Genetic Dissection of Stem Branch Trait and Envisioning of Fixing Heterosis by Vegetative Reproduction in Oryza rufipogon

Abstract

The stem branch trait of the stolon enables the common wild rice to produce new individuals through vegetative reproduction habit. In order to understand the genetic mechanism of stem branch character, we developed introgression lines (ILs) with the irrigated rice variety Yundao1 (YD1, Oryza sativa) as the recipient parent and Yuanjiang common wild rice (YJCWR, O. rufipogon) as the donor parent for subsequent identification of the relevant genes. An IL named IL-J85 was selected, which can originate new individuals from stem branches on stem nodes. Furthermore, the newly formed individuals can survive cutting to bear normally and produce the same yield per plant as IL-J85, which saved the growth time and production cost. Two QTLs (quantitative traits loci) related to the stem branch trait, qSBR1 and qSBR5, were first mapped on chromosomes 1 and 5. The near isogenic lines NIL-Y37 and NIL-D1 in the background of Yunjing 37 and Dianjingyou 1 were cultivated, showing the same characteristics as IL-J85. Our results provide new insights into the underlying genetic mechanism of the stem branch trait in the common wild rice and have the value of breeding utilization using vegetative reproduction to fix heterosis and breed new rice varieties with the cutting characteristic.