Genome-wide identification and expression profile analysis of trihelix transcription factor family genes in response to abiotic stress in sorghum [Sorghum bicolor (L.) Moench].

BACKGROUND: Transcription factors, including trihelix transcription factors, play vital roles in various growth and developmental processes and in abiotic stress responses in plants. The trihelix gene has been systematically studied in some dicots and monocots, including Arabidopsis, tomato, chrysanthemum, soybean, wheat, corn, rice, and buckwheat. However, there are no related studies on sorghum. RESULTS: In this study, a total of 40 sorghum trihelix (SbTH) genes were identified based on the sorghum genome, among which 34 were located in the nucleus, 5 in the chloroplast, 1 (SbTH38) in the cytoplasm, and 1 (SbTH23) in the extracellular membrane. Phylogenetic analysis of the SbTH genes and Arabidopsis and rice trihelix genes indicated that the genes were clustered into seven subfamilies: SIP1, GTγ, GT1, GT2, SH4, GTSb8, and orphan genes. The SbTH genes were located in nine chromosomes and none on chromosome 10. One pair of tandem duplication gene and seven pairs of segmental duplication genes were identified in the SbTH gene family. By qPCR, the expression of 14 SbTH members in different plant tissues and in plants exposed to six abiotic stresses at the seedling stage were quantified. Except for the leaves in which the genes were upregulated after only 2 h exposure to high temperature, the 12 SbTH genes were significantly upregulated in the stems of sorghum seedlings after 24 h under the other abiotic stress conditions. Among the selected genes, SbTH10/37/39 were significantly upregulated, whereas SbTH32 was significantly downregulated under different stress conditions. CONCLUSIONS: In this study, we identified 40 trihelix genes in sorghum and found that gene duplication was the main force driving trihelix gene evolution in sorghum. The findings of our study serve as a basis for further investigation of the functions of SbTH genes and providing candidate genes for stress-resistant sorghum breeding programmes and increasing sorghum yield.

The complete chloroplast genome sequence of Urtica fissa.

Urtica fissa E. Pritz is not only an important medicinal plant for rheumatism and cough relief, but it is also an important forage plant. In this study, the complete chloroplast genome of U. fissa was assembled for the first time and reported to be 146,837 base pairs (bp) long with a typical tetragonal structure and including a large single-copy of 79,657 bp, a small single-copy of 17,712 bp, and two inverted repeats of 24,734 bp each. It harbors 115 unique genes, including 70 protein-coding genes, 38 transfer RNA genes, and 7 ribosomal RNA genes. Phylogenetic analysis showed that U. fissa is closely related to Urtica lobatifolia. This study contributes to the understanding of the origin and evolution of U. fissa, as well as its genetic relationships with other species.