Root Response Mechanism of Exogenous EBR Regulating Drought Resistance in Soybean Seedlings

doi:10.11924/j.issn.1000-6850.casb2025-0512

Abstract

Abstract:

To explore the effects of exogenous 2,4-Epibrassinolide (EBR) on root morphology and physiology of soybean seedlings under the drought stress, using ' Liaoxian No.1' as the material, the effects of 0.5-2.0 mg/L EBR treatment on root morphology, protective enzyme activity, reactive oxygen species accumulation, bleeding intensity and endogenous hormones (ABA, CTK ) of soybean seedlings under drought stress were studied by using pot water control method. The results showed that compared with CK, the drought stress treatment extremely significantly reduced the main root length, root surface area, root volume, main root diameter and root dry weight of soybean seedlings (P<0.01). Foliar spraying of 1.0-1.5 mg/L EBR could significantly alleviate the inhibition of root growth of soybean seedlings by drought stress. Among them, the main root length, root surface area, root volume, main root diameter and root dry weight of soybean seedlings treated with 1.0 mg/L EBR increased by 46.6%, 30.6%, 34.9%, 43.8% and 40.0% respectively. And all the above indicators were significantly higher than those of simple drought stress treatment. Foliar spraying 0.5-1.5 mg/L EBR significantly increased the activities of protective enzymes such as superoxidedismutase (SOD), peroxidase (POD), and catalase (CAT) in the root tips of soybean seedlings under drought stress (P<0.01), and significantly reduced the superoxide anion radical (O₂^-·) production rate and hydrogen peroxide (H₂O₂) content in the root tips of soybean seedlings under drought stress (P<0.01), reduced the ABA content in the root wound fluid to varying degrees, and increased the CTK content and root bleeding intensity. Soybean seedlings treated with 1.0 mg/L EBR had the highest protective enzyme activity in the root tip, bleeding intensity and CTK content, while the O₂^-· production rate, H₂O₂ content and ABA content were the lowest. Compared with the simple drought treatment, the SOD activity, POD activity and CAT activity in the root tips of soybean seedlings treated with 1.0 mg/L EBR increased by 14.0%, 17.2% and 50.6% respectively, the O₂^-· roduction rate and H₂O₂ content decreased by 33.0% and 17.8% respectively. Therefore, exogenous EBR alleviated the soybean drought stress by enhancing the root bleeding intensity and root tip protection enzyme activities of soybean seedlings under drought stress, increasing the CTK content, reducing the ABA content and inhibiting the active oxygen accumulation. Treatment with 1.0 mg/L EBR had the best effects on inducing drought resistance in soybean seedlings.

Key words: soybean (Glycine max L.), root growth, protective enzyme activity, reactive oxygen species accumulation, bleeding intensity, hormone content

CLC Number:

S311作物生理学

XU Fenfen, HAN Jinduo. Root Response Mechanism of Exogenous EBR Regulating Drought Resistance in Soybean Seedlings[J]. Chinese Agricultural Science Bulletin, 2026, 42(8): 53-59.

Figures/Tables 4

References 33

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处理	主根长/cm	根表面积/(cm²/株)	根体积/(cm³/株)	主根直径/mm	根干重/(g/株)
CK	13.6±1.2 aA	165.30±15.22 aA	1.20±0.20 aA	0.53±0.04 aA	0.68±0.06 aA
干旱	8.8±0.7 dC	119.86±10.17 cB	0.83±0.05 bB	0.32±0.02 cdCD	0.45±0.05 eC
干旱+0.5 mg/L EBR	10.8±0.8 bcBC	130.64±12.29 bcB	0.96±0.08 bAB	0.42±0.03 bcBC	0.56±0.04 cB
干旱+1.0 mg/L EBR	12.9±1.0 aAB	156.54±17.57 aA	1.12±0.09 aAB	0.46±0.03 bAB	0.63±0.03 abAB
干旱+1.5 mg/L EBR	11.0±0.9 bBC	136.75±10.28 bB	0.93±0.72 bB	0.38±0.03 cdBCD	0.58±0.04 bcB
干旱+2.0 mg/L EBR	9.0±0.7 cdC	125.37±11.56 bcB	0.89±0.62 bB	0.33±0.02 cdCD	0.48±0.05 deC

处理	主根长/cm	根表面积/(cm²/株)	根体积/(cm³/株)	主根直径/mm	根干重/(g/株)
CK	13.6±1.2 aA	165.30±15.22 aA	1.20±0.20 aA	0.53±0.04 aA	0.68±0.06 aA
干旱	8.8±0.7 dC	119.86±10.17 cB	0.83±0.05 bB	0.32±0.02 cdCD	0.45±0.05 eC
干旱+0.5 mg/L EBR	10.8±0.8 bcBC	130.64±12.29 bcB	0.96±0.08 bAB	0.42±0.03 bcBC	0.56±0.04 cB
干旱+1.0 mg/L EBR	12.9±1.0 aAB	156.54±17.57 aA	1.12±0.09 aAB	0.46±0.03 bAB	0.63±0.03 abAB
干旱+1.5 mg/L EBR	11.0±0.9 bBC	136.75±10.28 bB	0.93±0.72 bB	0.38±0.03 cdBCD	0.58±0.04 bcB
干旱+2.0 mg/L EBR	9.0±0.7 cdC	125.37±11.56 bcB	0.89±0.62 bB	0.33±0.02 cdCD	0.48±0.05 deC

处理	SOD活性/(U/gFW)	POD活性/(U/gFW)	CAT活性/(U/gFW)	O₂^-·产生速率/[mmol/(min·mg)]	H₂O₂含量/(μmol/gFW)
CK	132.4±12.2 cC	253.5±20.8 cC	35.7±2.2 cC	12.6±1.2 dD	23.8±1.8 dB
干旱	156.3±13.4 bB	266.4±24.6 cBC	43.3±3.6 cBC	20.3±1.8 aA	32.1±2.1 aA
干旱+0.5 mg/L EBR	168.7±15.6 abA	285.3±22.7 bB	55.4±5.2 bA	17.6±1.6 bcBC	29.2±1.7 bA
干旱+1.0 mg/L EBR	178.3±15.2 aA	312.3±13.3 aA	65.2±4.4 aA	13.6±0.8 dD	26.4±1.5 cdB
干旱+1.5 mg/L EBR	157.8±15.1 abA	283.6±15.6 bB	52.3±4.2 bB	16.3±1.5 cC	28.4±2.6 bcAB
干旱+2.0 mg/L EBR	157.0±13.5 bA	275.6±20.2 bcB	56.7±3.7 bA	18.9±1.3 abAB	30.2±2.5 abA

处理	SOD活性/(U/gFW)	POD活性/(U/gFW)	CAT活性/(U/gFW)	O₂^-·产生速率/[mmol/(min·mg)]	H₂O₂含量/(μmol/gFW)
CK	132.4±12.2 cC	253.5±20.8 cC	35.7±2.2 cC	12.6±1.2 dD	23.8±1.8 dB
干旱	156.3±13.4 bB	266.4±24.6 cBC	43.3±3.6 cBC	20.3±1.8 aA	32.1±2.1 aA
干旱+0.5 mg/L EBR	168.7±15.6 abA	285.3±22.7 bB	55.4±5.2 bA	17.6±1.6 bcBC	29.2±1.7 bA
干旱+1.0 mg/L EBR	178.3±15.2 aA	312.3±13.3 aA	65.2±4.4 aA	13.6±0.8 dD	26.4±1.5 cdB
干旱+1.5 mg/L EBR	157.8±15.1 abA	283.6±15.6 bB	52.3±4.2 bB	16.3±1.5 cC	28.4±2.6 bcAB
干旱+2.0 mg/L EBR	157.0±13.5 bA	275.6±20.2 bcB	56.7±3.7 bA	18.9±1.3 abAB	30.2±2.5 abA

激素种类	测定时间/ h	CK	干旱	干旱+0.5 mg/L EBR	干旱+1.0 mg/L EBR	干旱+1.5 mg/L EBR	干旱+2.0 mg/L EBR
ABA含量/(ng/g)	24	1.32±0.12 dC	1.53±0.15 aA	1.47±0.11 abAB	1.38±0.10 cdBC	1.42±0.12 bcBC	1.46±0.13 abAB
	48	1.35±0.09 eC	2.64±0.21 aA	2.55±0.22 bABC	2.32±0.18 dC	2.34±0.13 dC	2.43±0.19 cBC
	72	1.41±0.08 dD	1.87±0.15 aA	1.75±0.13 bABC	1.65±0.14 cC	1.69±0.15 bBC	1.76±0.16 abAB
CTK含量/(ng/g)	24	0.53±0.03 dD	0.65±0.05 cCD	0.88±0.08 aAB	0.95±0.07 aA	0.85±0.06 abAB	0.76±0.05 bBC
	48	0.55±0.02 dD	0.86±0.06 cC	1.21±0.10 bB	1.43±0.13 aA	1.25±0.11 bB	1.22±0.08 bB
	72	0.61±0.05 dD	0.93±0.06 cC	1.32 ±0.11 bB	1.53±0.15 aA	1.46±0.10 bAB	1.33±0.13 bB