干旱胁迫对甘蔗根系碳氮代谢的影响

Effects of drought stress on carbon and nitrogen metabolism of sugarcane roots

【目的】探究甘蔗根系响应水分变化的碳氮代谢生理应答机理,为后续研究甘蔗的抗旱性和高产栽培研究提供参考。【方法】以新台糖22号为试验材料,在大棚中采用桶栽方式,模拟自然干旱胁迫过程,在处理开始后第0、1、3、5、7、9、11、15、19和25 d采样并测定土壤水含量及甘蔗根系的水含量、碳水化合物和氮同化产物含量及关键酶活性,分析各项指标干旱胁迫后的动态变化趋势。【结果】干旱胁迫下,甘蔗根系水含量逐渐降低,至干旱胁迫第25 d时,根系水含量降至19.42%,较第0 d(75.64%)时降低56.22%(绝对值)。随着干旱胁迫时间的延长,氮代谢中脯氨酸和游离氨基酸含量随着干旱程度的加重而逐渐增加,于干旱处理第25 d时均达最高值,分别为85.69和20.08 mg/gFW,而硝酸还原酶活性变化呈前期降低、中期升高、后期又逐渐下降的波动变化趋势。碳代谢中的可溶性糖含量波动升高,干旱胁迫第19 d时达最高值(4.47 mg/gFW),干旱胁迫第25 d时出现回落;淀粉含量与可溶性糖含量变化趋势相反,干旱胁迫第25 d时淀粉含量降至最低值(0.55 mg/gFW),但淀粉酶活性逐渐升至最高值[18.15 mg/(gFW·min)]。【结论】干旱胁迫下甘蔗根系通过调节碳氮代谢关键酶活性、碳水化合物和氮同化物含量从而避免干旱对根系的伤害,保障甘蔗正常生长发育,但根系只能在一定时间范围内抵御干旱胁迫造成的伤害,因此需要在干旱初期阶段做好防范措施。

【Objective】The physiological response mechanism of carbon and nitrogen metabolism in sugarcane root under drought stress were explored with the aim of providing references for further study on drought tolerance of sugarcane root and high yield cultivation.【Method】The ROC22 sugarcane root as materials,by simulating natural drought stress on sugarcane planted in soil pails under the greenhouse,sugarcane were sampled on 0,1,3,5,7,9,11,15,19 and 25 d after treatment,physiological indexes were measured under drought stress,including soil water content,water content of sugarcane roots,carbohydrate content,nitrogen assimilation products content and key enzyme activities.The dynamic change of each index after drought stress was analyzed.【Result】Under drought stress,the water content of root were gradually decreased,after 25 d of treatment,the water content of root decreased to 19.42%,compared with 0 d(75.64%),the water content of root decreased by 56.22%(absolute value).With the extension of drought stress time,the contents of proline and free amino acid in nitrogen metabolism increased as the drought level strengthened.After 25 d of drought,the maximum content of proline and free amino acid in nitrogen metabolism were 85.69 and 20.08 mg/gFW respectively.The activity of nitrate reductase presented wave-tendency,decreased in the early stage,increased in the middle stage,and decreased gradually in the later stage.Soluble sugar content in carbon metabolism rose in volatility,after 19 d,the soluble sugar content in carbon metabolism reached its maximum value of 4.47 mg/gFW and then declined since day 25.The trend of starch content was contrary to soluble sugar content,starch content reached its minimum value of 0.55 mg/gFW on day 25 and amylase activity reached its maximum value of 18.15 mg/(gFW·min).【Conclusion】Under drought stress,sugarcane root system can avoid the damage of drought by regulating the key enzyme activity of carbon and nitrogen metabolism,carbohydrate and nitrogen assimilate content,thus ensuring the growth and development of sugarcane.But root can only resist from the harm caused by drought within a certain period,the countermeasures should be conducted at the early stage of drought stress.