0，-3，－6 ℃）处理不同时间（12，24，36，48 h），测定幼果果肉和种子的丙二醛（MDA）含量、相对电导率（REC）、抗氧化酶活性，并研究低温胁迫对其组织结构和低温半致死温度（LT50）的影响。【结果】枇杷幼果果肉、种子的LT50分别是-6.1和-4.9 ℃。果肉、种子分别在0和3 ℃以上的轻度低温胁迫下，超氧化物歧化酶（SOD）、过氧化氢酶（CAT）和过氧化物酶（POD）活性上升，MDA含量和REC均较低；但果肉、种子分别在-3和0 ℃以下重度低温胁迫下，保护酶活性逐渐降低，REC和MDA含量上升。0 ℃时幼果外果皮细胞出现明显破裂和自溶现象，-3 ℃时中果皮（果肉）细胞破裂，果实受低温伤害严重。而种子在3 ℃时种皮细胞出现破裂，0 ℃时种皮与种胚开始分离，种胚细胞自溶明显，低温伤害较重。【结论】轻度低温胁迫时，过氧化酶系统协同作用可有效清除枇杷幼果果肉和种子细胞内的活性氧；重度胁迫时，酶失去保护功能；枇杷幼果中种子耐低温能力最差，3 ℃时即出现低温伤害，其次为外果皮，而果肉耐低温能力则最强。 |
| 关键词: 低温胁迫 枇杷幼果 抗氧化酶 组织结构 |
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| 基金项目:国家农业科技成果转化项目（2010GB2F000408） |
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| Effects of low temperature stress on antioxidant enzyme system and microstructure of young loquat fruit |
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ANG Wei,GONG Ronggao,LIAO Mingan,et al
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| Abstract: |
| 【Objective】The antioxidant enzyme system and microstructure in pulp and seed of young loquat fruit under low temperature stress were investigated to explore the physiology response mechanism of fruit to chilling injury.【Method】‘Dawuxing’ cultivar was treated by different low temperature stresses (12，6,3,0,-3,and －6 ℃) and processing times (12,24,36,and 48 h).Semi-lethal temperatures (LT50),MDA contents,REC,antioxidant enzyme activities and microstructure in pulp and seed of young loquat fruits were measured and analyzed.【Result】The semi-lethal temperatures of pulp and seed were -6.1 and -4.9 ℃,respectively.The activities of SOD,CAT and POD in pulp and seed increased at temperatures of 3 and 0 ℃,while the relative electric conductivity (REC) and MDA content were at low levels.But the activities of SOD,CAT and POD decreased gradually at temperatures of -3 and <0 ℃,while REC and MDA increased.Microstructure diagram showed that the loquat exocarp of young fruits broken at 0 ℃,mesocarp (pulp) broken at -3 ℃ and the fruit had remarkable freeze injury.The seed of young fruit was firstly destroyed at 3 ℃,testa and embryo began to separate at 0 ℃,embryo cell autolyzed clearly,and chilling injury was heavy.【Conclusion】The antioxidant enzyme activities increased at moderate low temperature stress,whereas they declined significantly at certain critical temperature stress.Mesocarp of young loquat fruit showed the highest cold resistance,followed by exocarp and seed. |
| Key words: low temperature stress young loquat fruit antioxidant enzyme microstructure |
