Fine Mapping And Cloning Of A Novel Rice Nutritional Balance Gene Lcd-1

The deficiency or excess of some elements would cause the variation of rice'sphenotype,especially the phenotype of the leaf.In this study,a rice mutant was found under natural growth conditions,of which the mutant would influence some mineral nutrition's absorption,causing some lesions and even death on the leaf blade,so asnamed lcd-1(leaf cell death 1).The phenotype,physiology,and the cell deathformation mechanism of the lcd-1 were studied,and the LCD-1 was further mapped cloned.This will provide important basis for the study of the gene function as well as the growth and development of rice.Main results are as follows:1.Compared to wild type,lcd-1 was short and weak.In the growth process,its basal leaves would spontaneously produce brown necrotic spots,and further extend to the entire basal blade.In the three-leaf stage,leaf necrosis began to appear,and then accompany with the growth of plants,which would be particularly evident in the tillering stage.In the mature stage,except the leaf necrosis,it was also found that the plant height and the number of the tiller were reduced.2.Diaminobenzidine(DAB)staining indicated that H2O2 was largely accumulated in lcd-1 leaves with necrosis,suggesting that a large number of H2O2 was involved in lcd-1 PCD.The accumulation of the peroxidase was detected only in the leaf with necrosis.This result indicated that the accumulation of H2O2 induced the leaf cell death.Put in the lmmol/L and 5mmol/L H2O2,SA,the leaf of lcd-1 lost the green quickly,while the wild type was perfect except in the 5mmol/L SA.The results suggested that lcd-1 was more sensitive to H2O2 and SA.3.Genetic anaysis revealed that lcd-1 mutant was controlled by a single recessive gene.Using bulked segregant analysis(BSA)we got the linked markers-RM4-1 on chromosome 4.Then using map-based cloning strategy,LCD-1 gene was mapped in a chromosome region between two InDel markers of 1D4-3 and ID4-10.At last,the LCD-1 was fine mapped between two markers of ID4-371 and ID4-3-8,in which physical distance is 11.3 Kb.In this range there are two candidate genes,through being compared with the Nipponbare genome sequence,in which LCD-1 has a deletion(15bp).And the plants with complex genetic phenomenon also could provide some evidence for LCD-1.4.Through analysis of the LCD-1 homologous gene,LCD-1 was associated with casparian strip membrane domain proteins,and it could make the casparian strip become unnormal,and then influence the content of some mineral nutritions.This study compared analysis of the wild-type and mutant on Cd,Na,As,K,Mg,Ca,Mo,Fe and Mn contents.Among them,the contents of Fe,As,K,Mn and Na were significantly different.