摘要: 含水量是影响种子超低温保存效果的关键因素，而其作用机制尚不完全清楚。为探讨含水量对种子超低温保存生活力的影响途径，该研究以八棱海棠种子为材料，通过硅胶干燥法获得不同含水量的种子，测定超低温保存后种子生活力、糖含量及相关酶指标的变化并分析相关性。结果表明：（1）超低温保存15 d 后，不同含水量种子生活力不同，随着种子含水量的降低，种子生活力呈现先升高后降低的趋势，含水量为 9.02%的八棱海棠种子生活力最高，为 53.33%；超低温保存 120 d 后，种子生活力随着含水量下降一直升高，含水量为 6.40%生活力最高，为27.78%。表明八棱海棠种子含水量对超低温保存后的生活力有明显影响，但受液氮保存时间影响，随着液氮保存时间的延长，最适含水量降低。（2）相关性分析显示，含水量与生活力显著负相关，含水量和生活力均与蔗糖和果糖含量相关，酸性转化酶与含水量、生活力、蔗糖和果糖均相关，果糖激酶与生活力相关，表明种子含水量通过影响酸性转化酶活性而影响蔗糖和果糖含量，进而影响蔗糖代谢，响应低温和脱水胁迫，最终导致生活力差异。种子生活力还受到介导果糖激酶的果糖代谢影响。此外，海藻糖也是种子应对脱水和低温胁迫重要的调节物质之一。综上所述，八棱海棠种子不同含水量对其超低温保存后生活力有明显影响，与蔗糖和果糖代谢差异有关。该研究为种子超低温保存机制揭示提供了理论参考。
Abstract: Water content is a key factor influencing the seed cryopreservation, but its effecting mechanism is not fully understood. In order to provide theoretical basis for further improving the seeds viability after cryopreservation, the effect and way of water content on the viability of seed cryopreservation were explored. Malus � robusta seeds with different water contents were obtained by silica gel. The seed viability, sugar content and related enzyme indexes before and after cryopreservation were measured and correlation analysis were done. The results were as follows: (1) After 15 days of cryopreservation, the viability of seeds with different water contents was different, and the viability of seeds showed a trend of increasing and then decreasing as the water content of seeds decreased, and the seeds with 9.02% water content had the highest germination rate, at 53.33%. But after 120 days of cryopreservation, the viability of seeds increased as the water content decreased, and the seeds with 6.40%water content got the highest germination rate, at 27.78%. This indicates that the water content of Malus � robusta seeds has a significant effect on the viability after cryopreservation. It is affected by the storage time in liquid nitrogen, and the optimum water content decreases as the storage time extended in liquid nitrogen. (2) Correlation analysis showed that water content was significantly negatively correlated with viability, both water content and viability were correlated with sucrose and fructose content, acid invertase was correlated with water content, viability, sucrose and fructose, and fructokinase was correlated with viability, suggesting that water content affects the content of sucrose and fructose through effecting the activity of acid converting enzymes, which in turn affects sucrose metabolism to respond to low temperature and dehydration stress, ultimately leading to differences in viability. The seed viability is also affected by fructose metabolism through fructose kinase. Besides, alginate is one of the important regulatory substances of Malus � robusta seeds in response to water and low temperature stresses. In summary, water content has a significant effect on the viability of Malus � robusta seeds cryopreservation through the combined effect of sucrose and fructose metabolism. This study provides a theoretical reference to further explore the cryopreservation mechanism of seed.
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