Abstract

The effects of a long-term (6-day) exposure to low positive temperature (4°С, LT treatment) and short-term (3 h per a day for 6 days) daily temperature drops to 4°С (DROP treatment) on leaf respiration in winter wheat (Triticum aestivum L., var. Moskovskaya 39) were studied under controlled conditions. In the case of the LT treatment, the respiration rate in the darkness (R_d) increased by 36%, while the DROP treatment only resulted in a tendency to such an increase. The influence of both DROP and LT treatments on the respiration rate in the light (R_l) and temperature sensitivity of R_d and R_l was insignificant. In contrast to the DROP treatment, the LT treatment increased the level of light-induced inhibition of plant respiration. In both LT- and DROP-treated plants, the rate of gross photosynthesis (A_g) measured at 12°С increased by 23 and 54%, respectively, as compared to the control plants. The DROP treatment did not affect the R_d/A_g and R_l/A_g ratios in plant leaves. The R_d/A_g value in LT-treated plants measured at 22°С was higher than in control plants, while the R_l/A_g value measured at 12°С was lower than in the control. The DROP treatment did not affect the sensitivity of respiration to salicylhydroxamic acid (SHAM), an inhibitor of the alternative respiratory pathway. The LT treatment increased the share of a SHAM-sensitive respiration in the total respiration of plant leaves by 25% on average, which indirectly indicates the activation of an alternative pathway of the electron transfer in the respiratory chain. Thus, a long-term continuous exposure of winter wheat seedlings to low positive temperatures provided a modifying effect on respiration manifested via changes in the respiratory rate, activity of the SHAM-sensitive respiration, and the ratio between respiration and gross photosynthesis. In the case of a short-term daily exposure to low temperature high respiration stability was observed.

中文翻译：

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冬小麦幼苗呼吸对长期冷暴露和短期日温度下降的响应

摘要

长期（6天）暴露于低正温度（4°С，LT治疗）和短期（每天3小时，每天6天）每天温度降至4°С（DROP治疗）的影响在控制条件下研究了冬小麦（Triticum aestivum L.，var。Moskovskaya 39）叶片呼吸的变化。在LT处理的情况下，黑暗中的呼吸速率（R _d）增加了36％，而DROP处理仅导致这种增加的趋势。DROP和LT处理对光呼吸速率（R _l）和R _d和R _l的温度敏感性的影响是微不足道的。与DROP处理相反，LT处理增加了光诱导的植物呼吸抑制水平。与对照植物相比，在LT和DROP处理的植物中，在12°C下测得的总光合作用速率（A _g）分别增加了23％和54％。DROP处理不影响植物叶片中的R _d / A _g和R _l / A _g比。在22°С下测得的LT处理植物的R _d / A _g值高于对照植物，而R _l / A _g在12°C下测得的值低于对照。DROP处理不会影响呼吸对水杨基异羟肟酸（SHAM）的敏感性，后者是另一种呼吸途径的抑制剂。LT处理使SHAM敏感呼吸在植物叶片总呼吸中的份额平均增加了25％，这间接表明激活了呼吸链中电子转移的另一种途径。因此，冬小麦幼苗长期连续暴露在低的正温度下，对呼吸的调节作用是通过呼吸速率，SHAM敏感呼吸的活性以及呼吸与总光合作用之比的变化表现出来的。在短期短期每天暴露于低温的情况下，观察到高呼吸稳定性。