Comparative proteomic analysis of autotetraploid and diploid Paulownia tomentosa reveals proteins associated with superior photosynthetic characteristics and stress adaptability in autotetraploid Paulownia

Abstract

To enlarge the germplasm resource of Paulownia plants, we used colchicine to induce autotetraploid Paulownia tomentosa, as reported previously. Compared with its diploid progenitor, autotetraploid P. tomentosa exhibits better photosynthetic characteristics and higher stress resistance. However, the underlying mechanism for its predominant characteristics has not been determined at the proteome level. In this study, isobaric tag for relative and absolute quantitation coupled with liquid chromatography-tandem mass spectrometry was employed to compare proteomic changes between autotetraploid and diploid P. tomentosa. A total of 1427 proteins were identified in our study, of which 130 proteins were differentially expressed between autotetraploid and diploid P. tomentosa. Functional analysis of differentially expressed proteins revealed that photosynthesis-related proteins and stress-responsive proteins were significantly enriched among the differentially expressed proteins, suggesting they may be responsible for the photosynthetic characteristics and stress adaptability of autotetraploid P. tomentosa. The correlation analysis between transcriptome and proteome data revealed that only 15 (11.5%) of the differentially expressed proteins had corresponding differentially expressed unigenes between diploid and autotetraploid P. tomentosa. These results indicated that there was a limited correlation between the differentially expressed proteins and the previously reported differentially expressed unigenes. This work provides new clues to better understand the superior traits in autotetraploid P. tomentosa and lays a theoretical foundation for developing Paulownia breeding strategies in the future.

Keywords: Autotetraploid; Paulownia tomentosa; Proteomics; Superior traits; iTRAQ.

Fig. 1

Comparison of morphological and physiological indexes of PT2 and PT4. a Plantlet of PT2 genotype; b plantlet of PT4 genotype; c leaf of PT2; d leaf of PT4; e the leaf length and width of PT2 and PT4; f the chlorophyll content of PT2 and PT4

Fig. 2

GO analysis of proteins identified in P. Tomentosa. 1341 proteins (93.97% of total) were divided into 50 function groups. a Biological process; b cellular component; c molecular function

Fig. 3

COG analysis of proteins identified in P. Tomentosa. 969 proteins (67.90% of total) were categorized into 23 function groups

Fig. 4

qRT-PCR analysis of 10 differentially expressed proteins selected randomly between diploid P. tomentosa and its autotetraploid. m.48523 8-hydroxygeraniol dehydrogenase, m.20714 phosphoglycerate kinase, m.49884 catalase, m.37390 proteasome subunit alpha type-7-like, m.22866 protochlorophyllide oxidoreductase 2, m.1174 33 kDa ribonucleoprotein, m.6239 ascorbate peroxidase, m.13987 chloroplast oxygen-evolving protein, m.52984 NADP-dependent malic enzyme, m.10949 PHB1. Bars represent the mean (±SD)