Genetic Analysis And Gene Mapping Of A Spgs Mutant With Short Panicle And Long Grain Shape In Rice

.Although rice plays an important role in the national economy but it also plays vital role in scientific research.Rice could serve as model crop to study monocot species due to completion of whole-genome sequencing.Since last two decades rice has gaining tremendous attention in scientific research.In recent years,as population pressures and range of social issues such as environmental degradation,genetic experts have to research for increasing rice production meeting several shortcomings.Rice yield is majorly affected by number of spike per plant,grain number per spike and grain weight.In this study Yixiang 1B was obtained via EMS mutagenesis of a short grain rice mutant spgs(short panicle and grain shape),its various agronomic characters,cytological,physiological characteristics,genetic expression analysis were focused.The results of above mentioned experiment are given below:1.Determination of main agronomic characters of spgs mutant with wild-type of YixianglB found that mutant plant height was changed slightly,tassel length was reduced significantly and number of grains per spike was also significantly reduced.In terms of seed morphology,mutant seeds grain length was increased a bit while kernel width,thousand grain weight showed varying degrees of decreases.The chalkiness and chalkiness of the mutants were significantly increased by grain appearance quality,The results of the endosperm amyloplasmic scan showed that both the mutant and the wild type amylase showed irregular polygonal shapes,but the arrangement of the starch granules was more closely compared to the wild type.2.Observation of histological and cytological analysis using electron microscopy reveled hull cell size was greatly narrowed down in mutant type.Lateral glumes paraffin analysis showed that mutant husk cell layer was thin-walled and number of cells decreased in mutant than wild type decreases,and the cells spread loosely.The outermost parenchyma cells increase the area and perimeter,and the glume grows thicker3.Wild type showed fast grain filling during 0-18 days due to more assimilation and transition of translocates in caryopsis.After 18 days wild type slowed down a little and completed its grain filling in 27 days.While spgs maintained a relative constant speed and completed its filling has 36 days.Dynamics in rice caryopsis showed that mutant spgs Caryopsis remained normal in the early stages and then gradually slowing towards maturity.4.The GA content determination:contents were determined in panicles of wild and mutant type before grain filling.The results found that the biggest difference was observed in grain filling before heading stage,GA content of mutant were doubled more than in wild type.5.Quantitative genetic expression analysis revealed that GW5,GS3,Gnla,and GW2 showed similar expression level in both wild and mutant type.While GW8 and DEP1 and EP2,FZP and TAW1 was increased and reduced in mutant respectively.6.For complementation test,by constructing two of groups of hybrid of spgs/Yixiang 1 and spgs/02428,and analysis showed in both combinations F1 plants were normal,thus the mutation was controlled by recessive gene.In F2 populations of mutant phenotypes were observed in 3:1 indicating that the mutant type SPGS recessive mononuclear gene.7.For genetic mapping of some plants from F2 populations the spgs/02428 hybrid using this 510 pairs of SSR molecular markers for polymorphism analysis.We used BSA(bulk segregation analysis)method for mixing filtering pool.Primary mapping showed that this gene is located on chromosome 4 near short arm tag Os4-122.9 around RM280.In order to further positioning analysis of target genes we do fine mapping and further narrowed down the region,will ultimately be the gene location between RM6473 and RM17679,physical distance of about was 117.2 Kb.The area consists of 18 open reading frames,the further identification of candidate genes and gene sequencing work is in progress.