Identification And Gene Clone Of A Ricf Thermo-sensitive Virescent Mutant V5

A thermo-sensitive virescent rice mutant was identified from M2 of Nippobare by 60Coγradiation, temporarily named as v5 (virescent5). The leaf color of the mutant v5 is yellow at lower temperature (20～24℃) while turning to nearly normal green at higher temperature (26～30℃).1,The result of chlorophyll content measured indicated that it's enormously affected by temperature at the the prophase chlorophyll synthesis in the leaves of the v5 mutants, and the synthesis of chlorophyll a and chlorophyll b both were suppressed at 20℃to 24℃.2,The chlorophyll content and photosynthetic efficiency in leaves of the mutant at seedling stage were gradually increased as the rise of the temperature from 20℃to 24℃, but the value of NPQ (non-photochemical quenching) was decreased. By measurd the dynamic parameter of chlorophyll fluorescence (Fv/Fm,ΦPSⅡ,NPQ,qP), the result showed that the values of Fv/Fm,ΦPSⅡ,qP were correspond with the increasing controlled temperature. The value of NPQ showed the opposite trend from high to low, and both of them finally reached the same value with the wild-type plant.The photosynthetic efficiency of the mutant is basically the same as the wild-type at 24℃or higher temperature, even though the chlorophyll content of the mutant is always lower than wild-type.3,The PN result reflecting the reduce of the chlorophyll content of v5 caused the reduced PN value. While the PN value reduced of mutants was much more than the wild-type reduced. The extra reduced PN value is most likely to be used to keep the normal physiological development of v5.4,The agronomic traits showed that the yield of individual mutant was significantly lower than wild-type means the the prophase chlorophyll synthesis in the plants has important implications.5,Abnormal development of chloroplast with the reduced number of grana thylakoid membranes was observed in the mutant at seedling stage by using transmission electron microscopy technique.6,It was revealed from the genetic analysis that a single nuclear-encoded recessive gene tentatively designed as OsV5. It's responsible for the mutation and mapped on chromosome 9. A high-resolution physical map of the chromosomal region around the OsV5 gene was then constructed using F2 population (v5/Kasalath) and the gene was finally located on the region of 44.9 kb between the marker 5702-G and the marker 5702-A. The sequencing data of all the 8 candidate genes in this region indicated that a single base substitution of G-C was occurred in the third exon of the DUF3353 domain gene (LOC_Os09G21250). Since the subsequent alteration from codon TCA to TGA is the very cause of premature termination of the protein synthesis, it is very likely that the gene is OsV5 which causes the mutation of v5.7,We have transferred the 4 vectors of OsV5 to mutant by transgenic technology, and gained To transgenic plants for the functional complementation test.