Effects of different growth temperatures on growth, development, and plastid pigments metabolism of tobacco (Nicotiana tabacum L.) plants

Abstract

Background: Temperature remarkably affects the growth and metabolism of plants. Tobacco is an important cash crop, and the long-term effects of different growth temperatures (18.5, 23.5 and 28.5 °C, daily average) on growth, development and plastid pigments metabolism of tobacco plants were investigated in this study.

Results: Compared with tobacco plants grown under 23.5 °C, treatments with 18.5 and 28.5 °C inhibited the expansion of leaves. The contents of superoxide anion (O ₂^·- ), hydrogen peroxide (H₂O₂) and malonaldehyde (MDA) in the leaves were significantly increased under 28.5 °C from 0 to 60 days, which in turn accelerated the flowering and senescence of tobacco plants. By contrast, the treatment with 18.5 °C remarkably decreased O ₂^.- , H₂O₂ and MDA, and delayed the flowering and senescence. Furthermore, treatment with 18.5 °C significantly up-regulated the expression of glutamyl-tRNA reductase (Glu-TR) and magnesium chelatase (MgCH), and down-regulated the ferri chelatase (FeCH), protochlorophyllide oxidoreductase, chlorophyllase (CHLase), phaeophorbide a monooxygenase (PaO) and phytoene synthase (PSY), which further promoted the accumulation of chlorophyll (Chls) and reduced the carotenoids (Cars) in leaves. On the contrary, exposing to 28.5 °C remarkably down-regulated the Glu-TR and MgCH, and up-regulated the FeCH, CHLase, PaO and PSY, which in turn decreased the Chls and increased the Cars in tobacco leaves.

Conclusion: As compared with the plants grown under 23.5 °C, lower (18.5 °C) and higher (28.5 °C) growth temperature inhibited the growth of tobacco plants. In general, treatment with 28.5 °C accelerated the flowering and senescence of tobacco plants by enhancing the accumulation of O ₂^.- and H₂O₂ in leaves, while exposing to 18.5 °C had the opposite effects. Treatment with 18.5 °C increased the content of Chls and reduced the Cars in leaves. In contrast, Treatment with 28.5 °C decreased the Chls and increased the Cars. Moreover, both O ₂^.- and H₂O₂ took part in the breakdown of Chls in tobacco leaves to some extent. The results suggest that growth temperature could regulate growth, development, and plastid pigments metabolism, and 23.5 °C could be an optimal temperature for growth, development and metabolism of plastid pigments of tobacco plants under the experimental conditions.

Keywords: Growth and development; Growth temperature; Plastid pigments metabolism; Regulation; Tobacco plants.

Fig. 1

Different growth temperature settings in experiments

Fig. 2

Effects of different growth temperatures on leaf length (a) and width (b) of tobacco leaves. Level of significant difference: ** and * indicate significant difference at P ≤ 0.01 and P ≤ 0.05, respectively, same as the following figures

Fig. 3

Effects of different growth temperatures on contents of MDA (a) and soluble protein (b) in tobacco leaves

Fig. 4

Effects of different growth temperatures on levels of superoxide (a) and hydrogen peroxide (b) in tobacco leaves

Fig. 5

Effects of different growth temperatures on contents of Chla (a), Chlb (b) and total Chl (c) in tobacco leaves

Fig. 6

Effects of different growth temperatures on expression of Chls biosynthesis related-genes in tobacco leaves. Glu-TR (a); FeCH (b); MgCH (c); and POR (d), respectively

Fig. 7

Effects of different growth temperatures on expression of Chls degradation related-genes in tobacco leaves. CHLase (a); MDcase (b); and PaO (c), respectively

Fig. 8

Effects of different growth temperatures on content of Cars (a) and expression of PSY gene (b) in tobacco leaves