Analysis of full length transcriptome and resistance characteristics of Atraphaxis bracteata under drought

Abstract

Drought is one of the main environmental factors affecting plant survival and growth. Atraphaxis bracteata is a common desert plant mainly utilized in afforestation and desertification control. This study analyzed the morphological, physiological and molecular regulatory characteristics of different organs of A. bracteata under drought stress. The results showed that with the intensification of drought stress, the height, root length and leaf area of A. bracteata seedlings decreased, while the content of osmotic substances and antioxidant enzyme activity increased. Furthermore, a total of 63 907 non-redundant transcript sequences, of which 55 574 transcripts were annotated, 248 178 FLNC sequences, 107 112 high-quality consistent sequences and 291 314 CCSs were obtained from Iso-Seq. Meanwhile, a total of 2 039 AS events, 22 919 SSR, 40 404 CDS and 5 902 lncRNA were also obtained. The RNA-Seq analysis results revealed that a total of 2 821, 3 907 and 5 532 DETs were identified from roots, stems and leaves, respectively, and which had significantly enrichment in "circadian rhythm-plant" and "starch and sucrose metabolism" pathway. These results would be great significance for further research on the stress resistance of A. bracteata and these DETs function.

Keywords: Atraphaxis bracteata; Circadian rhythm-plant; Differentially expressed transcript; Drought stress; Full-length transcripts.

Fig. 1

The phenotype of A. bracteata under drought stress. (A) , (B) and (D) The effect of drought stress on the growth of A. bracteata. (B) and (E) The effect of drought stress on the roots of A. bracteata. (C) and (F) The effect of drought stress on the leaves of A. bracteata.

Fig. 2

The physiological indicators of A. bracteata under drought stress. (A) The MDA content. (B) The Pro content. (C) The SP content. (D) The activity of SOD. (E) The activity of CAT. (F) The activity of POD.

Fig. 3

The functional annotation results of the full-length transcripts of A. bracteata. (A) Statistical diagram of species classification annotated with NR of the full-length transcripts. Different colors represented different species. (B) Statistical diagram of GO annotation classification of the full-length transcripts. The horizontal axis represented GO classification, the left side of the vertical axis represented the percentage of transcripts, and the right side represented the number of transcripts. (C) Statistical diagram of KOG annotation classification of the full-length transcripts. The horizontal axis represented the classification content of KOG, and the vertical axis represented the number of transcripts.

Fig. 4

The structure analysis of the full-length transcripts of A. bracteata. (A) The length distribution diagram of prediction CDS encoded protein. (B) Density distribution statistics of different SSR types. (C) The venn diagram of lncRNA predicted by CNCI, CPAT, CPC and Pfam. (D) The prediction classification chart of transcription factors.

Fig. 5

The number analysis of DETs in different organs of A. bracteata under CK and drought treatment. (A) Statistical histogram of the number of DETs in different organs. (B) The venn diagram of DETs in different organs. (C) The cluster heat map of DETs in six samples.

Fig. 6

The function analysis of differential expressed transcripts (DETs) in different organs of A. bracteata under CK and drought treatment. (A)—(C): The KEGG annotation classification diagram of DETs. (A) CKR vs. HR24h. (B) CKS vs. HS24h. (C) CKL vs. HL24h. (D)—(F): The KEGG pathway enrichment diagram of DETs. (D) CKR vs. HR24h. (E) CKS vs. HS24h. (F) CKL vs. HL24h.

Fig.7

The qRT-PCR validation of RNA-Seq data. Note: The left vertical axis represents RNA-seq-FPKM, the right vertical axis represents qRT-PCR, and the horizontal axis represents different samples.