Analysing the rice young panicle transcriptome reveals the gene regulatory network controlled by TRIANGULAR HULL1.

BACKGROUND: TRIANGULAR HULL1 (TH1), a member of the rice ALOG gene family, has been characterized as a rice lemma/palea-related gene. To understand the gene regulatory network that controlled by TH1, we analyzed the transcriptome from a TH1 knock out (KO) line, which was generated by CRISPR/Cas9. Our study may shed some light on the molecular mechanism of lemma/palea development.

RESULTS: We obtained 20 T0 th1-C transgenic plants by CRISPR/Cas9. Among the 20 plants, there were eight bi-allelic mutations, five homozygous mutations, three heterozygous mutations, and four Non-KO plants. By comparing with the wild type and the heterozygous knock out (KO) line, the homozygous KO lines showed defects in lemma/palea development as well as in grain filling. Further more, we studied the gene regulatory network that controlled by TH1 by comparing the transcriptome of a homozygous TH1 KO line with its Non-KO line as a control. A total of 622 genes were identified as differentially expressed genes (DEGs), of which 297 genes were significantly up-regulated while 325 genes were down-regulated. One hundred thirty eight of the DEGs were assigned to the 59 KEGG (Kyoto Encyclopedia of Genes and Genomes) pathways. Among these annotated DEGs, 15 genes were related to plant hormone signal transduction, eight genes were related to starch and sucrose metabolism. These were the two largest groups of DEGs according to the KEGG pathway analysis.

CONCLUSIONS: Our results indicated that hormone related genes and starch/sucrose metabolism related genes might act as downstream targets of TH1; they might be responsible for lemma/palea development and grain filling respectively.