高温胁迫对葡萄幼树生理指标和超显微结构的影响

Effects of Heat Stress on Physiological Indexes and Ultrastructure of Grapevines

【目的】研究高温胁迫对葡萄生理指标和超显微结构的影响,探讨葡萄在高温胁迫下的生理响应机制。【方法】以一年生欧亚种‘赤霞珠’和刺葡萄‘君子1号’扦插苗为试验材料,在35℃、40℃和45℃植物培养箱中连续处理48 h,以25℃培养的植株作为对照,检测葡萄叶片的相对电导率、相对含水量、叶绿素总量、抗氧化酶活性、丙二醛(MDA)/超氧阴离子/过氧化氢含量、叶绿素荧光参数和光合参数,并通过扫描电镜和透射电镜对气孔形态和叶绿体结构进行观察。【结果】在35℃和40℃高温处理后,‘赤霞珠’和‘君子1号’的植株形态、相对电导率、相对含水量、叶绿素总量、叶绿素荧光参数均无显著变化,但净光合速率(Pn)、蒸腾速率(Tr)和气孔导度(Gs)显著降低;在45℃高温处理后,‘赤霞珠’和‘君子1号’号均出现胁迫症状,相对电导率显著增加,相对含水量、叶绿素总量、Fv/Fm、ΦPSⅡ、Pn、Tr和Gs显著降低,且‘君子1号’各参数的变化幅度大于‘赤霞珠’。随着处理温度的升高,葡萄叶片中丙二醛/超氧阴离子/过氧化氢含量、超氧化物歧化酶(SOD)和过氧化物酶(POD)活性不断增加,而过氧化氢酶(CAT)在中度高温胁迫下活性最高,且‘赤霞珠’SOD和CAT活性的增加幅度大于‘君子1号’。扫描电镜观察发现,常温下‘赤霞珠’的气孔密度大于‘君子1号’,在高温处理后葡萄叶片的气孔开张度减小,但气孔大小无显著变化。用透射电镜观察发现,高温处理使叶绿体的体积变大、形状变圆,叶绿体膜解体,出现大量巨型淀粉粒,并在‘君子1号’叶绿体上观察到大量嗜锇颗粒。【结论】‘赤霞珠’的气孔密度大,叶绿体结构稳定,高温处理后SOD和CAT活性大幅增加是其耐热性高的重要原因。

【Objective】 The objective of this research was to study the effects of heat stress on physiological indexes and ultrastructure of grapevines, and to explore the physiological response mechanism of grapevines to heat stress. 【Method】 One-year cutting seedlings of Vitis vinifera L. cv. Cabernet Sauvignon and Vitis davidii Foex. cv. Junzi 1 were used as test materials, which were treated at 35℃, 40℃ and 45℃ for 48 h, with the plants at 25℃ as the control. Relative electrolyte leakage, relative water content, total chlorophyll content, antioxidant enzyme activity, malondialdehyde/super oxygen anion/hydrogen peroxide content, chlorophyll fluorescence and photosynthetic parameters of grape leaves were detected. By the scanning electron microscopy(SEM) and transmission electron microscopy(TEM), stomatal morphology and chloroplast ultrastructure were observed. 【Result】 After heat treatment at 35℃ and 40℃, the plant morphology, relative electrolyte leakage, relative water content, total chlorophyll content and chlorophyll fluorescence of Cabernet Sauvignon and Junzi 1 showed no significant changes, but net photosynthetic rate(Pn), transpiration rate(Tr) and stomatal conductance(Gs) were significantly reduced. After heat treatment at 45℃, Cabernet Sauvignon and Junzi 1 appeared stress symptoms, with relative electrolyte leakage increasing, and relative water content, total chlorophyll content, Fv/Fm, ΦPSⅡ, Pn, Tr and Gs decreasing. The change range of each parameter in Junzi 1 was greater than that in Cabernet Sauvignon. With the increase of temperature, malondialdehyde/superoxide anion/hydrogen peroxide content, SOD and POD activities in grape leaves increased continuously, while CAT activity was the highest under moderate heat stress. The increase of SOD and CAT activities in Cabernet Sauvignon leaves was greater than that in Junzi 1. By SEM, it was found that at room temperature, the stomatal density of Cabernet Sauvignon was higher than that of Junzi 1;after heat treatment, the stomatal opening of grape leaves decreased, but the stomatal size did not change significantly. By TEM, it was found that after heat treatment, the chloroplast became large and round;the chloroplast membrane disintegrated;many giant starch grains appeared;a large number of plastoglobules were observed in the chloroplast of Junzi 1. 【Conclusion】In Cabernet Sauvignon, stomatal density was high, chloroplast structure was stable, and SOD and CAT activities highly increased after heat treatment, which were the important reasons for its high heat resistance.