Knowledge Resource Center for Ecological Environment in Arid Area
| 小麦矮秆基因Rht13对水分和氮肥的响应研究 | |
| 其他题名 | Research on the response of Rht13 genotype wheat lines to moisture and nitrogen |
| 严加坤 | |
| 出版年 | 2017 |
| 学位类型 | 博士 |
| 导师 | 张岁岐 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 过去几十年里矮秆基因在自然条件下对小麦农艺性状的影响已经得到了广泛的研究；然而在干旱的条件下，其对小麦生理性状、农艺性状及产量的影响目前还不清楚。本文以一组小麦重组自交系为材料，在室内水培、盆栽和田间条件下就不同水分条件对赤霉素敏感Rht13株系生理、生长和农艺性状进行了研究，旨在揭示Rht13基因对小麦抗旱性的影响及其机制。苗期的渗透胁迫、全生育期的大田试验（设置有无降雨两个水分条件）研究发现，在短期胁迫下，Rht13株系相比rht株系能够维持更高的净光合速率并且产生了更多的地上部生物量积累。在长期水分胁迫下，Rht13株系具有比rht株系小麦更高的籽粒产量（P<0.05）。进一步的分析显示：矮秆基因Rht13株系在拔节期净光合速率并不存在显著性优势（P>0.05），而到花后10天和17天其优势逐渐显现；花后在两种水分条件下，Rht13相比rht株系具有更高的净光合速率（P<0.05）。而对千粒重、穗长、每穗小穗数、穗粒数等农艺性状分析时发现，干旱条件下含矮秆基因Rht13株系产生了更大的千粒重及穗粒数（P<0.05）。高的花后光合对Rht13产量的提高具有直接促进作用，而Rht13的高产量与千粒重、穗粒数的提高具有显著的相关性。在两水分条件下，通过水培和盆栽试验研究了全生育期的Rht13矮秆基因对小麦根系发育的影响。结果发现，与大田产量结果相似，Rht13株系小麦在盆栽的条件下依然能够维持相比rht株系小麦更高的产量。水培实验根系分析发现，在生长期10-11时(Zadoks分期)，供水组Rht13株系根长与rht株系根长并没有显著性差异，而渗透胁迫组Rht13株系则具有比rht株系小麦更长的根系（P<0.05）；到生长期16，在两种水分条件下Rht13株系均具有比rht株系更大的根系（P<0.05）。盆栽实验发现，在拔节期2014-2015生长季，两种水分条件下Rht13的根系要略大于rht株系，而2015-2016季对照的条件下Rht13根系也是略大于rht株系根系。到开花期，我们发现Rht13株系小麦根系相比拔节期只有略微的增长，而rht株系小麦根系则出现大幅度的增长。这种拔节后的根系少量生长为小麦由营养生长向生殖生长节省了更多的能量及物质。对花后干物质转运分析发现，rht株系小麦其干物质量不断增长并没有发生花前干物质的再利用，而Rht13株系小麦则发生了明显的干物质再利用。这些特征（根系的优化的发育进程、花前干物质的转运）提供了Rht13株系除高光合之外的另一高产的基础。利用水培实验研究了在短期水分胁迫下，Rht13基因导入对小麦苗期根系吸水及渗透胁迫下维持整株水分平衡的影响发现，在短期胁迫下（1天），Rht13株系能够通过降低细胞汁液渗透势及提高根系水孔蛋白的表达来提高根系水导以提高根系吸水能力。同时Rht13株系根源化学信号作用强度更大，能够更加剧烈的降低叶片蒸腾，以维持较高的叶片相对含水量从而更好的维持整株水分平衡。这表明Rht13株系具有快速适应环境水分变化的能力。在人工气候室盆栽实验条件下的研究发现，外源赤霉素不利于小麦抗旱性的提高。并且其对Rht13株系的负影响程度要远大于rht株系小麦。在外源赤霉素施用的条件下，Rht13株系由于对赤霉素的剧烈响应，导致叶片过分的伸长， “冲淡”了叶片叶绿素含量从而降低了叶片的光合速率，进一步限制了地上部生物量的累计。矿质营养是植物生长必不可少的物质基础。之前的研究发现矮杆基因有助于磷的吸收利用而对氮素的反应还没有报道。我们利用水培实验研究了两种氮浓度条件下Rht13基因对小麦生理性状的影响。实验表明，Rht13株系在低氮的条件下能够维持相对rht株系更高的叶片（新叶和老叶）光合速率。Rht13株系老叶的衰老过程要比rht株系小麦缓慢，老叶叶片中的氮向新叶转运比rht株系迟。这样使得老叶具有相对较高的氮含量及叶绿素含量，进而使其具有更高的实际光化学效率和更高的叶片光合速率。这些优势性状直接导致Rht13株系在低氮条件下，相比rht株系小麦获得更多的整株生物量积累。上述研究结果揭示了Rht13改善小麦抗旱性的机制，对于Rht13基因在干旱半干旱区及土壤贫瘠区的小麦育种及开发利用提供了理论基础。 |
| 英文摘要 | Under natural condition, effect of dwarf genes on wheat agronomic traits has been widely studied in the past few decades. However, under drought condition, the effect of dwarf on wheat physiological traits, agronomic traits and yield remained not to be very clear. This study was employed to assess the effect of gibberellin response dwarf gene Rht13 on various characters of wheat under two contrasting moisture conditions(drought and well-watered) and to explain the mechanism of Rht13 gene in influencing grain yield.Study on introducing dwarfing genes into wheat on net photosynthetic rate was really rare and also some researches belonging to this group were conducted under the single water condition. We studied the effect of Rht13 gene on wheat photosynthetic rate(Pn) under long or short(simulated by application of 10% polyethylene glycol-6000) term drought stress. The results showed that under short-term osmotic stress, the Rht13 dwarfs could maintain higher Pn that rht lines, and achieve more aboveground biomass that rht lines (P<0.05). Under long-time drought stress, Rht13 dwarfs produced more grain yield than rht lines (P<0.05). Analysis of Pn showed that Pn of Rht13 at jointing stage had no significant advantage than that of rht lines, while at 10 and 17 days after anthesis it was higher than that of rht lines(P<0.05). And correlation analysis showed that Pn of 10 and 17 days after anthesis was significant positive correlation with grain yield. This stated that Pn after anthesis had a direct promoting role in raising the grain yield of Rht13. In another side, we also found that under drought stress Rht13 dwarf produced larger thousand kernel weight and kernels per spike (P<0.05) than rht lines and these two indexes were significant correlation with grain yield (P<0.05).To test the effect of dwarfing gene on root development, we conducted a set of experiments under osmotic and long-term drought stress. The Rht13 lines exhibited increased grain yield compared with the rht lines (P<0.05) under two water conditions and their yield was also higher than that of Rht13+Rht8 lines under drought condition. The Rht13 lines had a larger root system at the seedling stage, which provided a basis for subsequent reproductive growth. In the pot experiment, the Rht13 lines also exhibited a relatively larger root at the jointing stage, with the exception of the drought treatment of the 2015-2016 season. From jointing to anthesis, the roots of the Rht13 lines increased less than those of the others and were relatively smaller than that of rht lines at anthesis. The reduced consumption of root growth after jointing saved more matter to increase above-ground biomass rather than growing root. After anthesis, the higher remobilization of dry matter co-contributed to the increased grain yield of the Rht13 lines. These results indicate that Rht13 could potentially improve the wheat yield in rain-fed and irrigation-limited areas.Now, research about the Rht13 on wheat root water uptake was rare. Under hydroponics condition, we detect the effect of Rht13 gene on root hydraulic conductivity and whole-plant water balance. Under short-term osmotic stress, Rht 13 lines counld reduce root cell osmotic potential and improve the drought related root aquaporins’ expression to improve root hydraulic conductivity in order to improve the root water absorption. At the same time, Rht13 dwarfs seemed to had greater strength root chemical signals, and can reduce leaf transpiration more severe. So under short-term osmotic stress, Rht13 can maintain higher leaf relative water content to maintain better whole-plant water balance. This showed that Rht13 dwarfs has the ability to adapt to the environment changes quickly.To detect the relationship between GA and leaf photosynthetic rate of GAR dwarfs, we conducted an experiment in phytotron by application of exogenous GA under two contrasting water conditions. We found that exogenous GA application had no positive effect on improving wheat drought tolerance. And the exogenous GA had leaded to the excessive length growth of GAR lines, which had resulted in the decreased SPAD index under two water conditions. The SPAD had directly affected the photosynthetic, which had decreased aboveground biomass indirectly. Taking all into conclusion, we find excessive leagth growth of leaves induced decrease in SPAD is involved in exogenous GA-mediated deteriorated photosynthetic of GAR dwarfs.Mineral nutrition is essential for plants to grow. Previous studies have found that Rht gene helps the absorption of phosphorus utilization and the influence on nitrogen has not been reported. A hydroponic experiment was used to study Rht13 gene effects on wheat physiological characters under the two nitrogen conditions. Low nitrogen experiments showed that Rht13 wheat could use relatively low nitrogen to remain higher leaf photosynthetic rate (new leaves and old leaves). To detect the reason we found that the aging process of Rht13 wheat old leaves was slower than rht lines and transfer of nitrogen from old leaves to new leaves was later than rht lines. So that old leaves had relatively high nitrogen content and chlorophyll content, and had the higher actual photochemical efficiency and higher photosynthetic rate . These advantages properties directly caused Rht13 wheat under the low nitrogen condition had more whole plant biomass accumulation than rht lines.Results of this study can help us understand the effect of Rht13 genes on wheat drought resistence, and the influence on adaptive capacity to nitrogen deficiency conditions. It also provides the theory support for the application of Rht13 dwarf gene in arid and semi-arid region and barren soil area. |
| 中文关键词 | 矮杆基因 ; 根系特性 ; 干旱胁迫 ; 缺氮 ; 光合效率 |
| 英文关键词 | dwarfing gene drought stress nitrogen deficiency photosynthesis root characteristic |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 生态学 |
| 来源机构 | 中国科学院水利部水土保持研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287922 |
| 推荐引用方式 GB/T 7714 | 严加坤. 小麦矮秆基因Rht13对水分和氮肥的响应研究[D]. 中国科学院大学,2017. |
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