Mechanism Of Rice Lcd-1(t) Mutants In Response To Different Conditions Of Stress And Inheritance Of Grain Shape Of Extra Long Grain Germplasm

The practical experience of modern rice science showed that a breakthrough achievement depends on the detection of new germplasms and the effective usage in production.With the rapid development of gene sequencing technology,the ability to investigate new mutants and specific germplasms is getting more and more powerful.It has important practical meaning to develop new germplasm resources of independent intellectual property rights.One part of this study furthered our previous work on rice leaf cell death-1(t)(lcd-1(t))mutant and extra long grain germplasm LPBG09.In order to supply more information for function analysis in future,the vegetative characteristics of the lcd-1(t)mutant were analyzed in a hydroponicsystem under a series of stresses,such as drought,nitrogen stress,phosphorus stress,potassium stress,and iron stress.The other part was about the studies on the wild type variety Nipponbare and specialty seed LPBG09.Four population(Pi,F1,P2,F2)were constructed to investigate four genetic traits of particle shape(grain length,grain width,grain length to width ratio and 1000 grain weight)using the mixed genetic model of quantitative traits in plant main gene and polygene.It would lay the foundation for quantitative trait loci(QTL)mapping and cloning of the genes controlling particle shape.Main results are as follows:In a hydroponic system,the treatments were performed under different stresses respectively.The results of phenotypic analysis showed that the rice lcd-1(t)mutant grew better than the wild type at the stage of seedling.The plant height of lcd-1(t)was higher than that of the wild type.Comparing with the wild type,the adventitious roots and lateral roots appeared much earlier,and lateral roots were longer.Meanwhile,lcd-1(t)had more lateral roots than the wild-type.But in the late stage of development it showed many differences between the lcd-1(t)mutant and the wild type in plant height,root and so on.The results of physiological analysis showed that the rice lcd-1(t)mutant had different sensitivity to the nutrient elements from the wild type,which resulted in the different vegetative development between the lcd-1(t)mutant and the wild type.The results of expression analysis on Casparian protein related genes showed that the expression levels of Os01g0836600,OsAbcg2,OsRbohF,Caps8,OsESB1-1,Casp6 and the other 6 related genes were significantly higher in the lcd-1(t)mutant than the wild type.Four grain shape characters were investigated in the genetic model of the rice extra long grain germplasm.It showed that grain width was controlled in a genetic model of additive-dominance-epistasis polygenes without major gene,and the other three traits were controlled by a pair or two pairs of the major genes.The trait of 1000-grain weight was controlled by a pair of additive-dominance major genes and additive-dominance-epistasis polygenes.The trait of grain length was controlled by two pairs of additive-dominance-epistasis major gene and additive-dominance polygenes.The trait of grain width ratio was controlled by two pairs of complete dominance major gene and additive-dominance polygenes.It indicated that LPBG09 could be used as a good parent in breeding for new super rice of high yield to produce a new variety of "long grain".