Genetic Analysis and Mapping of a Thermo-sensitive White Stripe-Leaf Mutant at Seedling Stage in Rice (Oryza sativa)

A thermo-sensitive white stripe-leaf mutant (tws) was selected from the M-2 progeny of a japonica variety, Jiahua 1, treated by Co-60 y-radiation. In comparison with the wild type parent, the mutant displayed a phenotype of white stripe on the 3rd and 4th leaves, but began to turn normal green on the 5th leaf when grown at low temperatures (20 degrees C and 24 degrees C). Furthermore, the content of total chlorophyll showed an obvious decrease in the leaves with white stripe. These results suggest that the expression of the mutant trait was thermo-sensitive and correlated with the leaf age of seedlings. The genetic analysis indicated that the mutant trait was controlled by a single recessive nuclear gene, designated as tws. In addition, by using SSR markers and an F-2 segregating population derived from the cross between the tws mutant and 9311, tws was mapped between the markers MM3907 and MM3928 with a physical distance of 86 kb on rice chromosome 4.