Fig 1.
Morphological, physiological, and biochemical changes in WZ56 and NZ2 under drought stress.
(A) WZ56 showed enhanced tolerance to drought compared to NZ2, (B-G) Comparison of parameters between control and drought-stressed plants and between WZ56 and NZ2 varieties. Parameters measured were (B) relative water content (RWC), (C) transpiration rate (Tr), (D) net photosynthesis rate (Pn), (E) instantaneous water-use efficiency (WUEi), (F) stomatal conductance (Gs), (G) intercellular CO2 concentration (Ci), (H) total chlorophyll concentration, (I) proline content, and (J) soluble sugar concentration. The asterisks indicate statistical significance between the WZ56 and NZ2 varieties. *p < 0.05, ** p < 0.01 (Student’s t-test).
Fig 2.
Principal component analysis (PCA) and partial least squares discriminant analysis (OPLS-DA) of WZ56 and NZ2 leaf metabolic profiles under control (CK) and drought stress (DS) conditions.
(A) PCA plot for all samples (GC-MS), (B) OPLS-DA score plot between CK and DS for WZ56 (GC-MS), (C) OPLS-DA score plot between CK and DS for NZ2 (GC-MS), (D) PCA plot for all samples (LC-MS), (E) OPLS-DA score plot between CK and DS for WZ56 (LC-MS), (F) OPLS-DA score plot between CK and DS for NZ2 (LC-MS).
Fig 3.
Differentially expressed metabolites (DEMs) between two sweetpotato varieties under control (CK) and drought stress (DS) conditions.
(A) Up-regulated DEMs in NZ2-DS vs. NZ2-CK, (B) Up-regulated DEMs in WZ56-DS vs. WZ56-CK, (C) Down-regulated DEMS in NZ2-DS vs. NZ2-CK, (D) Down-regulated DEMS in WZ56-DS vs. WZ56-CK, (E) Venn diagram of DEMs in WZ56 CK vs. DS, NZ2 CK vs. DS, and WZ56 vs. NZ2 DS. Detailed information about the DEMs is shown in S1 and S2 Tables.
Fig 4.
PCA and OPLS-DA analysis of metabolite profiles and DEMs functional annotations.
(A) PCA for WZ56 and NZ2 metabolite samples analyzed with GC-MS, (B) OPLS-DA for WZ56 and NZ2 metabolite samples analyzed with GC-MS, (C) PCA for WZ56 and NZ2 metabolite samples analyzed with LC-MS, (D) OPLS-DA for WZ56 and NZ2 metabolite samples analyzed with LC-MS, (E) DEMs between WZ56-DS and NZ2-DS.
Table 1.
Selected differentially expressed proteins (foldchange >4) between WZ56 and NZ2 under drought stress.
Fig 5.
The 20 most enriched biological process, cell component, and molecular function annotations in the 192 DEPs.
Fig 6.
Functional classification of the 192 DEPs in WZ56 vs. NZ2 under drought stress.
Fig 7.
Significantly enriched KEGG pathways among DEPs.
(A) KEGG pathway annotations for the 192 DEPs in WZ56 compared to NZ2 under drought stress, (B) Expression level of DEPs in the enriched pathways.
Fig 8.
Interaction network of DEPs and DEMs with KEGG pathway annotations.
Fig 9.
Antioxidant enzyme activities.
(A) POD, (B) APX, (C) CAT, (D) SOD. CK: control conditions, with soil water content kept at ~40%; DS: drought stress conditions, with soil moisture content reduced to ~ 8% over 20 days. *p < 0.05 (Student’s t-test) WZ56 vs. NZ2 variety.