Rice is the staple food for half of the population worldwide. Breeders have placed efforts into improving output per unit area to fulfill the increasing demand of food. The stem branch trait of the stolon enables the common wild rice to produce new individuals through vegetative reproduction habit. However, the genetic and molecular mechanism of the stem branch, a lateral shoot arising from an axillary bud at high nodes aboveground, remains elusive.
In a study published in Agronomy, researchers from Xishuangbanna Tropical Botanical Garden (XTBG) investigated the stem branch trait of an introgression line, a cross between cultivated rice (Oryza sativa) and its wild relative, O. rufipogon.
The researchers 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.
IL-J85 with the stem branch trait discovered in the research can be transplanted to cuttings after harvest and performed with a similar yield compared with YD1, which saved the growth time and production cost.
Correlation analysis found that grain yield per plant was negatively correlated with the number of panicles; however, the number of stem branches was significantly correlated with the number of panicles.
A genotypic analysis showed that the phenotype of the stem branch in the heterozygous state was consistent with that in the homozygous state, indicating that it can be broadly used in hybrid rice production.
The results suggest that common wild rice has practical value for rice production by using the stem branch trait to fix heterosis in breeding rice varieties of vegetative reproduction.
“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,” said XU Peng of XTBG.
XU Peng Ph.D Principal Investigator
Key Laboratory of Tropical Plant Resources and Sustainable Use, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun 666303, Yunnan, China