| Water shortage has made drought a great challenge for the worldwide agriculture. Peanut has been our country’s important oil and commercial crop, but unfortunately, its weak drought resistance directly affects its industry development. Since the emergence rate and seedling growth of peanut are closely related to its drought resistance, it is of very practical significance for its production to determine the drought resistance and study the genetic improvement.In the experiment, we have chosen the R2002-R2146 recombinant inbred groups of peanut varieties of Huayu 22 and Sunoleic95R as test targets, and then through drought resistance identification in stages of budding and seedling, we have obtained data of aspects such as germination rate, rooting rate, fresh and dry weight and chlorophyll content and enzyme activity, which allowed us to learn about the growth and development, morphological structure, physiological and biochemical condition of the peanut group, and to select parts with strong drought resistance and parts with weak drought resistance after a systematical study and identification-we have obtained 15 strong individuals and weak ones of the same number in the experiment.Besides, the 30 individuals were sampled to study peanut genetic laws and the SSR difference between different drought resistance strains by means of extracting leaves DNAs through CTAB and amplifying them through PCR method with 8 pairs of SSR primers.1.Indoor PEG stimulation of water stress conditions is necessary and also available for selecting drought resistance, because outdoor soil cultivation under many uncertain and uncontrollable natural factors will surly produce inaccurate control of the water stress conditions, which, to a great extent, can really trouble the experiment.The indoor water cultivation and PEG stimulation of water stress not only save a lot of experiment space and personnel, materials and fund, but is simple to operate an individual controlling on one factor, which is especially true for a long-run study of crop growth in the budding and seedling stages.2.Under the water stress,roots growth in germination was restrained and its physiological activity would decrease, which was in line with a whole decrease of emergence rate, root length, rooting rate, and dry weight of roots.When the qualified standard of rooting rate ratio of the controls in germination was set at 60%, which was the lowest level to resist the drought, we found that, among the whole materials,19 individuals had the ratio of 0-60.00%, most 60.00-100.00%, while only 2 individuals had ratios more than 100.00%.And ratio between controls of the dry root weight had 0-30.00% of 10 individuals and 60.00% more of 5.In addition,99.13% of the controls had ratio of 80.00-110.00% for rooting rate showing a concentrated germination, which meant that the germination rate couldn’t reflect the drought resistance in this experiment.To sum up, root length, rooting rate and dry weight of root were available as primary indicators to identify the drought resistance in early stage-the germination stage.3.The drought resistance mechanism in peanut germination was closely related to the activity of some enzymes inside peanut.Under the PEG water stress, peanut leaves had more active SOD than usual, and the SOD content in varieties of drought resistance was sharply higher than the varieties without drought resistance, manifesting SOD activity was a significant signal of drought resistance. At the same time, the MDA content in leaves rising greatly showed that MDA signified its being hurt by water stress.4.Under the PEG water stress, the germination rates of different varieties differed from each other, and had a positive correlation with germination rooting rates.Meanwhile, there were changes of seedling height, hypocotyl length, root length, fresh and dry weight of parts and chlorophyll content; in a whole, the PEG stress increased dry weight of hypocotyl, and content of chlorophyll.These gave a proof that dry matter accumulation and morphology varied among different varieties, and it was the very reason of the discrepancies of drought resistance among varieties.5.SSR Molecular Marker is a very efficient way to analyze the genetic diversities of the recombinant inbred lines, it has advantages such as simple operation, easy augmentation and analysis and high polymorphism. The result indicated that the selected 30 recombinant inbred lines of high drought resistance had huge genetic distance with coefficient range of genetic similarity of 0.273-1.000.In conclusion, although we have obtained reliable results in the experiment, there were only 4 pairs of SSR primers used for Clustering Analysis of the amplifications of the 30 strains, and the experiment result also showed only 4 pairs of primers had the clear banding of amplification production, however, with limited detected locus, which meant more polymorphism primers were necessary to reveal other parts or the whole of the interspecific genetic mutations.So in the paper,the system clustering map is only the result of the initial steps. |
PDF Full Text Request