Cd胁迫对水稻材料根系形态特征及解剖结构的影响

【作者】 刘恒；

【导师】 王昌全； 李冰；

【作者基本信息】 四川农业大学 ， 土壤学， 2010， 硕士

【摘要】 随着现代工农业的迅速发展,土壤中Cd含量增加,土壤—植物—食品系统中的Cd污染问题日趋严重。水稻是对Cd敏感的作物,其产量和品质较易受到Cd的影响。由于根系直接与污染土壤接触,其形态解剖结构随之发生改变。目前,有关水稻在逆境胁迫下外部形态结构变化的研究较多,但对Cd胁迫下水稻材料根系形态解剖结构的比较研究还未见报道。为此,本试验以4份遗传特性和根系Cd积累能力不同的保持系、恢复系水稻育种材料为供试对象,采用水培试验结合石蜡切片技术,比较了Cd胁迫下不同水稻材料根系形态解剖结构的差异,探讨Cd胁迫对水稻根系解剖结构的伤害特点,旨在为选育低吸收低积累型水稻材料提供解剖学方面的依据。主要研究结果如下：(1)随Cd浓度升高,四份水稻材料根系Cd含量逐渐上升,材料间增幅变化各异,各处理间均达显著性差异。在不同供Cd下,保持系、恢复系水稻材料根系Cd含量均是Cd高积累型显著高于Cd低积累型,表现出各自对Cd高积累和低积累的特性,且随着Cd浓度升高和生育期推进,差异逐渐增大；整体上看,同一Cd积累型水稻根系Cd含量均是保持系明显大于恢复系,恢复系表现出较强的抗Cd性；各水稻材料随生育期的推进,根系Cd含量递增、涨幅递减。(2)水稻根系形态解剖性状值在不同Cd浓度和生育期对Cd的反应各异,材料间存在差异。低Cd水平,保持系、恢复系水稻材料根系根直径、皮层厚度、中柱直径、导管直径、大导管数均较对照有不同程度的增加,高Cd水平,则较对照有所下降；同系的Cd低积累型根系形态解剖性状值均高于Cd高积累型(形态解剖性状值高,受Cd伤害较小,表现更正常),即Cd高积累型受Cd毒害较为严重,对Cd适应性更差,抗Cd能力不如Cd低积累型；从同一Cd积累型看,在不同Cd水平下均是保持系根系形态解剖性状值低于恢复系,且前者的增、降幅度更大、稳定性更差、受Cd毒害更重,而恢复系根系对Cd的适应能力更好,具有更强的抗Cd性；就生育期而言,根系各形态解剖性状值以孕穗期最高,灌浆期次之,成熟期最低,即随水稻的成熟,各指标逐渐下降,Cd毒害逐渐加深。(3)水稻根系形态解剖结构在不同Cd浓度和生育期对Cd的反应各异,材料间变化不同。以孕穗期为例,保持系两材料在低Cd下皮层出现新生根,高积累型宜香B新生根直径较低积累型E2B更粗、染色更深；在高Cd下均发生表皮脱落、皮层破损且出现黑色斑点,高积累型宜香B表皮及皮层破损较低积累型E2B严重,出现的黑点更靠近中柱,表明低积累型E2B较高积累型宜香B受Cd迫害更轻,忍耐性更强。恢复系材料在Cd胁迫下皮层均出现新生根,低Cd下高积累型R892出现新生根较低积累型绵恢725多一条,直径也较绵恢725粗,且更靠近中柱；高Cd下高积累型R892皮层破损较低积累型绵恢725严重,表明低积累型绵恢725受Cd毒害较高积累R892轻,耐Cd性更强,即保持系、恢复系均是高积累型受Cd毒害较低积累型严重。同为高积累型材料,恢复系R892仅出现新生根,保持系宜香B不仅出现新生根、皮层严重破损、还产生黑色斑点,表明恢复系R892根系解剖结构受损较保持系宜香B轻,受Cd毒害相对轻微；同为低积累型材料,保持系E2B根系皮层出现1条新生根和少量黑色斑点,恢复系绵恢725仅有一条靠近表皮的新生根,未见黑色斑点,表明恢复系绵恢725根系解剖结构变化较保持系E2B小,表现更稳定,具有更好的抗Cd性。不同生育时期来看,灌浆期和成熟期根系形态解剖结构在Cd胁迫下表现出与孕穗期类似的规律(即高Cd下水稻材料根系受Cd毒害较低Cd下严重,保持系、恢复系均是高积累型受Cd毒害较低积累型严重,同一积累型水稻材料均是保持系受Cd毒害较恢复系严重),Cd对水稻根系解剖结构的影响以成熟期最重,灌浆期次之,孕穗期最低,而其根系的自我调节能力表现为灌浆期>孕穗期>成熟期。更多还原

【Abstract】 With the rapid development of modern industry and agriculture, the Cd content in soil has increased. As a result, the problem about the Cd content in the soil-plant-food system has been more and more serious. Rice is the Cd-sensitive crop which is vulnerable to the impact of Cd, especially on the yield and quality. As the root directly contacted the contaminated soil, the morphological and anatomical structure of the plant have been changed. At present, there are many researches about the external morphology changes of rice which is under stress. However, the comparative study about the root morphological and anatomical structure of rice which is under Cd stress has not been reported. For this reason, in this experiment,4 maintain lines and restorer lines of rice breeding copies which are different in the genetic characteristics and root Cd accumulation capacity have been the test object. Through hydroponics experiment and paraffin sections, the difference of root morphological and anatomical structure from different rice materials has been compared. The injury characteristics of rice root anatomy under the Cd stress has been investigated. The research was designed to be the anatomical basis for the rice seed selection which kind is low absorption and low accumulation. The main findings are as follows:(1)With the increase of Cd concentration, Cd content of 4 rice root increased gradually, the different changes between materials and different treatments were significant. Under different Cd concentration, maintainer, restorer root Cd content of rice materials were high accumulation-type was significantly higher than the low accumulation-type materials, demonstrated their ability of high accumulation or low on the Cd accumulation characteristics, and with the increase of Cd concentration and the promoted of growth stage, the differences increased. On the whole, both as high or low accumulation-type of rice materials, the Cd content of the maintainer line was higher than the restorer line, and restorer line had stronger capacity of anti-Cd; all rice materials with the growth stages,Cd content of roots increased and the scale of rise decreased.(2)Morphological and anatomical traits values of rice root in different growth stages and Cd concentration reacted differently to Cd,varied among the 4 tested materials.Under low Cd level, root diameter, cortex thickness, central cylinder diameter, xylem vessel diameter, the number of large xylem vessel of maintainer, restorer root of rice materials were increased at different degrees compared to control;Under high Cd level, both of them decreased at different degrees compared to control.Both as the same line materials, rice root morphological and anatomical traits values of low accumulation-type were higher than the high accumulation-type(Indicated that the morphological and anatomical traits values was higher, less stressed by Cd, showed a more normal).It was indicated when compared with low accumulation-type, high accumulation-type was more stressed by Cd,the ability of adapt to Cd toxicity even worse,with weaker capacity of anti-Cd. From the same accumulation-type to Cd, both as high or low accumulation-type of rice materials, the rice root morphological and anatomical traits values of the maintainer line was lower than the restorer line. The increase and decrease range of the maintainer line was higher than the restorer line, stability was worse than the restorer line, and root of restorer line had a better adapt ability to Cd toxicity, its means had a stronger capacity of anti-Cd. From growth stages,the morphological and anatomical traits values of rice root was booting stage highest, filling stage the second, maturity stage the lowest, with the boosting of the growth stages, all parameters decreased gradually, root affected by Cd toxicity deepen gradually.(3)Morphological and anatomical structure of rice root in different growth stages and Cd concentration reacted differently to Cd,varied among the 4 tested materials.Take booting stage for example, under low Cd level, new root appeared in the cortex of maintainer line materials. Compared with the low accumulation-type E2B, the diameter of the new root of high accumulation-type Yixiang B was thicker, and the stain was deeper; under high Cd level, epidermal off, cortex damage and dark spots appeared in both materials. Compared with the low accumulation-type E2B, the phenomenon of epidermal off, cortex damage of high accumulation-type Yixiang B were more serious, and the dark spots were closer to central cylinder. It was indicated when compared with high accumulation-type Yixiang B, low accumulation-type E2B with stronger capacity of anti-Cd, was less stressed by Cd. New root appeared at cortex in both restorer line materials, but under low Cd level, for high accumulation-type of R892, there was one more root than low accumulation-type of Mianhui 725, and the root with thicker diameter was closer to the central cylinder; under high Cd level, cortex damage of high accumulation-type R892 were more serious than the low accumulation-type Mianhui 725, which indicated that low accumulation-type Mianhui 725 was less stressed by Cd and had stronger capacity of anti-Cd.Both as high accumulation type of rice materials, just new root appeared in cortex of restorer line material R892, but in maintainer line material YixiangB, not only did new root appeare, but also serious cortex damage and dark spots appeared. It was indicated that damage to root structure of restorer line material R892 was slighter than maintainer line material YixiangB, and R892 was less affected by Cd toxicity; both as low accumulation type of rice materials, there were one new root and some dark spots appeared in root cortex of maintainer line materials E2B, but for restorer line Mianhui 725, there was only one root near by epidermis, and no dark spot was discovered. It was indicated that the changes in anatomical structure of roots in restorer line Mianhui 725 was slighter than maintainer line E2B, and restorer line Mianhui 725 had better stability and stronger capacity of anti-Cd. Look from different growth stages,the root morphological and anatomical structure of filling stage and maturity stage had the similar rules to booting stage under Cd stress(Under high Cd level,the rice root damaged by Cd were more serious than it’s under low Cd level; maintainer, restorer root of rice materials damage caused by Cd were high accumulation-type more serious than the low accumulation-type materials; both as high or low accumulation-type of rice materials, the damage caused by Cd of the maintainer line were more serious than the restorer line).The morphological and anatomical structure of rice root effected by Cd was maturity stage deepest, filling stage the second,booting stage the slightest, and root system of self-regulating capacity presented as filling stage>booting stage>maturity stage.更多还原