摘要
为探究盐胁迫下外源脯氨酸对油菜生长发育的调控机制,以甘蓝型油菜为试验材料,在150 mmol/L盐胁迫下设置5个外源脯氨酸水平(0、0.25、0.5、1和2 mmol/L),探究外源脯氨酸对盐胁迫下抗氧化系统、渗透物质和离子含量的影响。结果显示:盐胁迫显著抑制油菜的生长,较低浓度(0.25 mmol/L和0.5 mmol/L)外源脯氨酸均可促进油菜的生长,相比0.25 mmol/L 外源脯氨酸,施用0.5 mmol/L对油菜长势具有较好的促进作用,能够减少叶片N
土壤盐度被认为是限制粮食产量的主要因素之一,全球约20%的可耕地面积受到盐胁迫的影响,且这一比例还在快速上
植物在面对逆境胁迫时主要的应对方式之一是通过调节渗透物质缓解细胞损伤。脯氨酸(proline,Pro)作为植物体内最有效的渗透调节物质之一,能够在植物遭受非生物胁迫时积累在植物体内,发挥渗透保护和稳定蛋白结构的作
油菜(Brassica napus L.)是我国播种面积最大的油料作物,具有良好的经济效益,同时种植油菜还能改良盐碱地土
试验在华中农业大学试验基地进行,材料为“华双4号”甘蓝型油菜,由农业农村部油菜遗传育种重点实验室提供。
挑选饱满一致的种子用去离子水浸泡4 h,置于铺有1层滤纸的培养皿中,加少量超纯水润湿,用锡箔纸包住培养皿,放入4 ℃冰箱中春化4 h,转入30 ℃恒温培养箱中黑暗培养24 h。将发芽的种子转移至纱布中培养,待初生根生长至4~5 cm,转移至4 L黑色塑料盆中培养。营养液配方采用Hoagland 和Arno
试验共设置6个处理:CK,正常营养液;S,150 mmol/L NaCl;S+0.25,150 mmol/L NaCl+0.25 mmol/L Pro; S+0.5,150 mmol/L NaCl+0.5 mmol/L Pro; S+1,150 mmol/L NaCl+1 mmol/L Pro;S+2,150 mmol/L NaCl+2 mmol/L Pro。每个处理设置3个重复,每个重复4株幼苗。先用1/4营养液培养3 d,再用1/2营养液培养3 d,之后用全量营养液培养,并进行处理,每隔3 d换1次营养液,处理16 d植株出现明显差异后收获。
1)植株生长指标测定。收获时,各处理随机选取3株植株,用超纯水清洗干净,用直尺分别测量植株株高和根长,将植株分为地上部和地下部两部分,分别称鲜质量,将植株放至信封袋中于105 ℃杀青30 min,继续在70 ℃下烘干至恒质量,称干质量。
2)N
3)脯氨酸含量测定。称取不同处理植物叶片鲜样0.5 g,用5 mL 3%磺基水杨酸进行研磨提取,沸水浴提取10 min,冷却后吸取2 mL滤液到10 mL离心管中,加入2 mL冰醋酸和2 mL酸性茚三酮试剂,沸水浴中加热30 min,冷却后加入4 mL甲苯,显色分层后于520 nm下比色。
4)抗氧化酶活性测定。称取0.5 g叶片鲜样于预冷研钵中,用5 mL pH7.8的0.05 mmol/L磷酸缓冲液和少量石英砂进行研磨提取,离心后上清液为提取液。SOD活性采用氮蓝四唑法测定;POD活性采用愈创木酚法测定;CAT活性和APX活性采用紫外吸收法测定。
5)MDA含量和H2O2含量测定。称取0.5 g叶片鲜样用5 mL 5%三氯乙酸(TCA)研磨。采用硫代巴比妥酸法测定MDA含量;采用Kamali-Andani
6)AsA和GSH含量测定。称取0.5 g叶片鲜样,用5 mL 5% TCA研磨,离心后上清液为提取液。吸取1 mL滤液于试管中,加入1 mL TCA和1 mL无水乙醇,摇匀后加入0.5 mL磷酸-乙醇溶液、1 mL红菲啰啉-乙醇溶液和0.5 mL FeCl3-乙醇溶液后于534 nm下比色测定AsA含量。吸取2 mL滤液于试管中,加入4 mL磷酸钾缓冲液和0.4 mL二硝基苯甲酸试剂,显色5 min后于412 nm波长下比色测定GSH含量。
7)可溶性蛋白与可溶性糖含量测定。可溶性蛋白含量采用考马斯亮蓝G-250测定;可溶性糖含量采用蒽酮比色法测定。
由

图1 不同浓度脯氨酸对盐胁迫下植株长势的影响
Fig. 1 The growth of plants by different treatments
处理 Treatment | 株高/cm Plant height | 根长/cm Root length | 地上部 Shoot | 地下部 Root | 总鲜质量/g Total fresh mass | 总干质量/g Total dry mass | ||
---|---|---|---|---|---|---|---|---|
鲜质量/g Fresh mass | 干质量/g Dry mass | 鲜质量/g Fresh mass | 干质量/g Dry mass | |||||
CK | 24.95a | 23.65a | 15.35a | 1.77a | 4.46a | 0.31a | 19.81a | 2.08a |
S | 13.55c | 21.67a | 6.93b | 0.58bc | 0.94cd | 0.05c | 7.87b | 0.63b |
S+0.25 | 13.90bc | 23.10a | 7.31b | 0.66bc | 1.34c | 0.09b | 8.65b | 0.75b |
S+0.5 | 15.30b | 23.75a | 7.30b | 0.70b | 2.17b | 0.11b | 9.47b | 0.81b |
S+1 | 10.93d | 16.70b | 3.39c | 0.31cd | 0.58d | 0.03c | 3.97c | 0.34c |
S+2 | 9.80d | 16.47b | 2.20c | 0.20d | 0.55d | 0.02c | 2.75c | 0.22c |
注: 数据为平均值(n=3),不同小写字母表示同一指标不同处理之间差异显著(P<0.05)。下同。Note:The data were mean(n=3). Different lowercase letters indicated that there were significant difference among different treatments (P<0.05).The same as below.
由图

图2 不同处理下植株的N
Fig. 2 N
不同小写字母表示不同处理之间差异显著(P<0.05)。下同。 Different lowercase letters indicated that there were significant difference among different treatments(P<0.05). The same as below.
对油菜N
脯氨酸是植株体内重要的渗透调节物质。由

图3 不同处理下植株的脯氨酸含量
Fig. 3 Proline content of plants by different treatments
如

图4 不同处理下植株SOD(A)、CAT(B)、POD(C)和APX(D)的活性
Fig.4 SOD(A),CAT(B),POD(C) and APX(D) activities of plants by different treatments
由
处理 Treatment | 丙二醛含量/(nmol/g) MDA content | 过氧化氢含量/(µmol/g) H2O2 content | 抗坏血酸含量/(µg/g) AsA content | 还原型谷胱甘肽含量/(µg/g) GSH content |
---|---|---|---|---|
CK | 0.72d | 1.84d | 27.28d | 342.88e |
S | 1.22a | 2.57a | 36.55b | 642.89b |
S+0.25 | 1.02c | 2.16bc | 33.17bc | 465.11cd |
S+0.5 | 1.00c | 2.06c | 32.58c | 439.18d |
S+1 | 1.07bc | 2.13bc | 33.76bc | 527.33c |
S+2 | 1.13b | 2.22b | 41.81a | 814.00a |
可溶性蛋白是植物在盐胁迫反应中积累的主要代谢物之一。如

图5 不同处理下植株可溶性蛋白(A)和可溶性糖(B)含量的对比
Fig. 5 Soluble protein(A) and soluble sugar(B) contents of plants by different treatments
可溶性糖是一种重要的渗透调节剂,可为植物的生长和发育提供能量。由
盐胁迫会抑制植物的正常生长发育,引起作物产量降低、品质下降
ROS主要包括H2O2和超氧化阴离子,能够平衡植物氧化还原过程,在胁迫环境下,植物会产生过多的ROS,引起细胞膜氧化损
植物在不利环境下会积累渗透物质进行自我保护。盐胁迫下施用0.5 mmol/L外源Pro可以提高脯氨酸与可溶性蛋白含量(
盐胁迫下过量的N
综上,盐胁迫会抑制油菜生长,施用0.5 mmol/L外源Pro能够增加油菜生物量,减少N
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