[Ghd7, a pleiotropic gene controlling flag leaf area in rice]

Photosynthesis is the unique source of energy for plant. Flag leaf contributed the majority of photosynthate after rice flowering. Ghd7 is a pleiotropic gene, which can significantly increase rice production. In order to study the genetic effects of Ghd7 on the flag leaf morphology, we made quantitative trait locus (QTL) analysis for flag leaf length (FLL), flag leaf width (FLW), and flag leaf area (FLA) using a Ghd7-BC2F2 population of 190 plants. In the BC2F2 population, the frequency distribution of FLL, FLW, and FLA were bimodal and in agreement with single Mendelian segregation ratio (3:1). FLL, FLW, and FLA were positively correlated with grains per panicle in the population. One QTL was mapped to the in-terval between markers RM3859 and C39 on chromosome 7, which explained 73.3%, 62.3%, and 71.8% of the variations for FLL, FLW, and FLA, and co-segregated with Ghd7. Two near-isogenic lines of NIL (mh7) and NIL (tq7) were devel-oped using Zhenshan 97 as the recurrent parent and Minghui 63 and Teqing as the donor parent, respectively. Both NILs significantly increased the phenotypic values of FLL, FLW, and FLA as compared with Zhenshan 97. FLL, The values of FLW and FLA for Ghd7 over-expression transgenic plants were 8.9 cm, 0.5 cm, and 17.8 cm2 larger than its recipient Heji-ang 19. These results demonstrated that Ghd7 plays an important role in controlling the flag leaf area in rice.