The Identification Of The Drought-Tolerance Of Radiation-Induced Mutant Of Upland Rice IRAT109, Gene Mapping Of A Narrow Leave Mutant(Nal8)

Dry seed samples of the upland rice variety IRAT109 were treated with y-ray irradiation that induced various types of mutants. It is supposed that mutants form a representative upland rice genotype would be useful in the theoretical researches of the drought-tolerance. Regarding the complexity of drought-tolerance and the long period for evaluation of drought tolerance we also took mutations involving important agronomical or morphological traits as our objectives of this study.Repeated experiments were conducted to evaluate the drought tolerance of the mutants in order to screen out the mutants with enhanced or reduced drought tolerance from the wild type. A mutant with narrow leaf was used to construct separation population for the preliminary maping with microsatellite markers.The main results are as follows:1. We continue to focus on 34 different materials that have different performance under the drought-stress condition. The drought evaluation was conducted based on the method and facilities of soil moisture gradient. The drought resistance coefficient showed that there are six drought-sensitive mutants. Observed the 6 materials, they are manifested as reduced the water holding capacity or increased the plant transpiration area. They are lession mimic initiation in the 07TB-157,07TB-52 and 07TB-206 are increased the tiller angle and the leaf width. From the yield components, the panicle number, spikelet fertility percentage, spikelet number per panicle and 100-grain weight are reduced in varied levels under the drought condition. The drought resistance coefficient was significantly correlated with relative effective panicle number and the relative spikelet fertility percentage, the value are 0.916** and 0.995**. The drought resistance coefficient was correlated with relative biological yield, the value was 0.839*.2. Narrow leaf mutant (nal8) showed narrow leaves, flag leaf shrinkage, smaller panicle and plant dwarfing. Observed under the microscope, the structure of the vascular bundle is normal, but the sizes of the big vascular bundle and the smaller ones are both highly significantly reduced. This is probably the cause of narrowed leaf of the mutant.Two methods are used to identified the drought-resistant ability of the nal8.1) Natural dehydration results show that the nal8's water-retention capacity is the same as IRAT109.2) Under the PEG treatment as a simulated drought experiment, the enzyme activity and osmo-regulation substance of the nal8 are similar to the wild type. When the drought stress comes, the contents of the index come up; And in the normal water conditions, the contents decreased to its original level. These show that the nal8 maintain the parents'talent of resistance.Genetic analysis of F2 populations confirmed that the mutational character was controlled by a single recessive nuclear gene. The gene was mapped between microsatellite markers RM218 and RM 14764 or RM7 on chromosome 3, with genetic distances of 2.11 cM and 2.82 cM. RM4996 was found having co-segregation with the mutation.