Genetic Analysis and Gene Mapping of a Rice White Stripe Leaf Mutant (<i>st10</i>)

Abstract

A temperature-sensitive white-stripe leaf mutant st10 was identified from rice mutant library generated by EMS mutagenesis in our previous work, which has a genomic background of elite japonica variety Nipponbare. The leaves of mutant st10 appears white-stripe fore and aft in two or three leaf stages, then the white color gradually weakens as the plant grows, leaf color returns to normal during heading stage, besides the leaf vein continuing to show white color. The white strip trait is obviously affected by temperature change. All of mutants would well exhibit their mutant traits growing under the high temperature condition, which appear white strip leaves and even full white panicles, whereas the white-stripe of leave becomes narrow and the color of panicles appears normal growing the low temperature condition. The results of genetic analysis revealed that white-stripe phenotype was controlled by a single recessive nucleic gene. The F 2 population was developed from a across between peiai64s (a male sterility line) and st10 . st10 gene was mapped in 150 kb region between marker STR19 and marker STR24 on chromosome 3. In this research we assayed the chlorophyll contents of mutant leaves growing under the temperatures at 24℃, 28℃ and 32℃, the result showed that the content of chlorophyll b and chlorophyll a were significantly reduced at the temperature of 32℃, while there is no obviously change at 24℃or at 28℃. Chlorophyll Fluorescence data revealed that maximum photosynthetic quantum capacity of the mutant was less than that of the wild-type, which would contribute the decrease of chlorophyll contents of the mutant. In this study, we constructed the genetic separate population by using Pei-Ai 64, an elite sterile line, as maternal parent and st10 mutant as paternal parent to further analyze the genetic basis, the result demonstrated that the phenotype of the mutant trait was controlled with a single recessive locus that was mapped on chromosome 3 within the 150 kb region framed between STR19 and STR 24.