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Title:	In vitro mutation induction of local rice varieties MRQ74 and MR269 and genetic variation assessment by ISSR molecular markers
Authors:	Ahsan A. Kadhimi (P75187)
Supervisor:	Che Radziah Che Mohd Zain, Assoc. Prof. Dr.
Keywords:	In vitro technique Local rice Mutation Molecular biology
Issue Date:	22-Jun-2017
Description:	The mutation approach combined with tissue culture can be useful tool to study drought tolerance mechanisms under in vitro conditions to enhance of rice breeding program. This study was conducted to determine the effect of gamma radiation on enhancing drought tolerant rice varieties MRQ74 and MR269 through the in vitro technique. Different doses of acute gamma rays (100-700 Gy) were applied to investigate the effects of radiation on seeds. Based on germination rate and plant height, the lethal dose (LD50) was found to be 350 Gy. Plantlets were produced by using two methods (indirect and direct). The first involved indirect in vitro plant regeneration through naked seeds being exposed to acute gamma irradiation (350 Gy) for mutation induction, and then cultured on to MS medium supplemented with different concentrations of 2, 4-D, and Kin for four weeks to produce callus. Drought stress was applied to callus under different concentrations (1.5%, 3%, 4.5%, 6%, and 7%) of Polyethylene glycol PEG (MW 6000) and the effects on the best induction of callus, fresh weight, and proline concentrations were investigated. Healthy callus were selected at highest concentrations of PEG to shoot and root formation through MS and different concentrations of growth regulators. In the second method, the seeds (which were exposed to 350 Gy irradiation) direct were cultured on a half-strength standard semi-solid MS medium, enriched with 0%, 10%, and 20% PEG. The effects of PEG, on root and shoot length, fresh and dry weights of seedlings, total chlorophyll, and carbohydrate contents and proline accumulation, were examined. The plantlets, derived directly from seeds and indirectly from callus, were successfully acclimatized with 98% efficiency in a glasshouse and grown under pot conditions to maturity (M1). Next, two rice seed mutants (M1MRQ74 and M1MR269), derived directly from seeds and indirectly from callus, were evaluated in a simulated drought condition in a greenhouse to maturity (M2). Then, the generation of M3 plantlets from M2 seeds were assessed for genetic variation based on polymorphism among the selected mutant samples for both MRQ74 and MR269. The results show that doses between 340 and 360 Gy caused a 40% reduction in seedling height. LD50 for MR269 and MRQ74 was detected at 351 and 365 Gy, respectively. The most efficient response to callusing was found at 3 mg/L 2, 4-D and 0.1 mg/L kinetin. Shoot and root formation were respectively optimized in MS + 3.0 mg/L BAP + 0.1 mg/L NAA and MS + 1.0 mg/L IBA + 0.1 mg/L 2,4-D. The highest fresh weight of callus and increase in proline enzyme concentrations were obtained through acute gamma radiation at 7% PEG strength. Plants derived from irradiated seeds had the highest mean root length, dry weight, chlorophyll, proline, and carbohydrates at 20% PEG; compared to non-irradiated plants. Furthermore, the results indicate that plants derived from callus have a higher level of drought tolerance than plants derived from seeds based on all morphological, physiological and biochemical characteristics. Assessments of genetic variation reveal significant differences between control and treated materials. We can conclude that using acute gamma irradiation on callus, and inducing stress, is an efficient approach to developing new traits in tolerant varieties. This finding may benefit rice breeders in accelerating the required time in rice breeding programs and sustaining new varieties.,Certification of Master's/Doctoral Thesis" is not available
Pages:	232
Call Number:	QH506.K333 2017 tesis
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Science and Technology / Fakulti Sains dan Teknologi

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