外源油菜素内酯缓解水稻穗分化期高温伤害的机理研究

doi:10.16819/j.1001-7216.2019.9036

摘要/Abstract

摘要：

【目的】 明确水稻穗分化期高温下喷施2,4-表油菜素内酯(2,4-epibrassinolide, EBR)对穗生长及颖花形成的影响,并探究其生理机制。【方法】 以热敏感型水稻IR36为材料,在幼穗分化期设置40℃高温和32℃适温两个处理,并喷施EBR,研究幼穗碳水化合物供应、蔗糖代谢、细胞分裂素代谢及抗氧化能力的变化。【结果】 1)高温和适温喷施EBR,水稻每穗粒数分别比不喷施的对照增加13.7% 和45.7%,其中以喷施0.15 mg/L效果最好,缓解了高温对水稻幼穗生长的抑制,增加颖花分化数和降低颖花退化率。2)喷施EBR对叶片净光合速率无显著影响,但促进幼穗中干物质和非结构性碳水化合物积累。EBR喷施增加高温下幼穗中蔗糖转运基因OsSUT1、OsSUT2和OsSUT4的表达,并显著提高蔗糖代谢相关酶活性,EBR对高温下碳水化合物利用的促进作用大于适温处理。3)喷施EBR降低高温下细胞分裂素氧化酶基因OsCKX5和OsCKX9的表达量,同时促进细胞分裂素合成和信号调节相关基因的表达,并在适温下也表现出类似的效应。4)喷施EBR降低高温下超氧阴离子含量,增强了超氧化物歧化酶、过氧化氢酶和过氧化物酶活性。【结论】 高温下,喷施适宜浓度的EBR促进碳水化合物向幼穗的转运,抑制细胞分裂素分解,同时降低高温引起的过氧化伤害,进而缓解了高温对颖花形成的伤害。适温条件喷施EBR也对颖花形成具有一定的促进作用。

关键词: 水稻, 高温, 颖花形成, 2,4-表油菜素内酯, 生理机制

Abstract:

【Objective】The purpose of the study is to ascertain the effects of 2,4-epibrassinolide(EBR) application on rice panicle development and spikelet formation under high temperature, and to explore the physiological mechanism. 【Method】Heat-sensitive inbred rice cultivar IR36 was subjected to high temperature (HT, 40℃) and normal temperature (NT, 32℃) in climate chambers with EBR application, and the carbohydrate supplement, sucrose metabolism, cytokinin metabolism, and antioxidant capacity of young panicle were investigated. 【Result】1) EBR application increased the number of spikelets per panicle by 13.7% and 45.7% on average under HT and NT, respectively, in comparison to the control. And 0.15 mg/L EBR application level performed the highest efficiency in increasing the number of spikelet number, EBR application prompted panicle development and spikelet differentiation, and inhibited spikelet degeneration. 2) EBR application did not influence leaf net photosynthesis, meanwhile increased the dry matter and nonstructural carbohydrate accumulation in young panicles. Under high temperature, EBR application significantly upregulated the expression levels of sucrose transport genes OsSUT1, OsSUT2, and OsSUT4, and EBR enhanced the related enzymes activities of sucrose metabolism especially in HT than in NT. 3) EBR application reduced the expression levels of cytokinin oxidase genes, OsCKX5 and OsCKX9, under HT. Meanwhile, EBR application promoted the genes expression involved in cytokinin biosynthesis and signal transduction both under HT and NT treatments. 4) EBR application increased the activities of superoxide dismutase, catalase and peroxidase, reduced the content of superoxide under HT. 【Conclusion】Under HT conditions, EBR application at appropriate concentration could alleviate heat damage to spikelet formation by promoting carbohydrates transportation to young panicles, inhibiting cytokinin oxidation, and reducing peroxidation injures. Meanwhile, EBR application could promote spikelet formation under normal temperature.

Key words: rice (Oryza sativa L.), high temperature, spikelet formation, 2,4-epibrassinolide, physiological mechanism

中图分类号:

陈燕华, 王亚梁, 朱德峰, 石庆华, 陈惠哲, 向镜, 张义凯, 张玉屏. 外源油菜素内酯缓解水稻穗分化期高温伤害的机理研究[J]. 中国水稻科学, 2019, 33(5): 457-466.

Yanhua CHEN, Yaliang WANG, Defeng ZHU, Qinghua SHI, Huizhe CHEN, Jing XIANG, Yikai ZHANG, Yuping ZHANG. Mechanism of Exogenous Brassinolide in Alleviating High Temperature Injury at Panicle Initiation Stage in Rice[J]. Chinese Journal OF Rice Science, 2019, 33(5): 457-466.

图/表 8

表1 实时荧光定量PCR引物序列

Table 1 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	AACCAGCTGAGGCCCAAGA	ACGATTGATTTAACCAGTCCATGA
OsSUT1	CCACCTCGGTAGAAGAGAATAA	CCATTCATTACACACTAATTACCAA
OsSUT2	AGGAGGAGAGGTCACCGATAA	CCAACATCCAATGTACAACAGCA
OsSUT4	TTTGGCTGAGCAGAACACCA	ATGTCATTCGGGCAGAGCTT
OsLOGL2	GAGCGCACAGAAAAGAGAAGC	GGCATGAGTGCTTTTGGAAT
OsLOGL3	GTGCTGCATTGTCTGCAGTT	GGTCATGAGAGTCTTGGGGA
OsCKX5	CGCTGCTGGGCGAGCTGAAT	CGCCTTGTGCACGCGGTCTA
OsCKX9	GCCAGGATTCCTCTTGAACCTGC	ACGCACTGGGTCCTGCGGAT
OsRR2	ACGATCTTCTCAAAGCCATCAAG	TGAGAGGCTTAAGGATGAAATCCT
OsRR5	ACCGAATGTGAGCATGATTATCA	CCTTGACCTTCTTCAGGAGTTCATA
ORR2	TGGGTAGTTCAAAGCTGCAG	GACTAGAAAAGGCGCTGACA
ORR4	TCAGTGGTGGTCTAGATGAC	CGATGATTAACGAGAATTTTAC

表2 高温下不同浓度EBR喷施对水稻单株产量及其构成的影响

Table 2 Rice yield and its components per plant under exposure to different concentrations of exogenous 2, 4-epibrassinolide (EBR) at high temperature.

处理 Treatment	EBR浓度 Concentration of EBR/(mg·L^-1)	单株穗数 Panicle number per plant	每穗粒数 Number of spikelets per panicle	结实率 Seed setting rate/%	千粒重 1000-grain weight/g	单株产量 Yield per plant /g
NT	0.00	12.0±1.0 a	100.7±11.2 a	81.4±1.8 ab	19.6±0.3 a	19.1±0.1 b
	0.05	11.3±0.6 a	105.5±4.4 b	82.1±1.6 ab	19.2±1.1 a	18.8±1.3 b
	0.10	12.3±0.6 a	111.2±3.4 abc	86.9±0.2 a	19.4±1.1 a	23.1±1.8 a
	0.15	12.7±0.6 a	121.0±5.2 a	75.8±5.8 b	18.6±0.8 a	21.7±4.9 ab
	0.30	12.3±1.5 a	113.9±5.2 ab	79.8±2.8 b	19.1±0.8 a	21.3±4.7 ab
	0.50	13.3±1.5 a	105.8±6.5 bc	80.0±2.9 b	19.1±0.7 a	21.6±2.4 ab
HT	0.00	12.3±0.6 a	52.5±0.9 d	46.6±7.3 b	18.0±1.0 a	5.4±0.5 c
	0.05	13.0±2.0 a	71.0±4.8 bc	49.8±4.9 b	17.6±0.3 a	8.1±1.0 b
	0.10	12.0±1.0 a	83.2±3.1 a	45.9±6.8 b	17.7±0.2 a	8.1±1.2 b
	0.15	11.7±0.6 a	85.9±4.2 a	65.6±9.5 a	17.7±0.3 a	11.6±1.3 a
	0.30	11.3±0.6 a	76.5±1.6 b	49.4±1.4 b	18.1±0.5 a	9.2±0.4 b
	0.50	12.7±0.6 a	65.7±4.7 c	55.9±6.9 ab	18.0±0.7 a	8.4±1.6 b

图1 高温下喷施EBR(0.15 mg/L)对幼穗发育及颖花形成的影响 A–高温及适温处理7 d和15 d的幼穗表型,标尺分别为0.5 cm和1 cm; B–高温和适温处理15 d水稻抽穗期穗部表型, 标尺为2.5 cm; C–0.15 mg/L EBR喷施对高温及适温下水稻颖花分化数的影响;D–0.15 mg/L EBR喷施对高温及适温下水稻颖花退化率的影响。数据为平均数±标准差。不同小写字母表示处理间差异显著(P<0.05)。下同。

Fig. 1. Effect of exogenous 2, 4-epibrassinolide (EBR) application(0.15 mg/L) on young panicle development and spikelet formation under high temperature. A, Young panicle under high temperature and normal temperature for 7 days (bar=0.5 cm) and 15 days(bar=1 cm); B, Panicle morphologies at heading stage at high temperature and normal temperature for 15 days(bar=2.5 cm); C, Effect of 0.15 mg/L exogenous EBR on the number of differentiated spikelets; D, Effect of 0.15 mg/L exogenous EBR application on the proportion of degenerated spikelets. Values are Mean±SD; Bars superscripted by different lowercase letters are significantly different at 0.05 level among treatments. The same as below.

图2 高温下喷施EBR (0.15 mg/L)对幼穗中碳水化合物分配及转运的影响 A–顶部全展叶净光合速率; B–幼穗干物质积累; C–非结构性碳水化合物含量; D–OsSUT1相对表达量; E–OsSUT2相对表达量; F–OsSUT4相对表达量。

Fig. 2. Effect of 0.15 mg/L exogenous 2, 4-epibrassinolide (EBR) application on carbohydrate distribution and transportation of young panicles under high temperature. A, Leaf net photosynthesis; B, Dry matter accumulation of young panicles; C, Non-structural carbohydrate content; D, Relative expression of OsSUT1 of young panicles; E, Relative expression of OsSUT2 of young panicles; F, Relative expression of OsSUT4 of young panicles.

图3 高温下喷施EBR (0.15 mg/L) 喷施对幼穗中蔗糖利用相关酶活性的影响

Fig. 3. Effect of 0.15 mg/L exogenous 2, 4-epibrassinalide (EBR) application on enzymes activities related to sucrose utilization under high temperature.

图4 高温下喷施EBR对幼穗玉米素核苷含量的影响

Fig. 4. Effect of 2, 4-epibrassinolide (EBR) application on zeatin riboside content in young panicles under high temperature.

图5 高温下喷施EBR (0.15 mg/L)对幼穗中细胞分裂素相关代谢基因表达的影响

Fig. 5. Effect of 0.15 mg/L EBR application on relative expression of cytokinin metabolism genes under high temperature.

图6 高温下喷施EBR (0.15 mg/L) 对幼穗抗氧化能力的影响

Fig. 6. Effect of 0.15 mg/L exogenous 2, 4-epibrassinolide (EBR) application on antioxidant capacity of young panicles.

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