A marker line H-126, carries a genetic factor making chlorophyl mutation variagated

Genetic variegations not controlled by cytoplasmic inheritance are often conferred by the excision of a DNA transposable element. The genetic analysis of a variegated mutant could lead to the first finding of a DNA transposable element that can transpose in intact rice genome. A variegated yellow leaf (yl) mutant was obtained spontaneously in F2 of the cross between an indica native variety C-5052 and ajaponica marker line H-126. This mutant segregates variegated and stable phenotyptes. We produced a near isogenic line (NIL) showing stable yellow leaf (yl-stb) with the genetic background of the japonica variety Taichung 65 (T-65). In order to reveal the genetic factor(s) responsible for the variegation of the yellow leaf mutant, we conducted genetic analysis in the pmgenies from crosses of the yl-stb NIL with several marker lines, C-5052 and H-126. As shown in Table 1, T-65 yl-stb BC3F1 and BC4F1 plants segregate yl-v (yl-variegated) plants with frequencies of 1.7 and 0.9 %, respectively. However, all the yl-v plants that appeared in the BC3F2 and BC4F2 are vague in variegation seen only in a leaf. Near isogenic lines of yl-stb were produced from BC3F2 and BC4F2 plants. The F2 populations from crosses between T-65 yl-stb BC3F2 or BC4F2 plant and marker lines excepting those from the cross, H-126 x T-65 yl-stb BC4F2 plant, segregate normal and yl-stb plants. Contrary, the cross, H-126 x T-65 yl-stb BC4F2 plant, produced yl-v plants in addition to normal and yl-stb plants. All the yl-v plants of this cross showed clear variegations in many leaves. The frequency of yl-v to yl plants (yl-stb and yl-v) was 77.4%, suggesting that H-126 carries a dominant factor responsible for the variegation. Maekawa et al. (1998) reported that a variegated albino mutant (al-v) was obtained in the selfed progenies of revertants of yl-v plants. This suggests that the variegated albino might be caused by the same factor(s) as that for the variegated yl. In order to examine this point, an al-v plant was crossed with T-65 yl-stb BC4F2 plant. As shown in Table 2, two of four Fl plants segregated both al-v and yl-v with averaged frequencies of 70%. The other Fls did not segregate any variegated plants. This result indicates that al-v and yl-v are controlled by the same genetic factor. Accordingly, the genetic factor conferring variegation on albino and yellow leaves is surmised to be derived from H-126.

22. A marker line H-126, carries a genetic factor making chiorophyl mutation variagated M. MAEKAWA, K. Rikishi, T. MATSIJURA and K. NODA Research Institute for Bioresources, Okayama University, Kurashiki, 710-0046 Japan Genetic variegations not controlled by cytoplasmic inheritance are often conferred by the excision of a DNA transposable element. The genetic analysis of a variegated mutant could lead to the first finding of a DNA transposable element that can transpose in intact rice genome. A variegated yellow leaf (yl) mutant was obtained spontaneously in F2 of the cross between an indica native variety C-5052 and ajaponica marker line H-126. This mutant segregates variegated and stable phenotyptes. We produced a near isogenic line (NIL) showing stable yellow leaf (yl-stb) with the genetic background of the japonica variety Taichung 65 (T-65). In order to reveal the genetic factor(s) responsible for the variegation of the yellow leaf mutant, we conducted genetic analysis in the pmgenies from crosses of the yl-stb NIL with several marker lines, C-5052 and H-126. As shown in Table 1, T-65 yl-stb BC3F1 and BC4F1 plants segregate yl-v (yl-variegated) plants with frequencies of 1.7 and 0.9 %, respectively. However, all the yl-v plants that appeared in the BC3F2 and BC4F2 are vague in variegation seen only in a leaf. Near isogenic lines of yl-stb were produced from BC3F2 and BC4F2 plants. The F2 populations from crosses between T-65 yl-stb BC3F2 or BC4F2 plant and marker lines excepting those from the cross, H-126 x T-65 yl-stb BC4F2 plant, segregate normal and yl-stb plants. Contrary, the cross, H-126 x T-65 yl-stb BC4F2 plant, produced yl-v plants in addition to normal and yl-stb plants. All the yl-v plants of this cross showed clear variegations in many leaves. The frequency of yl-v to yl plants (yl-stb and yl-v) was 77.4%, suggesting that H-126 carries a dominant factor responsible for the variegation. Maekawa et al. (1998) reported that a variegated albino mutant (al-v) was obtained in the selfed progenies of revertants of yl-v plants. This suggests that the variegated albino might be caused by the same factor(s) as that for the variegated yl. In order to examine this point, an al-v plant was crossed with T-65 yl-stb BC4F2 plant. As shown in Table 2, two of four Fl plants segregated both al-v and yl-v with averaged frequencies of 70%. The other Fls did not segregate any variegated plants. This result indicates that al-v and yl-v are controlled by the same genetic factor. Accordingly, the genetic factor conferring variegation on albino and yellow leaves is surmised to be derived from H-126. References Maekawa, M., 1995. Irregular segregation of variegated chlorophyll deficiency derived from a cross between distantly related varieties in Oryza sativa L.. In Modification of Gene Expression and Non-Mendelian Inheritance, K. Oono and F. Takaiwa (eds.). MAR, Japan, p. 379-388. Maekawa, M., T. Rikiishi, T. Malsuura and K. Noda, 1998. A gene for variegated albino linked to Ig on chromosome 4. RON 15: 107-108.