缺硼胁迫对枳根系生长发育及相关基因表达的影响研究

发布时间：2018-05-18 16:00

本文选题：柑橘 + 枳　；参考：《华中农业大学》2016年博士论文

【摘要】：硼是高等植物生长发育所必需的微量元素。我国大多数柑橘种植区的土壤含硼量低,柑橘缺硼现象比较普遍。柑橘一般采用嫁接繁殖,砧木根系是柑橘对养分吸收和转运的基础,研究缺硼胁迫对砧木根系生长发育的影响对于解决柑橘生产中的缺硼问题具有重要意义。本研究选取柑橘生产上常用的砧木—枳[Poncirus trifoliate(L.)Raf.]为研究材料,采用Hogland营养液水培的方法,从形态、生理、解剖和分子几方面来研究缺硼对枳根系生长发育的影响。主要结果如下:1.缺硼对枳根系形态和解剖结构的影响缺硼处理90d,植株的主根和侧根的伸长明显受到抑制,根系表现为粗短丛枝状,根尖膨大甚至坏死,整个根系颜色加深偏老龄化,根尖伸长区和分生区的长度明显缩短,侧根往根尖靠近。缺硼植株的侧根密度和侧根原基的密度都显著大于对照。石蜡切片观察发现:缺硼导致枳根尖明显膨大变粗,细胞数量增多,细胞排列混乱无序,无法观察到明显的静止中心,根尖生长点坏死,严重时坏死细胞脱落形成空腔,有大量的维管束增生,根表皮破裂。枳根尖纵切扫描电镜观察发现,缺硼植株根尖细胞壁有增厚,细胞间隙增大,细胞排列不紧凑。透射电镜观察发现缺硼根尖细胞核靠壁固缩变形,液泡极度增大,细胞器消失,细胞壁之间的胶连瓦解,细胞壁明显加厚,细胞壁内壁有物质积累,导管内壁也有大量的物质积累。2.缺硼对枳根中细胞周期相关基因以及根系伸长相关基因表达的影响根系的生长需要两个条件:一是根尖分生区细胞不断分裂增生;二是根伸长区细胞伸长生长。因此,我们筛选了几个与细胞周期调控相关的基因PtcycA,PtcycB,PtcycD3和Ptcdc2和根系伸长相关的基因PtLRP1和PtSWP1来做表达分析,观察缺硼胁迫对它们表达模式的影响。其结果显示:细胞周期相关基因的表达模式受缺硼胁迫的影响不大。PtLRP1基因在缺硼处理18h前表达量明显上调,但缺硼处理48h后,其表达量急剧下降,且明显低于对照。PtSWP1基因表达量从缺硼处理18h开始上调表达,而且其表达量显著高于对照,最高的时候是对照的3倍以上。3.缺硼对枳根中IAA含量的影响对缺硼处理90d后的枳植株添加0.3mg/L的外源IAA,结果发现:在有外源IAA存在的情况下,缺硼植株又能重新长出很多新根。新根根尖的解剖结构与正常硼营养下的植株根尖相比,除了没有正常根尖长得匀称和成熟区更接近根尖外,其它都比较正常,都能观察到比较明显的静止中心,有明显的根冠。短期缺硼处理对枳根中束缚态硼的浓度影响不大,可溶性硼的浓度随着缺硼处理的时间延长而逐渐降低。在缺硼条件下,枳根中IAA的含量与可溶性硼的浓度有相同的下降趋势。IAA的含量在缺硼处理24h前显著升高,且明显高于对照;随着处理时间延长,到第48h后,枳根中IAA含量急剧下降,且显著低于对照根中的IAA含量。4.缺硼对枳根中IAA代谢相关基因表达的影响为了进一步明确缺硼是怎样影响枳根中IAA的含量,选择了一些IAA代谢相关的基因来做表达分析,观察缺硼对这些基因表达的影响。实验结果发现:生长素合成相关基因TAA1,TAR2,YUC3和YUC8在缺硼处理12h前明显被诱导表达,12h后这些基因的表达量显著降低,直到实验结束。这些基因的表达模式与根中IAA含量的变化一致。另外,在缺硼情况下,向基性转运蛋白基因AUX1,PIN1和PIN4的表达水平明显下调,而向顶性转运蛋白基因LAX1,ABCB1和PIN3的表达水平显著升高,说明流向根尖的IAA量减少,而从根尖向外运出的IAA量增加。
[Abstract]:Boron is a necessary trace element for the growth and development of higher plants. The boron content of the soil in most of the citrus planting areas in China is low, and the phenomenon of boron deficiency in citrus is common. The root of the citrus is the basis for the absorption and transport of the citrus. The effect of boron deficiency on the growth and development of the root of the anvil system is studied to solve the citrus students. The problem of boron deficiency in the production is of great significance. In this study, we selected the stock of orange [Poncirus trifoliate (L.) Raf.] as the research material, and used the method of Hogland nutrient solution hydroponics to study the effects of boron deficiency on the growth and development of the roots of trifoliate orange from the morphological, physiological, anatomical and molecular aspects. The main results are as follows: 1. the deficiency of boron to the trifoliate orange is the main result. The effect of root morphology and anatomical structure on 90d, the elongation of the main root and the lateral root of the plant was obviously inhibited, the root of the root showed a coarse and short branching, the root tip expanded or even necrotic. The root color deepened, the length of the root tip elongated and the sub zone shortened obviously, the lateral root was close to the root tip. The lateral root density of the boron deficient plant was the root density and the root density of the boron deficient plant. The density of the lateral root primordium was significantly greater than that of the control. The observation of paraffin section showed that the lack of boron resulted in the obvious enlargement and thickening of the root tip of the trifoliate, the number of cells increased, the cells arranged disorder and disorder, the obvious static center could not be observed, the tip of the root tip was necrotic, and the necrotic cells fall off into the cavity, and a large number of vascular bundles were proliferated and the root epidermis ruptured. It was found that the cell wall of the root tip of the boron deficient plant was thickened, the cell gap increased and the cell arrangement was not compact. The transmission electron microscope observed that the nucleus of the root apex of boron deficiency was deformed, the vacuole was greatly increased, the organelle disappeared, the cell wall was thickened and the cell wall was thickened, and the inner wall of the cell wall was accumulated. There are also a large amount of material accumulation in the inner wall of the catheter, which affects the growth of the cell cycle related genes and the expression of root elongation related genes in the root of the trifoliate orange. Two conditions are required for the growth of the root system: one is the cell proliferation in the apical sub region, and the two is the growth of the cells in the root elongation region. Therefore, we screened several regulatory phases with the cell cycle. The gene PtcycA, PtcycB, PtcycD3 and Ptcdc2 and the genes related to root elongation, PtLRP1 and PtSWP1, were used for expression analysis to observe the effect of boron deficiency on their expression patterns. The results showed that the expression pattern of cell cycle related genes was not affected by boron deficiency stress, but the expression of.PtLRP1 gene was up significantly up before the boron deficiency treated 18h. After boron deficiency, the expression of 48h decreased dramatically, and the expression of.PtSWP1 gene expression was significantly lower than that of the control 18h, and the expression amount was significantly higher than that of the control. At the highest level, the.3. deficiency was more than 3 times that of the control. The effect of.3. deficiency on the IAA content in the root of trifoliate orange was added to the exogenous IAA in the 0.3mg/L after 90d deficiency. It was found that in the presence of exogenous IAA, the boron deficient plant could grow a lot of new roots again. The anatomical structure of the root tip of the new root is more normal than the normal root tip and the mature area is closer to the root tip than that of the plant root tip under the normal boron nutrition. The short-term boron deficiency treatment had little effect on the concentration of bound boron in the root of trifoliate orange, and the concentration of soluble boron gradually decreased with the prolongation of the time of boron deficiency. In the condition of boron deficiency, the content of IAA and the concentration of soluble boron in the root of the citrus trifoliate had the same decreasing trend as the content of.IAA, which was significantly higher before the boron deficiency treatment 24h, and obviously higher than that of the boron treatment. With the prolongation of treatment time and 48h, the content of IAA in the root of trifoliate orange decreased sharply and was significantly lower than the IAA content in the control root. The effect of boron deficiency on the expression of IAA metabolism related genes in the root of trifoliate trifoliate (trifoliate orange) in order to further clarify the effect of boron deficiency on the content of IAA in the root of trifoliate trifoliate, selected some genes related to IAA metabolism and observed the expression analysis. The effect of boron deficiency on the expression of these genes. The experimental results showed that the gene TAA1, TAR2, YUC3 and YUC8 were obviously induced before 12h, and the expression of these genes decreased significantly until the end of the experiment. The expression patterns of these genes were consistent with the changes in the content of IAA in the root. In addition, in the case of boron deficiency, the gene expression pattern was in the absence of boron. The expression level of the basic transporter gene AUX1, PIN1 and PIN4 was obviously down, while the expression level of LAX1, ABCB1 and PIN3 increased significantly, indicating the decrease of IAA in the root tip and the increase of IAA from the root tip.
【学位授予单位】：华中农业大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S666

【相似文献】