Table 1

Primers used in this study"

Fig. 1

Amino acid sequence alignment and domains of Saccharum calreticulin (ScCRT1) Sorghum bicolor: SbCRT1 (XP_021307591.1); Zea mays: ZmCRT1 (XP_008670080.1); Setaria italic: SiCRT1 (XP_004981159.1); Brachypodium distachyon: BdCRT1 (XP_003563166.1); Oryza sativa: OsCRT1 (XP_015628738.1); Arabidopsis thaliana: AtCRT1 (NP_176030.1). Protein residues on the black background in all of these proteins are identical. The arrows indicate the approximate positions of the three domains (N, P and C). The predicted signal peptide, conserved CRT family motifs (CRT motif 1: KHEQKLDCGGGYVKLL; CRT motif 2: IMFGPDICG), triplicate repeats (A: PXXIXDPXX KKPEXWDD; B: GXWXAXXIXNPXYK, X represents arbitrary residue) [1] and the endoplasmic reticulum retention sequence HDEL was underlined in black. The putative nuclear targeting sequence (PPKKIKDPE) was underlined in red."

Fig. 2

Phylogenetic tree analysis of ScCRT1 protein and CRT proteins from other plant species"

Fig. 3

Subcellular localization of ScCRT1 fused with YFP in the epidermal cells of N. benthamiana A: fluorescent signal of ScCRT1-YFP; B: bright field; C: merged pictures. Bar = 25 μm."

Fig. 4

Expression profile of ScCRT1 in different sugarcane tissues The error bars represent the standard error of each treatment group (n = 3). Bars superscripted by different lowercase letters are significantly different at P < 0.05."

Fig. 5

Expression profile of ScCRT1 under the infection of SCMV The error bars represent the standard error of each treatment group (n = 3). Bars superscripted by different lowercase letters are significantly different at P < 0.05."

Fig. 6

Protein-protein interactions between ScCRT1 and SCMV-6K2 by Y2H assay The positive and negative controls are yeast cotransformants with plus pNubG-Fe65 pTSU2-APP and pNubG-Fe65 plus pPR3-N, respectively. DDO+X-Gal: synthetic defined yeast minimal medium lacking Leu and Trp but plus the 5-Bromo-4-Chloro-3-Indolyl β-D-Galactopyranoside; QDO+X-Gal: synthetic defined yeast minimal medium lacking Leu, Trp, His, and Ade but plus the X-Gal."

Fig. 7

Interactions between ScCRT1 and SCMV-6K2 by BiFC assay ScCRT1 was fused to the C-terminal half of YFP, while SCMV-6K2 was fused to the N-terminal half of YFP. ScCRT1-YC and YN- SCMV-6K2 were transiently co-expressed in the epidermal cells of N. benthamiana. The fluorescent signal was monitored by confocal microscopy at 48 hours post inoculation (Bar = 25 μm)."