褪黑素对玉米幼苗根系发育和抗旱性的影响

doi:10.13560/j.cnki.biotech.bull.1985.2020-0575

摘要/Abstract

摘要：

褪黑素是一种在生物体内广泛存在的吲哚胺类化合物,参与植物的多种生理和生化过程。近年来研究认为褪黑素可以不同程度地增强植物的抗逆性,但对其作用机理仍知之甚少。通过两种褪黑素的施用方法,详细研究了褪黑素对于玉米根系发育和抗旱性的影响。首先,采用水培根灌褪黑素的方法对玉米幼苗的根系和生长状况进行分析,结果表明施加褪黑素显著提高多种玉米幼苗根系参数,包括根长、根表面积、根体积和侧根数目等。其次,采用盆栽浸种褪黑素的方法,对叶片相对含水量、光合作用、抗氧化酶活性、地上部分生物量等进行测定,结果表明在干旱胁迫条件下,褪黑素浸泡种子的处理方式能够提高植株的光合速率、气孔导度和蒸腾速率,增强抗氧化酶活性以及降低活性氧和丙二醛含量,证明褪黑素促进植物根系发育,减轻氧化损伤,缓解光合抑制,改善植物水分状况,从而提高植物抗旱性。

关键词: 褪黑素, 根系构型, 抗氧化, 光合作用, 抗旱性

Abstract:

Melatonin（N-acetyl-5-methoxy-tryptamine）,an indoleamine neurohormone widely existing in organism,involves in many physiological and biochemical processes of plants. Recent studies understand that melatonin application may improve plant stress tolerance at varied level;however,the specific underlying mechanisms are still not fully understood. The current study was carried out to investigate the effect of melatonin on maize root system and drought tolerance via 2 applications of melatonin. Firs,the method of hydroponic root maize and irrigating melatonin were used to analyze the root system and growth status of maize seedlings. The results showed that the application of melatonin significantly improved a variety of maize seedling root parameters,including root length,root surface area,root volume,number of lateral roots,etc. Secondly,the method of melatonin-soaked seeds in pot was used to determine the relative water content of leaves,photosynthesis,antioxidant enzyme activity,and above-ground biomass. The results showed that under drought stress,the method of melatonin-soaked seed improved plant photosynthesis rate,stomatal conductance and transpiration rate,enhanced antioxidant enzyme activity,and reduced reactive oxygen species and malondialdehyde content. Our current findings hereby confirmed the beneficial effects of melatonin application in enhancing maize drought tolerance by promoting root growth,reducing oxidative damages,eliminating photosynthetic inhibition,and improving plant water status.

Key words: melatonin, root system, antioxidant, photosynthesis, drought tolerance

马旭辉, 陈茹梅, 柳小庆, 赵军, 张霞. 褪黑素对玉米幼苗根系发育和抗旱性的影响[J]. 生物技术通报, 2021, 37(2): 1-14.

MA Xu-hui, CHEN Ru-mei, LIU Xiao-qing, ZHAO Jun, ZHANG Xia. Effects of Melatonin on Root Growth and Drought Tolerance of Maize Seedlings[J]. Biotechnology Bulletin, 2021, 37(2): 1-14.

图/表 9

图1 水培根灌和浸种盆栽两种外源褪黑素施加方式对植物生长发育的影响 A：水培法植株的地上部分表型;B：盆栽法植株的地上部分表型;C：水培法植株在正常条件和干旱条件下根系和地上部分的生物量;D：盆栽法植株在正常条件和干旱条件下地上部分的生物量。*表示显著的统计差异,****P<0.0001,***P<0.001,**P<0.01,*P<0.05

表1 玉米根系构型构相关特征概述

分类	特征	缩写	单位	描述
主根	主根长度	PAL	cm	主根（包括主根上的侧根）长度
	主根表面积	PSA	cm²	主根（包括主根上的侧根）表面积
	主根体积	PRV	cm³	主根（包括主根上的侧根）体积
	主根长度	PRL	cm	主根（不包括主根上的侧根）长度
	侧根数目	LRN_PR	branch	主根上侧根的数目
种子根	种子根的长度	SAL	cm	种子根（包括种子根上的侧根）的长度
	种子根的表面积	SSA	cm²	种子根（包括种子根上的侧根）的表面积
	种子根的体积	SRV	cm³	种子根（包括种子根上的侧根）的体积
总根	总根长	TRL	cm	整个根系的长度
	总根表面积	TSA	cm²	整个根系的表面积
	总根体积	TRV	cm³	整个根系的体积

图2 具有代表性的正常条件下和PEG6000诱导的干旱条件下的根的扫描图像

表2 正常条件下水培根灌褪黑素对根系构型相关性状影响的统计总结

分类	特征	0 μmol/L		1 μmol/L		Significance
分类	特征	Mean	SD	Mean	SD	Significance
总根	TRL	150.375	32.656	178.512	35.414	**
	TSA	27.414	4.482	37.812	11.272	**
	TRV	0.564	0.096	0.593	0.100	***
主根	PAL	64.432	11.777	88.796	16.124	**
	PRL	23.265	0.959	28.709	0.962	****
	PSA	8.557	1.333	9.053	1.353	***
	PRV	0.348	0.487	0.370	0.463	****
	LRNPR	207	21.818	239	16.244	****
种子根	SAL	85.942	20.635	89.716	25.746	**
	SSA	18.857	3.694	28.759	2.878	***
	SRV	0.216	0.255	0.223	0.192	*

表3 PEG6000 诱导的干旱胁迫条件下水培添加褪黑素对根系构型相关性状影响的统计总结

分类	特征	0 μmol/L		1 μmol/L		Significance
分类	特征	Mean	SD	Mean	SD	Significance
总根	TRL	105.7	20.737	132.2	9.196	****
	TSA	15.81	4.531	25.82	3.389	***
	TRV	0.332	0.058	0.469	0.06	***
主根	PAL	53.954	7.444	61.309	11.265	****
	PRL	18.267	1.989	21.062	2.677	****
	PSA	7.155	1.142	8.162	0.933	*
	PRV	0.159	0.013	0.312	0.014	**
	LRNPR	119	18.788	132	24.615	**
种子根	SAL	51.746	21.368	70.891	15.744	***
	SSA	8.655	4.477	17.658	5.169	***
	SRV	0.123	0.266	0.158	0.187	**

图3 水培根灌和浸种盆栽两种褪黑素处理方式对ROS和MDA含量的影响 A,B：组织化学染色测定超氧阴离子O2-;C,D：过氧化氢（H2O2）的含量;E,F：丙二醛（MDA）的含量。A、C、E测定的是水培法的植株,B、D、F测定的是盆栽法的植株。*P≤ 0.05;**P ≤ 0.01;*** P≤ 0.001;**** P≤ 0.0001

图4 水培根灌和浸种盆栽两种褪黑素处理方式对植株叶片相对含水量的影响 A：水培法植株叶片的相对含水量;B：盆栽法植株叶片的相对含水量。*P≤ 0.05;**P ≤ 0.01;*** P≤ 0.001;**** P≤ 0.0001。

图5 水培根灌和浸种盆栽两种褪黑素处理方式对玉米植株抗氧化酶活性的影响 A,B：过氧化氢酶（CAT）活性;C,D：超氧化物歧化酶（SOD）活性;E,F：过氧化物酶（POD）活性;A、C、E测定的是水培法的植株,B、D、F测定的是是盆栽法的植株。*P≤ 0.05;**P ≤ 0.01;*** P≤ 0.001;**** P≤ 0.0001

图6 褪黑素浸种对气体交换参数,叶绿素含量,叶绿素荧光以及相对含水量的影响 A：气孔导度;B：光合速率;C：蒸腾速率;D：叶绿素含量;E：叶绿素荧光。*P≤ 0.05;**P ≤ 0.01;*** P≤ 0.001;**** P≤ 0.0001

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