Fine mapping of an incomplete recessive gene for leaf rolling in rice (Oryza sativa L.)

Abstract

Genetic analysis and fine mapping of genes controlling leaf rolling were conducted using two backcrossed generations (BC4F2, BC4F3) derived from a cross between QMX, a non-rolled leaf cultivar as a recurrent parent, and JZB, a rolled leaf NIL of ZB as a donor parent. Results indicated that leaf rolling was mainly controlled by an incompletely recessive major gene, namelyrl (t), and at the same time, affected by quantitative trait loci (QTLs) and/or the environment. A genetic linkage map was constructed using MAPMAKER/EXP3.0 with eight polymorphic markers on chromosome 2, which were screened by BAS method from 500 SSR markers and 15 newly developed insertion/deletion (InDel) markers. The position ofrl (t) was estimated with composite interval mapping (CIM) method using WinQTLcart2.5. Generl (t) was mapped between markers InDel 112 and RM3763, and 1.0 cM away from InDel 112 using 241 plants in BC4F2 population. To fine maprl (t), one BC4F3 line with 855 plants was generated from one semi-rolled leaf plant in BC4F2. Four new polymorphic InDel markers were developed, including InDel 112.6 and InDel 113 located between markers InDel112 and RM3763. Based on the information of recombination offered by 191 rolled leaf plants and 185 non-rolled leaf plants from the BC4F3 line, we mappedrl (t) to a 137-kb region between markers InDel 112.6 and InDel 113. Homologous gene analysis suggested thatrl (t) was probably related to the process of leaf development regulated by microRNA.