灌浆期干旱胁迫对不同小麦品种的生理性状与根系生长的影响
Effects of Drought Stress during Grain Filling Period on Physiological and Root Characteristics of Different Wheat Cultivars
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收稿日期: 2023-02-28 修回日期: 2023-03-1 网络出版日期: 2023-09-15
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Received: 2023-02-28 Revised: 2023-03-1 Online: 2023-09-15
作者简介 About authors
薛鑫雨,主要从事小麦抗逆生理学研究,E-mail:
为明确灌浆期干旱胁迫对不同品种小麦生理特性和根系生长的影响,以高产高抗新品种郑麦1860和对照品种百农207、周麦18为材料,研究了灌浆期干旱处理对小麦根生长和生理性状的影响。结果表明,干旱胁迫下,郑麦1860的净光合速率(Pn)显著高于周麦18,郑麦1860与百农207的超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和过氧化物酶(POD)活性提高,同时郑麦1860具有更高的根冠比、根尖数以及根表面积。与百农207和周麦18相比,郑麦1860的丙二醛含量在复水后与对照组差异最小。试验结果表明灌浆期干旱胁迫下郑麦1860能维持较高的Pn,稳定籽粒产量。通过提高SOD、CAT和POD活性从而加快谷胱甘肽再生,通过促进还原型谷胱甘肽/氧化型谷胱甘肽升高来减缓膜脂过氧化损伤。并且郑麦1860具有更强的吸水能力,在干旱胁迫下清除多余活性氧的能力更强,从而减少干旱胁迫对膜结构造成的损伤。
关键词:
In order to study the effects of drought stress during grain filling period on physiological and root characteristics among different wheat cultivars, the new variety Zhengmai 1860 with high yield and high resistance, Bainong 207 and Zhoumai 18 were selected as experimental materials. The results showed the net photosynthetic rate (Pn) of Zhengmai 1860 was significantly higher than that of Zhoumai 18, the activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) in Zhengmai 1860 and Bainong 207 increased under drought stress, meanwhile, Zhengmai 1860 had higher ratio of root to shoot, the number of root tips and root surface. Compared with Bainong 207 and Zhoumai 18, the malonaldehyde (MDA) content of Zhengmai 1860 was less than that of the control group after rehydration. The results also showed that Zhengmai 1860 could maintain a high Pn and stabilize grain yield under drought stress at grain filling stage. By increasing activities of SOD, CAT and POD, it accelerated the regeneration of glutathione and promoted the increase of reduced glutathione/oxidized glutathione to slow down the membrane lipid peroxidation damage. Furthermore, Zhengmai 1860 has stronger water absorption capacity, greater ability to remove excess reactive oxygen species under drought stress, thus reducing the damage of membrane structure caused by drought stress.
Keywords:
本文引用格式
薛鑫雨, 詹文博, 陈新宜, 周瑞祥, 王永霞, 薛瑞丽, 李华, 汪月霞, 李艳.
Xue Xinyu, Zhan Wenbo, Chen Xinyi, Zhou Ruixiang, Wang Yongxia, Xue Ruili, Li Hua, Wang Yuexia, Li Yan.
小麦(Triticum aestivum L.)是世界上最重要的粮食作物之一[1]。在我国半干旱地区生长的冬小麦占全国的60%,干旱胁迫导致的小麦产量损失高达30%[1-2]。小麦幼苗期和灌浆期对干旱胁迫最为敏感,在干旱胁迫下小麦叶片会变黄萎蔫、光合能力变弱、合成物质无法转运到籽粒中,导致小麦产量急剧下降[3-4]。干旱促使小麦发生气孔关闭、叶片超微结构改变、细胞脱水、质膜过氧化、抗氧化能力和内源激素降低等一系列连锁反应,降低了其水分含量,从而限制了小麦的光合作用,进而阻碍小麦的生长。为了缓解环境胁迫对其造成的伤害,植物可以通过调节根系的生物量分配,提高水分吸取能力来提高耐旱性[5-6]。干旱胁迫下,植物的气孔导度和细胞质膜透性会发生改变[7],细胞膜透性会提高,电解质外渗[8]。根是吸收水分和养分的重要器官,在干旱胁迫下,发达的根系可以吸收更多的水分,提高植物的耐旱能力[9]。
谷胱甘肽是参与细胞防御的非酶抗氧化剂之一[11]。还原型谷胱甘肽与氧化型谷胱甘肽的比值(GSH/GSSG)会在各种逆境胁迫的作用下发生变化[17],GSH/GSSG增大可以保护叶绿体免受ROS损伤[18]。Hasanuzzaman等[19]发现,非生物胁迫下补充谷胱甘肽可以增强抗氧化酶的活性并减少ROS的产生。干旱胁迫下,植物体内的GSSG转化为GSH,并在抗坏血酸―谷胱甘肽(AsA-GSH)循环消除H2O2分子中起关键作用,所以维持适当的GSH/GSSG对于保护DNA、蛋白质和脂质在干旱胁迫条件下免受氧化至关重要[18]。前人研究多数基于单一品种小麦叶片幼苗期干旱胁迫下GSH含量的变化,而对不同品种小麦灌浆期叶片中的SOD、POD和CAT等活性以及GSH含量在干旱胁迫下的变化尚不明确。
为了探讨干旱胁迫及复水对灌浆期不同品种小麦保护酶活性及根特性的影响。本研究以小麦新品种郑麦1860为研究对象,百农207与周麦18为对照,比较耐干旱能力不同的小麦品种在干旱胁迫下灌浆期根生长、叶片光合特性、GSH含量和保护酶相关基因表达的差异,以此分析不同品种小麦灌浆期干旱胁迫下及复水缓解的生理机制,为高产高抗小麦品种的培育以及高效耐旱栽培技术提供理论参考。
1 材料与方法
1.1 供试材料
以百农207、周麦18和郑麦1860(来自河南省农业科学院作物分子育种研究院)为供试材料,郑麦1860为新品种,具有高产高抗的特性。
1.2 试验设计
选用无病虫害、大小均匀、颗粒饱满的籽粒,用5%的H2O2消毒5 min,平铺于放有蒸馏水浸湿滤纸的培养皿中。后于温度25 ℃、湿度30%的恒温培养箱中进行发芽与幼苗培养,待小麦幼苗培养3 d后,挑选长度一致的幼苗移植于河南省农业科学院现代农业科技试验示范基地,每个品种设6组重复。将供试土壤混匀后装盆并播种,每盆装土1.6 L(营养土:蛭石=3:1),盆内径0.24 m,高0.18 m,每盆种植3株,每个品种种植30盆,植物生长期间需要保持土壤最大持水量的70%以上。每次每盆施肥50 g,施肥时间和频率为小麦分蘖、拔节、孕穗期以及灌浆期时每2周1次。肥料包括尿素(含N 46%)、磷肥(含P2O5 46%,含N 18%)和钾肥(含K2O 60%)。把小麦随机分为对照组(CK)和干旱组(D)。在开花期时,将处于同一开花时间且长势相同的3个小麦品种进行挂牌定株并记录开花日期,于花后15 d的灌浆前中期对挂牌定株的小麦进行控水干旱处理并记录数据。对照组小麦的土壤持水量为100%,干旱组小麦干旱胁迫处理7 d,土壤持水量降至20%时,于上午10:00取旗叶中部包裹于锡箔纸中,统一进行复水处理,复水2 d后进行取样,并放入液氮中,于-80 ℃超低温冰箱中保存。
1.3 测定项目与方法
1.3.1 干物质及根系生长
选取处于幼苗期,不同处理长势一致的小麦,冲洗干净后将小麦植株分为地上部(茎叶)和地下部(根系)2部分,测鲜重后置于电热恒温鼓风干燥箱中105 ℃杀青15 min,然后85 ℃恒温烘干10 h至恒重,进行称重,再计算根冠比,每组5次重复。选取处理后的小麦各10株,清洗后平铺于观察板上,加入去离子水浸没根系,利用根状扫描仪(EPSON EXPRESSION 12000XL)扫描灌浆期根部图片,后采用Win-RHIZO系统(Regent Instruments Inc.,Quebec,加拿大)测量获得总根长(Len)、根表面积(SA)、根系平均直径(AvgD)、总根尖数(NTips)和分枝数(NForks),果取平均值。
1.3.2 光合参数
采用LI-6400便携式光合仪测量净光合速率(Pn),实验室幼苗光源设定在400 µmol/(m2·s)。干旱处理后,每组取叶片10片,利用无色指甲油印模,然后用透明胶带把印模沾掉,放置在一个干净透明的载玻片上进行光学观察。使用与计算机系统相连的明亮视野显微镜(LEICA DM2500,德国)分析气孔开度,每组数据5次重复。
1.3.3 MDA含量
称取1 g叶片,用预冷的研钵迅速冷冻研磨,采用硫代巴比妥酸法测定小麦叶片MDA含量[20]。每组数据3次重复。
1.3.4 细胞质膜透性
参照刘建新等[21]的方法,取小麦叶片(除去叶中脉),各取30个直径0.5 cm的叶片,浸于试管中抽真空15 min,每5 min取出摇晃一次,直至叶片内空气排出,全部沉于试管底部,28 ℃处理30 min,测定电导率(E0),然后28 ℃保温30 min,测定电导率(Ep)。最后将试管置于沸水中15 min,冷却至室温,摇匀后立即测定总电导率(Et)。每组3次重复。
1.3.5 叶片SOD、POD和CAT活性
参照Ghahremani等[20]的方法,将冷冻小麦旗叶叶片1 g在50 mmol/L PBS(pH 7.8)中冰浴研磨,加入预冷的聚乙烯吡咯烷酮(PVP,1%)和乙二胺四乙酸(EDTA,0.1 mmol/L),超速震荡混匀后,将匀浆后的试剂进行低温离心(15 min,12 000转/min,4 ℃),取上清液(酶蛋白的提取液)测定抗氧化酶活性。采用氮蓝四唑光化还原法测定SOD活性,采用过氧化氢还原法测定CAT活性,根据愈创木酚的氧化测定POD活性。每组3次重复。
1.3.6 GSH和GSSG含量
采用索莱宝的谷胱甘肽GSSG测定试剂盒(Solarbi,北京,货号BC1175)测定GSH和GSSG含量。取冷冻小麦旗叶(1 g)冰浴研磨,加入H2O2引发反应,用分光光度计在412 nm处记录30 s、150 s GSH转化为GSSG过程中吸光度的变化。每组数据3次重复。
1.3.7 qRT-PCR分析相关基因
采用OminiPlant RNA Kit(DNase I)试剂盒提取小麦总RNA,并采用超微量核酸分析仪检测总RNA的浓度和纯度。采取HiScript II Q RT SuperMix for qPCR试剂盒进行逆转录合成第一条cDNA链,在Primer 5.0设计相关引物(
表1 实时荧光定量PCR引物信息
Table 1
基因名称Gene name | 引物序列Primer sequence (5′-3′) |
---|---|
SOD-Cu/Zn | F:CGCTCAGAGCCTCCTCTTT R:CTCCTGGGGTGGAGACAAT |
FeSOD | F:GTCCTACTACGGCCTCACCA R:ACGTAGTCCTGCTGGTGCTT |
MnSOD | F:CAGAGGGTGCTGCTTTACAA R:GGTCACAAGAGGGTCCTGAT |
CAT | F:CCATGAGATCAAGGCCATCT R:ATCTTACATGCTCGGCTTGG |
POD | F:TGGGCATGGGGCTTCTGCA R:GCGAGGAATGGGGGGTTGATG |
Actin | F:GGAATCCATGAGACCACCTAC R:GACCCAGACAACTCGCAAC |
1.4 数据处理
利用Excel软件进行作图和分析,结果用平均值±标准差(mean±SD)来表示,并用单因素方差分析(ANOVA)方法比较处理间差异显著性(P<0.05)。
2 结果与分析
2.1 灌浆期干旱胁迫对不同品种小麦生长的影响
表2 灌浆期干旱胁迫对不同品种小麦根系生长的影响
Table 2
处理 Treatment | 品种 Variety | 总根长 Len (cm) | 根表面积 SA (cm2) | 根投影面积 PA (cm2) | 根系平均直径 AvgD (mm) | 总根尖数 NTipS | 分枝数 NForkS |
---|---|---|---|---|---|---|---|
对照CK | 百农207 | 1225.89±3.25d | 610.52±6.55c | 194.34±2.69b | 1.59±0.04a | 8848±14d | 12 123±25d |
郑麦1860 | 3767.47±7.34b | 673.39±2.74b | 214.35±4.13ab | 0.57±0.02c | 19 218±7a | 35 726±10a | |
周麦18 | 4498.28±7.92a | 869.46±9.64a | 276.76±6.14a | 0.62±0.02c | 18 749±11a | 39 078±9a | |
干旱组D | 百农207 | 1917.80±10.66c | 472.95±4.44d | 150.55±7.35c | 0.79±0.03c | 12 857±5bc | 15 000±23c |
郑麦1860 | 2067.51±15.45c | 691.12±5.96b | 219.99±9.52ab | 1.06±0.06b | 14 832±12b | 23 143±15b | |
周麦18 | 1576.93±8.66d | 620.53±4.87c | 197.52±6.97b | 1.25±0.05ab | 9595±40d | 14 672±19c |
不同小写字母表示处理间显著差异(P < 0.05),下同。
The different lowercase letters indicate significant difference between treatments (P < 0.05), the same below.
图1
图1
干旱胁迫下不同品种小麦根部表型
Fig.1
Root phenotypes of different wheat varieties under drought stress
从表3可以看出,CK和干旱处理下,周麦18的根干重和茎干重均显著低于郑麦1860和百农207(P<0.05)(除了CK组茎干重),CK组的郑麦1860根冠比相较于百农207和周麦18分别高出了15.6%和22.4%(P<0.05)。干旱胁迫7d时,3个品种小麦根冠比均上升,其中百农207根冠比提高了34.8%(P<0.05),最为显著。与CK相比,干旱胁迫下3个小麦品种的穗粒数均降低,百农207和周麦18分别下降12.0%和13.6%,郑麦1860仅下降了6.0%(P<0.05)。干旱胁迫导致3个小麦品种的产量均显著降低,但郑麦1860下降幅度相对较小。
表3 干旱胁迫对不同品种小麦生物量、千粒重、产量、穗粒数的影响
Table 3
处理 Treatment | 品种 Variety | 根干重(g/株) Root dry weight (g/plant) | 茎干重(g/株) Stem dry weight (g/plant) | 根冠比 Root-shoot ratio | 千粒重 1000-grain weight (g) | 穗粒数 Grain number per spike | 产量 Yield (kg/hm2) |
---|---|---|---|---|---|---|---|
对照CK | 郑麦1860 | 9.01±0.97a | 50.01±6.01a | 0.18±0.02ab | 50.45±0.93a | 50±4b | 8208.0±50.1a |
百农207 | 8.15±0.99a | 50.09±5.10a | 0.16±0.01b | 42.11±0.62c | 58±3a | 8068.5±62.3b | |
周麦18 | 6.79±0.68bc | 45.26±4.20ab | 0.15±0.01b | 47.84±0.86b | 44±3d | 7702.3±71.4c | |
干旱组D | 郑麦1860 | 8.74±0.70ab | 41.60±3.10ab | 0.21±0.02ab | 42.09±0.81c | 47±3c | 6847.9±43.6d |
百农207 | 7.85±0.71ab | 35.70±2.00c | 0.22±0.01a | 34.02±0.72e | 51±2b | 6518.4±72.3e | |
周麦18 | 5.10±0.57c | 30.50±2.80d | 0.17±0.01b | 38.28±0.95d | 38±3e | 6163.1±78.8f |
2.2 灌浆期干旱胁迫对不同品种小麦叶片气孔和Pn的影响
从表4可以看出,干旱胁迫7 d后,郑麦1860气孔孔径大小(宽度/长度)明显高于百农207和周麦18,复水2 d后,郑麦1860气孔孔径大小和气孔开度在3个品种中与CK组相差最小,CK组郑麦1860的Pn相较于百农207和周麦18分别高出了3.4%和8.3%(P<0.05)。干旱胁迫7 d时,郑麦1860和百农207的Pn相较于周麦18分别高出了18.2%和21.6%(P<0.05)。
表4 干旱胁迫对不同品种小麦气孔孔径、气孔开度和Pn的影响
Table 4
处理Treatment | 品种Variety | 气孔孔径Stomatal aperture size (μm) | 气孔开度Stomatal open size (μm) | Pn [μmol/(m2·s)] | |
---|---|---|---|---|---|
干旱胁迫7 d 7 d after drought stress | CK | 郑麦1860 | 0.63±0.04a | 0.30±0.02a | 26.30±0.54a |
百农207 | 0.54±0.01ab | 0.30±0.04a | 25.03±0.47b | ||
周麦18 | 0.55±0.04ab | 0.30±0.03a | 24.23±0.52c | ||
D | 郑麦1860 | 0.55±0.04ab | 0.15±0.01b | 23.23±0.26cd | |
百农207 | 0.53±0.00b | 0.11±0.01c | 22.57±0.52d | ||
周麦18 | 0.53±0.05b | 0.06±0.01d | 19.10±0.42e | ||
复水后2 d 2 d after rewatering | CK | 郑麦1860 | 0.62±0.03a | 0.22±0.00a | 26.30±0.54a |
百农207 | 0.51±0.01c | 0.18±0.01b | 25.43±0.47b | ||
周麦18 | 0.66±0.02a | 0.17±0.00b | 24.30±0.62b | ||
D | 郑麦1860 | 0.50±0.02c | 0.19±0.01b | 25.40±0.56ab | |
百农207 | 0.53±0.02bc | 0.13±0.00c | 24.57±0.59b | ||
周麦18 | 0.57±0.02b | 0.12±0.00c | 21.10±0.57c |
2.3 灌浆期干旱胁迫对不同品种小麦叶片MDA含量和细胞质膜透性的影响
从图2可以看出,干旱胁迫7 d后,3个小麦品种的叶片MDA含量均不同程度地升高,其中以周麦18增加最多。复水2 d后,3个品种的小麦叶片的MDA含量均发生下降,其中郑麦1860的MDA含量最低,表明干旱胁迫下郑麦1860的膜脂过氧化程度更低,损伤更小,其相较于百农207和周麦18具有较强的抗干旱能力。
图2
图2
干旱胁迫及复水对不同品种小麦旗叶MDA含量和细胞质膜透性的影响
不同小写字母表示处理间显著差异(P < 0.05),下同。
Fig.2
Effects of drought stress and rehydration on MDA contents and cytoplasmic membrane permeability in flag leaves of different wheat varieties
The different lowercase letters indicate significant difference between treatments (P < 0.05), the same below.
同时,经干旱胁迫7 d后,3个品种小麦叶片的质膜相对透性发生不同程度地升高,质膜的相对损伤程度为周麦18>百农207>郑麦1860,干旱后复水处理2 d,百农207、郑麦1860、周麦18的质膜相对透性均出现不同程度降低,但周麦18细胞质膜透性相较于郑麦1860与百农207仍较高,表明周麦18相对于郑麦1860以及百农207在干旱情况下受损严重,同时复水后缓解干旱胁迫对其造成伤害的能力也相对较差。
2.4 灌浆期干旱胁迫对不同品种小麦叶片保护酶活性的影响
从图3可以看出,干旱胁迫7 d后,3个小麦品种的叶片SOD活性均显著上升,其中郑麦1860与百农207的SOD活性上升程度更高,其活性显著高于CK组的周麦18。经复水2 d处理后,郑麦1860和百农207的抗氧化酶活性均趋于CK组,但周麦18的POD活性仍显著高于CK组,处于同期处理下最高水平,而郑麦1860与百农207能较好地缓解干旱胁迫对小麦造成的伤害。
图3
图3
干旱胁迫及复水对不同品种小麦叶片SOD、CAT、POD活性以及GSH、GSSG、GSH/GSSG的影响
Fig.3
Effects of drought stress and rehydration on SOD, CAT, POD activities and GSH, GSSG, GSH/GSSG in leaves of different wheat varieties
2.5 灌浆期干旱胁迫对不同品种小麦GSH和GSSG含量的影响
从图3可以看出,干旱胁迫7 d后,3个小麦品种的GSH含量均不同程度上升,其中百农207和郑麦1860的GSH含量上升幅度远高于周麦18。百农207和郑麦1860与周麦18相比也具有更高的GSH/GSSG,复水2 d后与CK组无显著差异。表明百农207和郑麦1860在干旱胁迫下具有更好的调节作用,耐旱能力更强,在复水后能更好地缓解干旱胁迫对自身造成的伤害。
2.6 干旱胁迫对灌浆期不同品种小麦保护酶相关基因表达水平的影响
从图4可以看出,干旱胁迫7 d后,百农207和郑麦1860在干旱胁迫下的SOD-CuZn、MnSOD和FeSOD相关基因表达水平的上升程度均明显高于周麦18,3种小麦的CAT相关基因表达水平均显著提高,其中郑麦1860上升幅度最大。复水2 d后,3个品种中郑麦1860的抗氧化酶相关基因表达水平与CK组差异最小,进一步表明郑麦1860在复水后能更好地缓解干旱胁迫对自身造成的伤害。
图4
图4
干旱胁迫及复水对不同品种小麦旗叶保护酶相关基因表达水平的影响
Fig.4
Effects of drought stress and rehydration on expression levels of enzyme activity-related genes in flag leaves of different wheat varieties
3 讨论
干旱胁迫会诱导植物叶片衰老,导致作物光合速率降低,而耐旱品种可以维持较稳定的气孔开度和Pn。郑麦1860的气孔大小在干旱胁迫下相比于百农207和周麦18来说较大,复水后其气孔开度也能较好地恢复到干旱胁迫之前的状态,并且郑麦1860的Pn也显著高于百农207及周麦18,表明郑麦1860相较于百农207和周麦18耐旱性能更强。植物根系在吸收水分、感知水分亏缺信号并将其传递给地上部的过程中起着关键作用,较高表面积的根系可以使小麦吸收更多的水分和养分[22]。而耐旱品种往往会有更高的根冠比,从而使根部可以伸入深层土壤,以抵抗干旱胁迫对其造成的伤害[23]。Hassouni等[24]研究发现,水分胁迫下深根小麦的千粒重和产量分别增加了35%和38%。在本研究中,郑麦1860具有更高根冠比、更大根表面积以及更多根尖数,增强了其吸水能力,提高了耐旱性。并且复水后,郑麦1860的恢复效果更显著。复水后郑麦1860的Pn与CK组小麦相差最小,进一步表明复水后相比于百农207和周麦18,郑麦1860能更好地缓解干旱胁迫对其造成的伤害,这与Djanaguiraman等[23]研究结果一致。郑麦1860在干旱处理下,其千粒重、穗粒数以及产量的减少幅度均小于百农207及周麦18,表明郑麦1860具有更好的抗旱能力。
干旱胁迫会导致叶片发生脂质过氧化,MDA是脂质过氧化产物之一,因此,MDA含量可以反映植株受到脂质过氧化损伤的程度[25]。本试验中,干旱胁迫显著增加了小麦叶片中的MDA含量与细胞质膜透性,对小麦叶片造成了一定的损伤,其中周麦18受到的伤害最大(图2),这与Wei等[25]的研究结果一致。POD和SOD是抗氧化酶系统的重要成员,SOD可以将O2-. 转化为H2O2和O2,而POD和CAT则可以催化H2O2、氧化酚类和胺类化合物[20-21]。因此,植物抗氧化能力的提高,可以维持ROS大量产生与清除之间的平衡。本研究中,干旱胁迫下郑麦1860具有更高的抗氧化酶活性及抗氧化酶相关基因表达水平,使其具有更高的抗氧化能力及耐旱性,复水后郑麦1860的恢复效果相比于另外2个品种更显著,这与Zhang等[26]研究结果一致。
谷胱甘肽参与了植物的抗氧化防御系统,以GSH和GSSG形式存在[27]。AsA-GSH循环是植物抗氧化防御系统的重要组成部分,在平衡干旱胁迫下谷胱甘肽的氧化还原状态和缓解氧化损伤方面具有重要作用[28]。GSSG通过抗坏血酸―谷胱甘肽循环转化为GSH来维持细胞的还原环境,从而维持细胞内氧化还原平衡并保护质膜免受氧化[29]。Kaya等[30]发现,非生物胁迫会使小麦植株细胞内GSSG增加以及GSH/GSSG降低,补充GSH可以维持细胞内较高的GSH/GSSG以缓解氧化损伤。Song等[11]研究表明,GSH(GSH、GSSG和GSH/GSSG)的氧化还原状态与ROS水平密切相关,这证实了GSH/GSSG的提高有利于提高植物的耐旱性。本研究中,郑麦1860通过提高抗氧化酶(如SOD、POD和CAT等)的活性加快GSH的再生,维持细胞内较高的GSH/GSSG和较低的ROS水平,保持细胞膜的完整性,从而提高小麦的耐旱性,这与Zhao等[31]研究结果一致。而在干旱胁迫下郑麦1860的FeSOD、SOD-CuZn、MnSOD以及CAT的上调幅度显著高于其他2个品种,并且在复水后郑麦1860的酶相关基因表达水平与CK组的差异最小,这表明郑麦1860的耐旱性能较强。Tounsi等[32]研究发现,小麦干旱胁迫下的酶相关基因表达水平会显著提升,这与本研究结果一致。
4 结论
干旱胁迫下,郑麦1860可以通过提高SOD、POD、CAT等基因表达水平和活性,加快GSH的再生速度,维持细胞内较高的GSH/GSSG,清除干旱胁迫下产生的多余的ROS,维持细胞膜的完整性,而更高的根冠比、根表面积以及根尖数也加强了吸水能力,复水后郑麦1860的气孔孔径大小及气孔开度较大,因此,能维持较高水平的Pn,稳定千粒重、穗粒数以及产量。
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Lead (Pb), like other heavy metals, is not essentially required for optimal plant growth; however, plants uptake it from the soil, which poses an adverse effect on growth and yield. Asparagine (Asp) and thiourea (Thi) are known to assuage the negative impacts of heavy metal pollution on plant growth; however, combined application of Asp and Thi has rarely been tested to discern if it could improve wheat yield under Pb stress. Thus, this experimentation tested the role of individual and combined applications of Asp (40 mM) and Thi (400 mg/L) in improving wheat growth under lead (Pb as PbCl, 0.1 mM) stress. Lead stress significantly reduced plant growth, chlorophyll contents and photosystem system II (PSII) efficiency, whereas it increased Pb accumulation in the leaves and roots, leaf proline contents, phytochelatins, and oxidative stress related attributes. The sole or combined application of Asp and Thi increased the vital antioxidant biomolecules/enzymes, including reduced glutathione (GSH), ascorbic acid (AsA), ascorbate peroxsidase (APX), catalase (CAT), superoxide dismutase (SOD), glutathione S-transferase (GST), dehydroascorbate reductase (DHAR), and glutathione reductase (GR). Furthermore, the sole or the combined application of Asp and Thi modulated nitrogen metabolism by stimulating the activities of nitrate and nitrite reductase, glutamate synthase (GOGAT) and glutamine synthetase (GS). Asp and Thi together led to improve plant growth and vital physiological processes, but lowered down Pb accumulation compared to those by their sole application. The results suggest that Asp and Thi synergistically can improve wheat growth under Pb-toxicity.Copyright © 2022. Published by Elsevier Masson SAS.
Overexpression of a chrysanthemum transcription factor gene DgNAC1 improves drought tolerance in chrysanthemum
Superoxide dismutase (SOD) family in durum wheat: promising candidates for improving crop resilience
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