Response ofRice Starch Synthesis to Night Temperature Changes

doi:10.16819/j.1001-7216.2020.0701

Abstract

Abstract:

【Objective】To clarify the effect of night temperature changes on rice starch accumulation, and to explore circadian changes ofphysiological characteristics of rice amylose/amylopectin formation atvarious night temperatures.【Method】High-quality japonica rice ‘Zhehexiang 2’ was subjected to three night temperature gradients of 31℃/20℃ (LT), 31℃/24℃ (NT), and 31℃/28℃ (HT) at the beginning of grain ripening stage, and the amylose and amylopectin contents, the key enzyme activities involvedin amylose and amylopectin formation and the expression of related genes were measured at noon and midnight. 【Result】The results showed that1) compared with NT, LT and HT treatments significantly reduced grain weight and starch accumulation, LT and HT both reduced amylopectin content and increased amylose content, meanwhile the effect of HT was greater than LT. LT and HT treatments decreased grain pasting temperature and gel consistency, and hada significantinfluence on branched chain length. 2) The net photosynthetic rate of leaves under LT and HT presented no significant difference compared to NT, but LT and HT significantly reduced the accumulation of non-structural carbohydrates, meanwhile down-regulated the expression level of sucrose transporter genes OsSUT1, OsSUT2, and OsSUT4 both at noon and midnight.3) LT and HT treatment reduced sucrose hydrolysis-related enzyme activities, meanwhile promoted starch hydrolase activities, resulting in increased soluble sugar contents,sugar utilization in grain was blocked.4) Compared with NT, the adenosine diphosphate glucose content showed a downward tendency during the day and a rising trend at night under the treatment of LT and HT,which presented that the accumulation and utilization of adenosine diphosphate glucose were inhibited. And the granules bound starch synthetaseactivity weresignificantly reduced under LT and HT compared to NT with the prolongation of the treatment, and the enzyme activity at daytimewas significantly influenced by temperature changing at night.5) Compared with NT, LT and HT reduced the activitiesof night-time amylopectin synthesis-related enzymes and inhibited the expression of night-time related genes, which retarded formation of amylopectin, but the enzyme activitiesrelated to amylopectin synthesis was not significantly influenced by night temperature changing. 【Conclusion】High night temperature hada lesseffect on starch accumulation than low night temperature. High or low night temperatureinhibitedsucrose transport and metabolism,resulting in declined starch accumulation. The retarding of amylopectin formation was the main reason for the increase of relative content of amylose at high or low night temperature.Night temperature changes directly affected the metabolic process of starch formation at night, but the daytime activities of amylose-related enzymes wereaffected by night temperature changes, while the daytime activities of amylopectin-related enzymes werenot significantly affected by night temperature changes.

Key words: rice, night temperature change, starch accumulation, physiological process, diurnal difference.

摘要： 目的探究夜温变化对水稻淀粉形成的影响及其生理机制【方法】以优质软米浙禾香2号为材料,在灌浆初期设置31℃/20℃ (LT)、31℃/24℃ (NT)、31℃/28℃ (HT)3个夜间温度模式,测定其直链淀粉和支链淀粉含量及合成关键酶活性及相关基因的表达。结果 1)与NT相比,LT和HT处理显著降低粒重和淀粉积累,降低糊化温度和胶稠度,并影响支链淀粉链长,降低支链淀粉含量,提高直链淀粉含量,HT的影响要大于LT;2) LT和HT处理对白天叶片净光合速率的影响不显著,但显著降低籽粒中非结构性碳水化合物积累,抑制蔗糖转运基因OsSUT1、OsSUT2和OsSUT4在夜间和白天表达;3) LT 和HT处理降低夜间和白天蔗糖水解相关酶活性,增加淀粉水解酶活性,导致可溶性糖含量升高,籽粒中糖利用受阻;4)与NT相比,LT和HT处理下腺苷二磷酸葡萄糖含量呈现白天降低而夜晚升高的趋势,腺苷二磷酸葡萄糖积累及利用受到抑制,颗粒结合淀粉合酶活性随处理时间延长而显著降低,且白天酶活性也受夜间温度的影响;5)与NT相比,LT和HT处理降低了夜间支链淀粉合成相关酶活性,抑制了夜间相关基因的表达,导致支链淀粉合成受阻,但对白天酶活及相关基因表达的影响不大。结论夜间高温对淀粉积累的影响要大于夜温降低,夜间高温/低温抑制全天蔗糖转运及代谢,进而抑制淀粉积累;支链淀粉合成受阻是导致直链淀粉相对含量升高的主要原因,直链淀粉合成相关酶活性(白天)受夜温变化影响,而支链淀粉合成相关酶活性(白天)受夜温变化的影响不显著。

关键词: 水稻, 夜温变化, 淀粉积累, 生理特性, 昼夜差异

CLC Number:

Yuping ZHANG, Junke WANG, Yaliang WANG, Yanhua CHEN, Dengfeng ZHU, Huizhe CHEN, Jing XIANG, Yikai ZHANG, Xiaojun LIU, Yan ZHU, Weixing CAO. Response ofRice Starch Synthesis to Night Temperature Changes[J]. Chinese Journal OF Rice Science, 2020, 34(6): 525-538.

张玉屏, 王军可, 王亚梁, 陈燕华, 朱德峰, 陈惠哲, 向镜, 张义凯, 刘小军, 朱艳, 曹卫星. 水稻淀粉合成对夜温变化的响应[J]. 中国水稻科学, 2020, 34(6): 525-538.

Figures/Tables 12

Table 1 Temperature setting of different treatments in climate chambers.℃

温度时段 Period	夜间低温 LN	夜间适温 NT	夜间高温 HT
0:00–6:30	20	24	28
6:30–9:30	28	28	28
9:30–17:30	31	31	31
17:30–22:30	28	28	28
22:30–24:00	20	24	28
平均Average	26.3	27.7	29

Table 2 Primers used for quantitative real-time PCR.

基因 Gene	正向引物 Forward primer (5'→3')	反向引物 Reverse primer (5'→3')
OsUBQ	GCACCCTCGCCGACTACAACATCCA	CCACCTTGTAGAACTGGAGCACGGC
OsSUT1	ATGTGGCTCTGTGGTCCTATTGC	TCAACACACATCCTGTAAGAATA
OsSUT2 OsSUT4	GCTGTGCCAACCTCAAGTCTGCC TCAAAGTATGGAAGAAGGAGACCGT	GTGAGGGCAGTAACAATCAAAAC GACCTTGAACTGTATTGTTTGCGAG
OsSSⅠ	CGTGTGATGGTTGTAATGCCGAG	CTGATTATCGCCAAAAGCACCAA
OsSSⅡa	GGTGTCTATGCGTTGTTGGAATG	CTCTTTGCTCTTGCGGATAACAG
OsSSⅢa	CCCACCGCCTTCCTTCCTGCTACT	GTGAAGGGCTGGCGGGGAGACGAG
OsBEⅡb	GGTGTTTGGGAGATTTTTCTGCCTA	GGTCTTTTAGGTTGAGGATGCTTGA

Fig. 1. Comparison of 1000-grain weight, starch contents, amylopectin contents of different chain lengths, pasting temperature, and gel consistency of rice grain at different night temperatures. LT, Low night temperature treatment; NT, Normal night temperature treatment; HT, High night temperature treatment; DAT, Days after treatment. Values are Mean ± SD. Bars superscripted by different lowercase letters are significantly different at 0.05 level among treatments. The same as below.

Fig. 2. Comparison of carbohydrate accumulation in grain under different night temperature treatments. A, Contents of soluble sugar at 12:00 AM; B, Contents of soluble sugar at 24:00 PM; C, Contents of starch at 12:00 AM; D, Contents of starch at 24:00 PM; E, Non-structural carbohydrate contents at 12:00 AM; F, Non-structural carbohydrate contents at 24:00 PM.

Fig. 3. Comparison of sucrose transporter gene expression under different night temperature treatments. A, Relative expression level of OsSUT1 at 12:00 AM; B, Relative expression level of OsSUT1 at 24:00 PM; C, Relative expression level of OsSUT2 at 12:00 AM; D, Relative expression level of OsSUT2 at 24:00 PM; E, Relative expression level of OsSUT4 at 12:00 AM; F, Relative expression level of OsSUT4 at 24:00 PM.

Fig. 4. Comparison of sucrose hydrolysis-related enzymes under different night temperature treatments. A, Sucrose synthase activity at 12:00 AM; B, Sucrose synthase activity at 24:00 PM; C, Activity of soluble sucroseinvertase at 12:00 AM; D, Activity ofsoluble sucroseinvertase at 24:00 PM.

Table 3 Comparison of leaf net photosynthetic rate under different night temperature treatments.μmol/(m2·s)

处理温度Treatment	5 DAT	10 DAT	15 DAT
LT	21.8±0.5 a	22.8±0.5 a	21.8±0.5 a
NT	22.4±0.3 a	21.4±0.3 a	21.4±0.3 a
HT	22.7±0.5 a	21.7±0.5 a	19.7±0.5 b

Fig. 5. Comparison of amylose and amylopectin contents under different night temperature treatments. A, Amylose starch; B, Amylopectin.

Fig. 6. Comparison of amylose synthase activity under different night temperature treatments. A, Content of glucose adenosine diphosphate at 12:00 AM; B, Content of glucose adenosine diphosphate at 24:00 PM; C, Activity of ADP-glucose pyrophosphorylase at 12:00 AM; D, Activity of ADP-glucose pyrophosphorylase at 24:00 PM; E, Activity of particle-binding starch synthase at 12:00 AM; F, Activity of granuce-bound starch synthase at 24:00 PM.

Fig. 7. Comparison of amylopectin formation-related enzyme activities under different night temperature treatments. A, Activity of soluble starch synthase (SSS) at 12:00 AM; B, Activity of soluble starch synthase (SSS) at 24:00 PM; C, Activity of amylase branching enzyme (SBE) at 12:00 AM; D, Activity of amylase branching enzyme (SBE) at 24:00 PM; E, Activity of amylase branching enzyme (DBE) at 12:00 AM; F, Activity of amylase branching enzyme (DBE) at 24:00 PM.

Fig. 8. Comparison of starch hydrolase-related enzyme activities under different night temperature treatments. A, Activity of ɑ-amylase activity at 12:00 AM; B, Activity of ɑ-amylase activity at 24:00 PM; C, β-amylase activity at 12:00 AM; D, β-amylase activity at 24:00 PM.

Fig. 9. Comparison of sucrose transporter gene expression under different night temperatures. A, Relative expression level of OsSSⅠat 12:00 AM; B, Relative expression level of OsSSⅠat 24:00 PM; C, Relative expression level of OsSSⅡa at 12:00 AM; D, Relative expression level of OsSSⅡa at 24:00 PM; E, Relative expression level of OsSSⅢa at 12:00 AM; F, Relative expression level of OsSSⅢa at 24:00 PM; G, Relative expression level of OsBEⅡb at 12:00 AM; H, Relative expression level of OsBEⅡb at 24:00 PM.

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