【作者】 程超华；

【导师】 王学德；

【作者基本信息】 浙江大学 ， 作物遗传育种学， 2004， 硕士

【摘要】 本试验以两对等基因系（超短纤维突变体Li₁及其野生型li₁，无纤维突变体fl及其野生型FL）为材料，分别研究激素及其相关酶与纤维伸长和纤维突起的关系，研究结果如下： 1．在田间条件下突变体纤维伸长受抑制的原因 与野生型比较，突变体开花9d后的纤维细胞在细胞形态学上存在异常：细胞质染色较浅，各种功能性细胞器如高尔基体、内质网等少，有较多的淀粉粒等。淀粉粒过多使得纤维伸长早期能量以淀粉粒形式储藏，而不是转化成多糖以用于纤维的继续伸长，导致突变体纤维伸长出现停滞现象。 田间条件下，突变体胚珠中的激素含量及峰谷值出现时期也有异常现象：在GA₃含量上，突变体没有明显变化，而野生型则有一个抛物线型变化；在IAA含量上，突变体在总体上低于野生型，峰值出现于其纤维伸长己基本停止的12DPA，而野生型峰值出现在纤维快速伸长的6DPA和15DPA；在ZRs含量上，突变体变化趋势虽与野生型相似，但含量只有野生型的1／15。说明突变体在田间条件下的ZRs缺乏、GA₃的变化平缓以及IAA的峰值出现时间异常均有可能是导致其纤维伸长受抑制的原因。而这种抑制作用由于离体条件下外源激素的存在而得到部分解除。 2．在离体条件下突变体纤维伸长所受抑制得到部分解除的原因 在同时含有IAA和GA₃两种激素的培养基中进行离体培养，突变体和野生型胚珠产生的纤维长度分别为3.41 mm和7.23 mm，比对照培养基内的纤维分别增长241％和85.38％，达到它们在田间自然条件下纤维长度的76％和24.3％，达到0.05％水平的显著，表明IAA与GA₃间在诱导纤维伸长上有协同促进作用，而且，这种作用对突变体的作用大于野生型高达3.1倍，即：在一定程度上能解除突变体纤维伸长受到的阻碍。但由于突变体在遗传上的缺损，外源GA₃和IAA尚不能完全解除突变体胚珠纤维伸长受到的限制。 3．激素与相关酶对突变体纤维伸长的协同作用 突变体在田间条件下，IAA峰值出现于纤维伸长停止之后，而IAA氧化酶则和野生型相似，一直保持上升趋势，峰值出现于伸长后期;离体条件下，突变体IAA含量及变化趋势均与野生型相似，呈持续土升，而IAA氧化酶却相对于野生型而一言变化趋势平缓，含量低。由此可见，突变体在离体条件下纤维伸长受抑制的部分解除，可能是由多种因子共同作用引起的，如:GA3、IAA和ZRs的较高含量和IAA氧化酶的沉默共同作用，使得突变体纤维得到突破性伸长。4.突变体胚珠在含GA3培养基内产生的纤维性愈伤组织 突变体在含GA3培养基内培养过程中，产生一种表面具有纤维状细胞的愈伤组织，出现频率约为总培养胚珠的10%。这种纤维状细胞常表现为多细胞的结构，常分布有类似田间植株茎叶等部位的色素腺体的黑点，细胞质膜处有大量的具次生壁加厚特征的微管出现。 这种多细胞纤维常发生在GA3培养基中的突变体胚珠上，说明GA3（赤霉素）促使突变体突破内在遗传因素的制约，对多细胞纤维的产生和分化有着重要的作用。推测赤霉素通过诱导某些沉默基因的表达，激发表皮细胞中己分化完成的原始纤维细胞的分裂和伸长。5.激素及相关酶对纤维突起的作用 无絮突变体之所以没有纤维突起，与突起前后其较低的内源GA3和ZRs水平有关。较低的POD和IAA氧化酶有助于纤维突起，开花前过高的IAA氧化酶则可能是抑制无絮突变体突起的因索之一。野生型开花当天较高的G凡和ZRs、较低的ABA等内源激素环境能够刺激物质和能量代谢，为纤维突起提供条件，而一IDPA和IDPA的IAA峰值的出现可能有助于纤维细胞的分化和初始伸长。更多还原

【Abstract】 Effects of phytohormones and relative enzymes on initiation and elongation of cotton fiber cells were studied by using two fiber mutants, super short fiber mutant (Lil) and fiberless mutant (fl). The results were shown as follows.1. Restriction mechanism for fiber elongation of Lil mutant grown in Held There were abnormities of ultra structure in 9 DPA fibers of Lil mutant whencompared with wild type: thinner cytoplasm, less functional organelles such as Golgi body and endoplasmic reticulum, ect, and more starch grains. Energy form was stored as starch in early period instead of transformed to polysaccharide during the fiber elongation, which might result in the stagnation of fiber elongation.In the fiber of Li/ mutant grown in field, hormone content and its peak and vale points during the elongation presented an abnormal curve. For the content of GA3, the mutant had a flat-trend change, while the wild type had a parabola change. For the content of IAA, the mutant was lower content than the wild type. After fiber elongation stopped, a peak point of IAA occurred at 12 DPA for the mutant, but had two peaks at 6 DPA and 15 DPA for the wild type, which corresponded for the dates of fiber fast elongation. For the ZRs content, although the mutant had the similar change trend to the wild type, the content was only 1/15 of the wild type. This indicated that shortage of ZRs, low increase of GA3 and abnormal peaking time of IAA might be the reasons of restriction to elongation of the mutant, and this kind of restriction could be recovered partly by exogenous hormones in culture media.2. Recovery mechanism of restriction to fiber elongation of Li 1 mutant in vitroFiber length of the mutant and the wild type were 3.41 mm and 7.23 mm in GA3+IAA media and increased significantly at 5% level than fiber in check media, which were 76% and 24.3% of the field fiber length. There was a cooperation effect between GA3 and IAA on the fiber elongation, but the effect was 3.1 times more in the mutant ovule than in the wild type ovule, suggesting that cooperation effect of the two hormones could release the restriction of fiber elongation caused by some defectsof the mutant in some degree. But the restriction of fiber elongation still could not be completely released because of the genetic inhibitory factor(s) in the mutant.3. Cooperation of hormones and enzymes on fiber elongation of the mutantIn field, IAA content in the mutant fiber peaked at the end of fiber elongation, while IAA oxidase activity maintained to rise and peak in later period of fiber elongation just like the wild type did. In vitro, IAA content increased both in mutant and wild type, while IAA oxidase activity in the mutant was more calmed than in the wild type. So it can be detected that many kinds of factors acted on the release of restriction in the mutant fiber elongation, that is, high content of GA3, IAA and ZRs, and low activity of IAA oxidase made the mutant a progress in fiber elongation.4. Fiber-like callus of mutant in BT media with GA3The mutant ovule in BT media with GA3 could produce a kind of callus covered with fiber-like cells, which occupied about 10% of all bottles. This cell was a multi-cell fiber and sometime had several black dots on its surface like glands on stem and leaf of plant in field. Many microiubules around the plasmalemma were founded in these cells after culture for 21 day, which characterized second wall deposition.This kind of multi-cells often appeared in BT media with GA3. GA3 was thought to partially break the restriction in fiber initiation in the mutant and play an important role in the multi-cell formation. It was presumed that some special genes, which kept silence in field, became activated in vitro, and stimulated the original fiber cell to further separation.5. Effect of hormones and enzymes on fiber initiationLow GA3 and ZRs content made the mutant ovule no fiber initiation. Low POD and IAA oxidase activity helped to fiber initiation of the mutant, while high IAA oxidase activit更多还原