Dissertation
Dissertation > Agricultural Sciences > Crop > Economic crops > Fiber crops > Cotton

Study on the Morphology, Physiology and QTLS Mapping of a Dwarf Mutant Ari1327 from Cotton (Gossypium Hirsutum L.)

Author WangXinKun
Tutor TangCanMing
School Nanjing Agricultural College
Course Crop Genetics and Breeding
Keywords Cotton (Gossypium hirsutum L.) Dwarf mutant Morphology Hormone Molecular marker correlation analysis
CLC S562
Type Master's thesis
Year 2011
Downloads 6
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Cotton is an important commercial crop. Dwarf variety is logging-resistant, and appropriate for close planting and mechanization. Dwarf variety is meaning to reducing labor intensity, improving the fertilizer utilization ratio and increasing production. Dwarf mutants not only are useful in dwarf breeding, but also are important genetic resources for studying the relationship between plant stem of growth and hormones. Aril327 (69.52 cm) is shorter(P< 0.01) than the wild type (101cm). In order to understand the dwarf mechanism of Ari1327, this paper studied the morphology, hormone content, and molecular mapping of plant height and fiber quality traits. This study will provide theory basis to its application in dwarf breeding and further research. The main results were as follows:1. Morphology and cellular research of the mutant Ari1327Ari1327 and the wild type Ari971 were compared during germination period, cotyledons period and budding period. During seed germination stage, the shoot of mutant was shorter than that of the wild type (P< 0.05). In the cotyledons period, the hypocotyls of Ari1327 was shorter than that of the wild type (P< 0.05). During budding stage, the plant height of Ari1327 accounted for 63.88% of the wild type, plant height, internode number and intermodal length of mutant were smaller or fewer than that of the wild type, in addition, the difference was very significant (p<0.01).The decrease of internode length lead to the dropping of plant height. The cell length of the antepenult internode of mutant was smaller than that of the wild type, and the difference was very significant as well (p< 0.01).The difference of lateral cell diameter was indistinctive between mutant and the wild. The reduction of internode length resulted from inhibition of cell elongation.2. The response to different kinds of hormones and the hormone content of Aril327In order to understand the hormonal defective type of Ari1327, we chose GA3, BR and IAA, relating to cell elongation and set up different concentration gradient to spray on it. Results show that GA3 promote effectively plant height, internode length and internode number to increase. After six times treatments, the plant height of Ari1327 can be restored to the wild type level. BR and IAA have no effect on Aril327, and high concentrations of IAA inhibited the plant height to increase. A regression analysis was conducted with the plant height, internode number and internode length after spraying and three kinds of hormone. The regression coefficients between GA3 and plant height, internode number and internode length are significant (P< 0.01). The regression coefficients between BR and plant height, internode number and internode length of regression coefficient value was not significant. The regression coefficients between IAA and plant height, internode length was negative, significant (P< 0.05). The regression coefficients between IAA and internode number was not significant.The content of IAA and GA3 in Ari1327 was higher than that in the wild type. Exogenous GA3 could restore the IAA content of Ari1327 to the wild type level. The mutation result in the over-expression of IAA synthetic genes. A great deal of IAA in Ari1327 lead to dwarfism.3. QTL mapping for plant height and fiber quality traits of Ari1327Cross combination was created by Ari1327 and TM-1 which was a standard genetic line for Gossypium hirsutum. QTL analysis for plant height and fiber quality traits was conducted in the F2 population of the cross. Four QTLs were identified for plant height, distributed on chromosome 3、11、14 and LG6, explaining 74.53% of the plant height variance jointly. Two QTLs were identified for fiber strength, distributing on Chr.23 and LG5, explaining 4.85% and 9.85% of the fiber strength variance. A QTL was identified for micronaire, distributing on LG3 and explaining 7.28% of the fiber micronaire variance. One QTL was identified for fiber length, fiber uniformity and fiber elongation accordingly, distributing on LG3 altogether and explaining 9.86%,28.35% and 28.26% of the variance respectively.4. Correlation analysis for plant height and fiber quality of Ari1327The correlation coefficients between plant height and fiber quality traits were all small and not significant. This indicated that fiber quality traits maybe have little relative with plant height genetically, which will provide theoretical foundation for simultaneous improvement of plant height and fiber quality in cotton breeding.

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