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Creation and Biological Character Study on Autotetraploid Raphanus Sativus L.

Author: XuWeiZuo
Tutor: ZhangShuNing
School: Nanjing Agricultural College
Course: Olericulture
Keywords: autotetraploid Raphanus Sativus L . high temperature stress isoenzymes photosynthesis microsporogenesis
CLC: S631.1
Type: Master's thesis
Year: 2006
Downloads: 129
Quote: 2
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Abstract

This paper is done on autotetraploid Raphanus Sativus L .from induction, identification, physiological and biochemical response to high temperature stress, Isoenzymes and characteristics of development of anther wall. It serves as a solid theoretical fundamental and guide of polyploid breeding of Raphanus Sativus L..1 In this experiment biennial vegetal dots of cultivar 2x radish was treated with the apical portion of seedlings with different dilute solution of colchicines. The results showed that treatment with 0.15% colchicines for 4 times yielded the highest autotetraploid rates （8.6%）. Comparison with diploid controls, prominent difference occurred in induced tetraploid and diploid in morphology. The height of tetraploid was higher, the interspace of expansion, the size of the leaves and flowers was larger, the thickness of leaf and the length of petiole were thicker than those of diploid. The size of tetraploid pollen grain was larger and varied, the size of stomatal guard cell was also larger, but the density of stomata was less. The tetraploid plants performed high-fertility and heat-tolerance under high temperature in summer. The content of nutritional substance of 4x was higher than that of 2x.2 The 4x radish seedling , heat tolerance was higher than 2x one, based on growth, shape and yield under high temperature field conditions and harm to membrane at 36℃/ 26℃temperature for 10 days. Compared with 2x radish, the 4x radish was characterized by straight, blade thicker, dark green and shorter cave. These biological characters were correlated with heat tolerance which indicated significant difference. Under the heat stress, the content of malondialdehyde （MDA） was changed both in 2x and 4x radish, although the content of 4x radish was lower than that of 2x one. soluble sugar and the leakage rate of elctrolyte were similar to that of 2x one. the activity of superoxide dismutase （SOD） , peroxidase （POD） and catalase（CAT） , the content of soluble protein and chlorohphyl in 4x radish were all higher than those in 2x one.3 Variability of superoxide dismutase （ SOD）, peroxidase （POD） and esterase （EST） isoenzymes of diploid and autotetraploid radish were studied with the use of polyacrylamide gel eletrophoresis. The result indicated that esterase （EST） isoenzyme bands of autotetraploid radish were one or two more than those of the diploid both in the nutritional growing stage and florescence; the number of peroxidase （POD） isoenzyme bands of autotetraploid was the same to that of the diploid, but the color was darker, the difference was significant: superoxide dismutase （SOD） isoenzyme bands of autotetraploid and diploid were same in nutritional growing stage, but the activity was stronger than that of the diploid in florescence.4 The characteristics related with photosynthesis were measured using diploid （03R-2） and colchicine-induced tetraploid by 03R-2 plants of radish （Raphanus Sativus L.）. The blade thick, chlorophyll content blade area of tetraploid radish were higher than that of diploid; while stomatal density decreased. Both in diploid and tetraploid radish, photosynthetic rates increased with light intensity; stomatal conductance increased slowly with light intensity; CO₂ concentrations reduced with light intensity slowly, almost reached the lowest and retained balance. But Pn, Gs and Ci in diploid were higher than those of tetraploid. Light saturation point （LSP） of tetraploid was 1960μmol·m^-2·s^-1 and the light compensation point （LCP） was 59.87μmol·m^-2·s^-1,which were higher than that of diploid.5 The cytology of the microsporogenesis and development of anther wall of diploid and tetraploid radish was studied. The result revealed that anther chamber of some of tetraploid developed abnormally, the interspace of tapetal cells increased at meiosis stage. Exine of microspore was light stained at one karyon stage, tapetal cells break down ahead of schedule.

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