Effects of Moisture Content on Root Vigor and the Expression of Aquaporin-related Genes in Rice Seedlings Under Low Temperature Stress

doi:10.16819/j.1001-7216.2022.210805

Abstract

Abstract:

Abstract：【Objective】The purpose of this study is to explore the effects of moisture content or humidity on root vigor and water transport of rice seedlings under low temperature stress. 【Method】Two rice cultivars (Jiaxian 7 and Fu 8329) with different chilling tolerance were used as materials. Experiment I (humidity 30%, 60% and 90%) and experiment Ⅱ (quick rewarming experiment) were carried out. 【Result】Compared with lower humidity (30%), higher humidity (60% and 90%) could effectively increase the root vigor, ensure the survival rate of rice seedlings and alleviate the chilling injury. The expression level of OsPIP2;5 and OsPIP2;6 were closely related to root vigor, which had a significant regulatory effect on cold tolerance of rice. Compared with normal rewarming treatment (CK), the water content and root vigor of rice seedlings were decreased after quick rewarming treatment. The survival rate in CK was significantly higher than in the quick rewarming experiment. 【Conclusion】 Low temperature stress affects the growth and development of rice seedlings. After chilling injury, high humidity can alleviate the damage and ensure the rice survival rate. Humidity environment after low temperature stress significantly influenced the water content, root vigor and the expression levels of genes related to aquaporin. The expression levels of OsPIP2;5 and OsPIP2;6 were positively correlated with root vigor, and played an important role in resistance to cold injury of rice seedlings. Therefore, compared with large-scale irrigation in the field after low temperature stress, the slow soil temperature rise had less effect on root vigor and can help rice seedlings to restore their life activities.

Key words: rice, low temperature stress, gene expression, root vigor, aquaporin, moisture content

摘要：

【目的】为了探究低温冷害胁迫后水分/湿度对水稻幼苗根系活力和水分运输等的影响，【方法】以具有低温耐性差异的嘉籼7号和辐8329两个水稻品种为研究材料进行低温胁迫处理后，在进行实验Ⅰ（不同湿度梯度，正常温度培养条件下）和实验Ⅱ（快速回温处理实验，以正常温度恢复为对照）。【结果】实验Ⅰ结果表明，与较低湿度（30%）相比，较高的湿度（60%和90%）可以提高根系活力，有效保证水稻幼苗的存活率并缓解其遭受的低温冷害。水孔蛋白基因OsPIP2;5和OsPIP2;6的表达水平与根系活力密切相关，对水稻的抗寒和低温耐性具有显著的调控作用。实验Ⅱ结果表明，与对照组（CK）相比，快速回温处理后水稻幼苗的含水量和根系活力显著降低;且正常自然恢复状态下，两个水稻品种的存活率明显高于快速回温组幼苗。【结论】低温胁迫显著影响水稻幼苗的生长发育过程。较高的湿度环境有助于缓解幼苗的低温冷害损伤，保证存活率。同时，低温胁迫后的外界环境湿度对水稻幼苗的含水量、根系活力和水孔蛋白相关基因表达有显著影响，其中OsPIP2;5和OsPIP2;6的表达水平与根系活力正相关，在水稻幼苗抵御外界低温冷害过程中起重要作用。因此，与低温胁迫后田间大量灌溉相比，正常温度下土壤缓慢的温度上升对幼苗的根系活力影响较小，有助于其在低温冷害后恢复生命活动。

关键词: 水稻, 低温胁迫, 基因表达, 根系活力, 水孔蛋白, 水分含量

HUANG Qina, JIANG Su, WANG Limin, ZHANG Yan, YU Linfei, LI Chunfu, DING Liqun, SHAO Guosheng. Effects of Moisture Content on Root Vigor and the Expression of Aquaporin-related Genes in Rice Seedlings Under Low Temperature Stress[J]. Chinese Journal OF Rice Science, 2022, 36(4): 367-376.

黄奇娜, 江苏, 汪利民, 张燕, 俞林飞, 李春福, 丁利群, 邵国胜. 低温胁迫后水分对水稻幼苗根系活力和水孔蛋白相关基因表达的影响[J]. 中国水稻科学, 2022, 36(4): 367-376.

Figures/Tables 7

Fig. 1. Phenotype of Jiaxian 7 and Fu 8329 after 3 days of low temperature treatment. A, Before low temperature treatment; B, 1 d of low temperature treatment; C, 3 d of low temperature treatment.

Fig. 2. Phenotype, sand temperature and survival rate of Jiaxian 7 and Fu 8329 under different humidity after low temperature stress. A, Phenotype of Jiaxian 7 under different humidity conditions(30%，60%，90%); B, Phenotype of Fu 8329 under different humidity conditions; C, Sand temperature of Jiaxian 7 and Fu 8329; D, Survival rate of Jiaxian 7 and Fu 8329. Data were means ± standard deviation (SD) from three replicated experiments (n = 3). Different lowercase letters represent significant differences (P < 0.05).

Table 1. Root vigor of Jiaxian 7 and Fu 8329 exposed to different humidity for 5 d. mg/(g·h)

品种 Variety	低湿度 Low humidity	中湿度 Medium humidity	高湿度 High humidity
嘉籼7号Jiaxian 7	129.75 ± 5.34 d	170.92 ± 2.60 b	97.48 ± 3.36 e
辐8329 Fu 8329	144.84 ± 1.78 c	404.19 ± 18.53 a	161.63 ± 2.88 b

Fig. 3. Effect of humidity treatments after chilling stress on relative expression levels of aquaporin-related genes in roots of Jiaxian 7 and Fu 8329. Data were means ± standard deviation (SD) from three replicated experiments (n = 3)（t-test）; **, Significant at P < 0.01.

Fig. 4. Phenotype, sand temperature and survival rate of Jiaxian 7 and Fu 8329 after quick rewarming. A, Controls; B, Quick rewarming after 5 h of treatment; C, Phenotype of Jiaxian 7 and Fu 8329 with water change test after 3 d; D, Sand temperature of Jiaxian 7 and Fu 8329; E, Survival rate. Data were means ±SD (n = 3). Different lowercase letters represent significant differences (P < 0.05).

Fig. 5. Moisture content and water content in shoots and roots of Jiaxian 7 and Fu 8329 after 0, 4 and 8 h of treatment. CK, Control; QR, Quick rewarming. Data were means ± standard deviation (SD) from three replicated experiments (n = 3). Different lowercase letters above the error bars represented significant differences (P < 0.05). A, Moisture content of shoots; B, Moisture content of roots; C, Water content (%) of shoots; D, Water content (%) of roots.

Table 2. Effect of quick rewarming and normal rewarming on root vigor of chilled Jiaxian 7 and Fu 8329.

品种 Variety	处理后0 h 0 h after treatment/ (mg·g⁻¹·h⁻¹)		处理后3 d Three days after treatment/ (mg·g⁻¹·h⁻¹)
品种 Variety	对照组 CK	快速回温组 Quick rewarming	对照组 CK	快速回温组 Quick rewarming
嘉籼7号 Jiaxian 7	12.68 ± 0.66 b	25.40 ± 5.59 a	181.66 ± 1.85 b	43.12 ± 2.52 d
辐8329 Fu 8329	9.74 ± 1.49 b	13.17 ± 1.03 b	308.67 ± 5.95 a	87.40 ± 2.97 c

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