| Mulberry is a perennial economic species which are widespread and have a goodadaptability to environment. In arid and semi-arid regions, drought stress is one of the mostimportant environmental stress factor limiting the growth and development of plant. Therelated molecular mechanisms of mulberry drought-resistant have an important meaning tocultivate drought-resistant varieties, increase the ability of drought resistance and amelioratethe ecological environment. In this study, we used flow cytometry to identify mulberry ploidy.It could lay the foundation for the study of mulberry gene dosage effect in the future; usingtwo-dimensional electrophoresis technology to analyze mulberry differential expressed proteinsunder drought stress. These drought resistance related proteins would contribute to theunderstanding on the mechanism of genes expression and regulation, it has an importantapplication value to improve the ability of stress resistance and promote the development of themulberry silk and ecological industry. This study was consisted of three parts:1. Flow cytometry identified mulberry ploidyThis is the first time researchers using a rapid and accurate technique to identify cellploidy of mutagenic mulberry polyploidy by using flow cytometry to detect large cell group. Inthis study, using flow cytometry identified three parts of the mulberry (leaf, bud and stem)ploidy. The results indicated that the ploidy of diploid and triploid is consistent with previousreports,403-1is a tetraploid,403-9is a triploid and the others are mixoploid which are diploidand tetraploid. This study established a rapid identification technique system of mulberryploidy. It can provide cytological evidence for studying molecular and physiologicalmechanism of mulberry autopolyploid material. Meanwhile, it will be more complicated toanalyze the mulberry polyploidy character development and gene dosage due to the mixoploid.2. The tissue culture of mulberry and changes of mulberry physiological indexes underdrought stressOptimized medium was used to breed diploid, triploid and tetraploid. Tissue cultures ofmulberry provided material for further research on gene dosage effect and the mechanism ofdrought tolerance in mulberry. This experiment used containing5%PEG6000Hoaglandnutrient solution to treat mulberries0,1,3,5,9,14days, respectively. After14days, using Hoagland nutrient solution to recover to20days. Then we determined the content of prolineand malondialdehyde.The results of physiological index changes showed that the droughtdegree of mulberry is deepening consistently as the extension of drought treatment time. Afterrewatered6days, mulberry plants got a drought relief, but not to the control physiologicallevels.3. The analysis on differential proteins of mulberry under drought stressWe used two-dimensional electrophoresis technology to analyze the changes of themulberry differentially expressed proteins under drought stress and found50proteins that aresignificant change (α=0.5) and the fold change is2by PDQuest software. Using0days as acontrol group, there are23up-regulation spots,21down-regulation spots and6fluctuation spotsin the treatment group. Using matrix assisted laser desorption ionization/time of flight/massspectrometry (MALDI-TOF–TOF) successfully identified35protein spots whichparticipate in stress defense, carbohydrate metabolism, protein metabolism and photosynthesisfour physiological process, respectively. There are three spots are unknown. The analysis ofprotein function shows that the improved drought-resistant of mulberry is by the way ofregulating the carbohydrate metabolism, photosynthesis and increasing the stress defenseprotein synthesis. |
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