【作者】 汪月霞；

【导师】 王忠；

【作者基本信息】 扬州大学 ， 植物学， 2008， 博士

【摘要】 水稻的种子根和不定根,以及由这些根上长出的分枝根都具有明显的负向光性生长运动的现象。为了探讨水稻根负向光性的机理,本研究以扬稻六号,大粒(三寸),汕优63,日本品种的日本晴四个水稻品种为材料,前2品种主要用于水培法观察水稻根的生长,汕优63主要用于水稻根负向光性中光受体的探讨,日本晴用于cpt1基因在水稻根负向光性中的作用的研究。我们进行了施加外源化学物质或激素等对水稻根负向光性影响的试验,探讨了水稻根的负向光性中的光受体、信号组分物质、IAA运输载体蛋白cpt1基因的表达。结果如下:1稻根的负向光倾斜生长是由于根尖弯曲部的受光侧细胞的生长量大于背光侧细胞的生长量所致。2蓝紫光能显著诱导稻根负向光性,而红光无效;根冠浸提液的吸收光谱在350 nm和450 nm各有一个吸收峰;根冠中有120 KD的光受体特征的蛋白条带。推测稻根负向光性的光受体可能为蓝光受体。3不同浓度的外源试剂处理在水稻根的负向光性中分别起着调节作用。Ca2+、IP3、G蛋白、LiCl、蔗糖对水稻根负向光性运动中的信号转导都具有正调节作用;质膜H+-ATPase的浓度和pH值的均衡有利于根的负向光性运动;而H2O2促进水稻次生根的弯曲和生长,且在低浓度处理下,也促进了水稻根的负向光性的弯曲度,但却抑制了种子根的弯曲和生长。4植物生长调节剂对水稻根的负向光性有不同的影响。(1)适当浓度的ABA,GA和乙烯利对水稻根的负向光性的作用都不明显,而CTK严重抑制水稻根的负向光性和生长量;(2)生长素溶液对根的负向光性生长有显著的影响。在0～100mg·L-1的浓度范围内,随着IAA的浓度提高对根的生长、负向光性和向重性反应的抑制程度加剧。(3)不定根在光照1. 5 h后,背光侧的IAA含量明显大于向光侧,种子根的生长方向既受光的调控也受外施的IAA的调控,根尖向贴有含IAA琼脂块的一侧弯曲生长。这些结果表明光引起根尖两侧IAA含量差异是导致根负向光性的原因。5本试验探讨了cpt1基因在水稻根负向光性中的作用。发现cpt1基因的表达量与0.001 mg·L-1的IAA、1 mg·L-1的CaCl2及其抑制剂1 mg·L-1的EDTA对稻根的负向光性的效应相一致。由此推测,cpt1基因可能作为IAA载体蛋白对水稻根的负向光性运动起促进作用。更多还原

【Abstract】 From the rice root growth and curve in water culture, all the seminal roots, adventitious roots and their branched roots bent away from light. To properly study the mechanism of negative phototropism of rice root, four rice (Orysa sativa L.) varieties“Yaodaoliuhao”,“Sanlicun”(large panicle variety),“xianyou 63”(too many roots variety) and“Ribenqing”(Japonica) were used in this experiment“Yaodaoliuhao”,“Sanlicun”were used for the investigation of the rice root growth and curve in water culture,“xianyou 63”was used for the experiments of photoreceptor of negative phototropism of rice root, and“Ribenqing”(Japonica) was for the study of the effect of cpt1 gene on negative phototropism of rice root. Chemical reagent(such as CaCl2、EDTA)and hormones(IAA, TIBA, CTK, ABA,GA and ethephon)with different concentrations were applied to investigate their contribution on negative phototropism of rice root. Rurthermore, the photoreceptor, signal transduction elements and the express of cpt1 gene that encoded for IAA carrier protein during negative phototropism of rice root were invesgated, too. Some fruits were acquired after corresponding experiments as followed:1 The negative phototropic bending of the rice root was mainly due to the larger growth increment of root-tip cells of the irradiated side than that of the shaded side.2 The effect of light quality on phototropic bending could be induced prominently by blue/UV light, while not be induced by red or far-red light. Absorption spectrum of the extracted solution from rice cap had two peaks under 350nm and 450nm accordingly, and the molecular weight of the 120KD protein of the cap under unilateral light was larger than that under the dark. It suggested that the blue light receptor might be the photoreceptor might be the photoreceptor for the negative phototropism in rice root3 Ca2+, EDTA, EGTA, EB, inositol, LiCl, FC, Vanadate, CTX, PTX, H2O2, sucrose, pH with different concentrations were employed to investigate their effects on phototropic bending. From the results, Ca2+, IP3, LiCl, G protein and sucrose showed positive regulation for signal transduction during negative phototropism of rice roots; the negative phototropism of rice roots prefer proper concentration of H+-ATPase on plasma membrane and pH, or will be reversed; H2O2 had different effects on rice root for it had a positive regulation for rice lateral roots, while negative to rice primary roots. The present experiments suggested that many signal transduction during negative phototropism of rice (Oryza sativa L.) root should be attributed the coorperation of different signal transduction elements more than a single elements.4 Hormones with different concentrations were applied and it was found that they had different effects on negative phototropic bending. Results showed that (1) ABA, GA and ethephon had almost no effect on the negative phototropism of rice root, while CTK obviously inhibited the growth and negative phototropic bending of rice root. (2) The auxin (IAA) in the solution as a very prominent influencing factor, inhibited the growth, the negative phototropism and the gravitropism of rice root when the concentration of IAA increased. (3) The negative phototropic bending could be regulated by exogenous IAA as well as light, the root was induced to bend toward the site of the application, caused asymmetric growth of the root cells at the elongation zone and resulted in the bending growth. IAA concentration on the shaded side of adventitions root increased much greater 1. 5 h after the start of irradiation. The une qual lateral IAA distribution can be concluded to be the main cause for the negative phototropism of rice root.5 From the effect on the cpt1gene on the correlation of asymmetric distribution of IAA with negative phototropism of rice root we found that the negative phototropism of rice root was improved by 1 mg·L-1 CaCl2 and 0.001 mg·L-1 IAA after 24h light but constrained by 1 mg·L-1 EDTA, which is similar to the expression of cpt1 gene. It could be concluded that the asymmetric distribution of IAA was an important step on the negative phototropism of rice root, which probably be taken by CPT1 as a carrier of IAA.更多还原