Morphological Characterization And Genetic Mapping Of The Mutant Gene Of A Stick-shape Panicle Mutant T1340 In Setaria Italica

The panicle structure are closely related to crop yield, therefor investigation of the panicle structure and molecular mechanism of panicle type has been a hot area of research. The phenomenon of spike barren tip of Setaria italica is caused by the top panicle degradation, thereby leading to a single lax panicle poor seed setting rate, and decreased yield per plant. In this study, the wild-type Yu1 was mutagenized by chemical mutagens ethyl methylsulfone (EMS) to obtain a stable genetic mutant line T1340. It is observed that compared with wild-type Yu1, the mutants show rod-like panicle and the number of internodes decreased resulting in shorter height and narrower leaves. Besides, there is a phenomenon of bald at the top of panicle, a significantly reduced panicle, grain density loss and poor seed set. Genetic analysis showed that the mutant trait T1340 control by a single recessive gene, the use of 200 individual plants F2 population of the mutant T1340×SSR41 will initially localize on the chromosome 4 at the physical location between 7.9M and 12.8M. Additional 120 individual plants of T1340×Jin Fen-8 F2 population were used for fine positioning and ultimately the target gene is located between the physical location of millet genome 10,397,975 and 10,418,624. The analysis combined with the result of high-throughput sequencing found that mutant T1340 at 1180 base (located on the first exon) in Si005660 coding sequence, base C mutated into base T resulting in Si005660 glutamine-318 to early termination, in which caused a series of phenotypes of mutant T1340. In addition, we compared the CDS sequence of gene Si005660 and amino acid sequence using blast. There is not yet relevant research on the model species of dicotyledonous Arabidopsis thaliana or monocotyledons related millet only the highest homology in Panicum virgatum was measured and were 76% and 71.6% respectively without functional annotation. In Sorghum bicolor homology was 62.3%,contains helicase conserved C-terminal domain and SNF2 family N- terminal domain. In the maize gene homologous to the GRMZM2G467799_T1, T2, T3, homology were 58.1%,58.1% and 43.4%, but also contains helicase conserved C-terminal domain. The gene mapping and clone of spikelet stick panicle mutant can help theinvestigation on the mechanism of panicle development, providing a new theoretical foundation for the cultivation ideal panicle high-yielding rice varieties.