摘要
为探究二烯丙基二硫(diallyl disulfide, DADS)对大白菜自毒作用的缓解效应,以大白菜品种‘金麒麟’为试验材料,利用水培试验设置6组处理:CK1(1/2 Hoagland营养液)、CK2(重茬液处理)、D1(1 μmol/L DADS+重茬液)、D5(5 μmol/L DADS+重茬液)、D10(10 μmol/L DADS+重茬液)、D15(15 μmol/L DADS+重茬液),每个处理设置12个组培瓶,每个培养瓶培养4株幼苗,共48株幼苗,测定不同处理下大白菜幼苗生长性状、生理生化指标。结果显示,施用不同浓度DADS对自毒作用下大白菜幼苗的生长均具有促进作用,以5 μmol/L DADS缓解效果最好;与CK2大白菜重茬液处理相比,D5(5 μmol/L DADS)处理大白菜幼苗的地上与地下部鲜质量分别显著增加19.42%和23.40%,根系活力显著增加45.29%,总根长和根尖数也随之增加,减轻了自毒作用对根系结构的损伤;同时叶片叶绿素含量增加;与CK2处理相比,大白菜幼苗的渗透调节物质含量明显增加,抗氧化酶SOD、POD和CAT活性分别增加30.75%、27.44%和17.68%,MDA含量显著降低20.58%;组织学染色显示,D5处理过氧化氢和超氧阴离子的积累明显减少。综上,外源施用DADS可通过降低氧化胁迫,促进根系生长,从而有效地缓解大白菜根系分泌物的自毒作用,以施加5 μmol/L DADS的缓解效应最显著。
大白菜(Brassica rapa L. ssp. pekinensis),原产于中国,栽培历史悠久,种植面积与市场销量大,是我国第二大蔬菜作
在特定时刻,植物的生长发育能与环境因子发生相互作用,化感作用(allelopathy)是指植物向环境中释放化学物质对自身或其他动植物以及微生物受体的生长发育产生有利或不利的影响,这类化学物质称作化感物
关于DADS影响黄瓜、番茄等作物的生长生理代谢过程已有相关研究,而在芸薹属蔬菜上,外源施加DADS对大白菜自毒作用缓解效应尚不清楚。为探究DADS对大白菜自毒作用的缓解效应,本研究利用水培试验,设置6组DADS浓度处理,测定各处理大白菜幼苗的生长性状、生理指标,并通过组织染色显示过氧化氢和超氧阴离子积累情况,探讨DADS对大白菜幼苗自毒作用的影响机制,以期为大白菜绿色生产提供理论依据和参考。
大白菜种子于25 ℃下催芽1 d,之后将幼芽放入PCR板孔中,将其漂浮于1/4 Hoagland营养液中进行适应性培养7 d,移入1/2 Hoagland营养液的组培瓶中,每个培养瓶装入200 mL营养液培养4株大白菜幼苗。组培瓶外包锡箔纸避光,移入组培室进行培养。培养条件设为25 ℃ 6 000 lx光照14 h/19 ℃黑暗10 h,每周调节1次pH值,使pH保持在5.8~6.5,培养20 d后,调节培养瓶中营养液至200 mL,收集大白菜水培重茬培养液备用。
催芽的大白菜植物材料在1/4 Hoagland营养液中适应性培养7 d,再使用1/2 Hoagland营养液与上述收集的重茬液分别处理5 d。之后向重茬液中加入不同浓度DADS,共设置6组处理:CK1(1/2 Hoagland营养液)、CK2(重茬液处理)、D1(1 μmol/L DADS+重茬液)、D5(5 μmol/L DADS+重茬液)、D10(10 μmol/L DADS+重茬液)、D15(15 μmol/L DADS+重茬液),每个处理设置12个组培瓶,每个培养瓶培养4株幼苗,共48株幼苗。每周调节pH值保持在5.8~6.5,期间每间隔4 d向组培瓶中加入等量1/2 Hoagland营养液。DADS处理10 d后进行取样并保存于-80 ℃冰箱中备用。
1)生长性状。将大白菜幼苗置于含少量清水的培养皿中,拍照记录植株的生长情况。测量最大叶长、最大叶宽、株幅、地上部鲜质量和地下部鲜质量,再将植株的地上部和地下部放入信封中,并置于105 ℃的烘箱中杀青20 min,之后立即降低烘箱温度,维持在75 ℃,直到样品烘干至恒质量,用电子天平称量植株地上部干质量和地下部干质量。
2)根系性状。采用氯化三苯基四氮唑(TTC)法测定根系活
3)生理性状。参照文献[
采用DAB组织化学染色法观察过氧化氢累积含
由

图1 外源DADS对自毒作用下大白菜幼苗叶片(A) 和根系(B)的影响
Fig. 1 Effects of exogenous DADS on blade (A) and rootsy(B) of Chinese cabbage seedling under autointoxication
由
处理 Treatments | 地上部鲜质量/(g/plant) Shoot fresh weight | 地上部干质量/(g/plant) Shoot dry weight | 地下部鲜质量/(g/plant) Root fresh weight | 地下部干质量/ (g/plant) Root dry weight | 株幅/cm Crown diameter | 最大叶宽/cm Maximum leaf width | 最大叶长/cm Maximum leaf length |
---|---|---|---|---|---|---|---|
CK1 | 1.521±0.072a | 0.147±0.009a | 0.123±0.005a | 0.012 4±0.000 7a | 11.470±0.369a | 3.864±0.151a | 5.089±0.184a |
CK2 | 1.133±0.044e | 0.104±0.006d | 0.094±0.006c | 0.010 2±0.000 6c | 8.821±0.167e | 2.762±1.112d | 3.679±0.106d |
D1 | 1.285±0.072bc | 0.118±0.003bc | 0.105±0.003b | 0.010 7±0.000 4bc | 10.403±0.230bc | 3.166±0.101bc | 4.280±0.093b |
D5 | 1.353±0.053b | 0.126±0.005b | 0.116±0.002a | 0.011 8±0.000 3ab | 10.833±0.274b | 3.340±0.036b | 4.459±0.077b |
D10 | 1.243±0.034cd | 0.112±0.005cd | 0.106±0.004b | 0.010 9±0.000 6bc | 10.000±0.415cd | 2.978±0.173cd | 3.945±0.147c |
D15 | 1.173±0.021de | 0.104±0.004d | 0.095±0.006c | 0.010 3±0.000 6c | 9.517±0.240d | 2.943±0.146cd | 3.848±0.079cd |
注: 表中同列各个数据后不同小写字母表示差异显著水平(P<0.05)。下同。Note:In the table, data with different lowercase letters indicated significant differences among the treatments(P<0.05). The same as below.
由

图2 各处理大白菜幼苗的根系活力(A)、总根长(B)、根表面积(C)、根体积(D)、根直径(E)、根尖数(F)、分枝数(G)和交叉数(H)
Fig. 2 Roots vitality(A),total length(B),surface area(C),volume(D),diameter(E),tips(F),forks(G) and crossings(H) of the Chinese cabbage seedling under different treatments
外源DADS处理对自毒作用下大白菜幼苗的叶绿素含量测定结果(
处理 Treatment | 叶绿素a含量 Chlorophyll a content | 叶绿素b含量 Chlorophyll b content | 类胡萝卜素含量 Carotenoid content | 叶绿素(a+b)含量 Chlorophyll (a+b) content |
---|---|---|---|---|
CK1 | 1.193±0.021a | 0.423±0.004a | 0.232±0.004a | 0.809±0.011a |
CK2 | 0.870±0.012e | 0.304±0.005e | 0.169±0.008d | 0.587±0.007e |
D1 | 0.988±0.019c | 0.350±0.008bc | 0.186±0.005c | 0.669±0.013c |
D5 | 1.035±0.035b | 0.366±0.015b | 0.198±0.006b | 0.700±0.025b |
D10 | 0.962±0.021cd | 0.338±0.008cd | 0.178±0.002cd | 0.650±0.014cd |
D15 | 0.935±0.012d | 0.326±0.002d | 0.181±0.007c | 0.631±0.007d |
由

图3 不同处理大白菜幼苗渗透调节物质和MDA含量
Fig. 3 The osmotic regulation substances and the MDA content of Chinese cabbage seedling
under different treatments
自毒作用导致CK2处理的大白菜幼苗MDA含量比CK1显著升高,而外源施用DADS均可降低MDA积累,随浓度增加呈先降后升趋势,D1、D5和D10处理的MDA含量分别比CK2处理降低了8.96%、20.58%和7.32%,其中D5处理降低最显著(
大白菜幼苗各处理抗氧化酶活性测定结果如

图4 不同处理大白菜幼苗SOD(A)、POD(B)和CAT(C)活性
Fig. 4 SOD(A),POD(B) and CAT(C) activities of Chinese cabbage seedling under different treatments
DAB组织化学染色结果(

图5 不同处理大白菜幼苗组织学染色观察
Fig. 5 The histochemical staining of Chinese cabbage seedling under different treatments
DADS作为一种生物刺激素可参与植物的整个生长周期,如通过增强植物的新陈代谢来提高生物量,诱导植物产生刺激反应,使其生长更快,尤其在逆境条件下处理效果更明
DADS与生长素的生物合成密切相关,DADS通过调控番茄和黄瓜幼苗中的生长素含量来促进细胞的有丝分裂和根系生
DADS是大蒜素分解后的有机硫化合物。许多研究表明,在受体植物叶面喷施大蒜鳞茎水浸提液、土壤添加腐熟大蒜茎或套种大蒜均可提高植物叶绿素、类胡萝卜素含量和净光合速
在抵御逆境胁迫时,植物的渗透调节能力也会提高。程
自毒物质在一定浓度下会使植物细胞内的活性氧积累增加,迫使植物细胞产生氧化应激反应,提高抗氧化酶活性来抵御逆境伤害。程
综上,适宜浓度的外源DADS对大白菜幼苗的自毒作用具有缓解效应,以施加浓度为5 μmol/L 的效果最为理想,可显著提高幼苗渗透调节物质含量和抗氧化酶活性,降低活性氧水平,并在一定程度上增加叶片叶绿素含量,促进大白菜幼苗的生长与干物质的积累,从而缓解自毒胁迫对大白菜幼苗的伤害。
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