Limits...
Exogenous spermidine is enhancing tomato tolerance to salinity-alkalinity stress by regulating chloroplast antioxidant system and chlorophyll metabolism.

Li J, Hu L, Zhang L, Pan X, Hu X - BMC Plant Biol. (2015)

Bottom Line: These effects were more pronounced in seedlings of cultivar Zhongza No. 9 than cultivar Jinpengchaoguan.The effect occurred earlier in cultivar Jinpengchaoguan than in cultivar Zhongza No. 9.Exogenous spermidine also exerts positive effects at the transcription level, such as down-regulation of the expression of the chlorophyllase gene and up-regulation of the expression of the porphobilinogen deaminase gene.

View Article: PubMed Central - PubMed

Affiliation: College of Horticulture, Northwest A&F University, Yangling, 712100, Shaanxi, China. lijianming66@163.com.

ABSTRACT

Background: Salinity-alkalinity stress is known to adversely affect a variety of processes in plants, thus inhibiting growth and decreasing crop yield. Polyamines protect plants against a variety of environmental stresses. However, whether exogenous spermidine increases the tolerance of tomato seedlings via effects on chloroplast antioxidant enzymes and chlorophyll metabolism is unknown. In this study, we examined the effect of exogenous spermidine on chlorophyll synthesis and degradation pathway intermediates and related enzyme activities, as well as chloroplast ultrastructure, gene expression, and antioxidants in salinity-alkalinity-stressed tomato seedlings.

Results: Salinity-alkalinity stress disrupted chlorophyll metabolism and hindered uroorphyrinogen III conversion to protoporphyrin IX. These effects were more pronounced in seedlings of cultivar Zhongza No. 9 than cultivar Jinpengchaoguan. Under salinity-alkalinity stress, exogenous spermidine alleviated decreases in the contents of total chlorophyll and chlorophyll a and b in seedlings of both cultivars following 4 days of stress. With extended stress, exogenous spermidine reduced the accumulation of δ-aminolevulinic acid, porphobilinogen, and uroorphyrinogen III and increased the levels of protoporphyrin IX, Mg-protoporphyrin IX, and protochlorophyllide, suggesting that spermidine promotes the conversion of uroorphyrinogen III to protoporphyrin IX. The effect occurred earlier in cultivar Jinpengchaoguan than in cultivar Zhongza No. 9. Exogenous spermidine also alleviated the stress-induced increases in malondialdehyde content, superoxide radical generation rate, chlorophyllase activity, and expression of the chlorophyllase gene and the stress-induced decreases in the activities of antioxidant enzymes, antioxidants, and expression of the porphobilinogen deaminase gene. In addition, exogenous spermidine stabilized the chloroplast ultrastructure in stressed tomato seedlings.

Conclusions: The tomato cultivars examined exhibited different capacities for responding to salinity-alkalinity stress. Exogenous spermidine triggers effective protection against damage induced by salinity-alkalinity stress in tomato seedlings, probably by maintaining chloroplast structural integrity and alleviating salinity-alkalinity-induced oxidative damage, most likely through regulation of chlorophyll metabolism and the enzymatic and non-enzymatic antioxidant systems in chloroplast. Exogenous spermidine also exerts positive effects at the transcription level, such as down-regulation of the expression of the chlorophyllase gene and up-regulation of the expression of the porphobilinogen deaminase gene.

Show MeSH

Related in: MedlinePlus

Effect of exogenous Spd on chloroplast ultrastructure in tomato seedlings grown under salinity–alkalinity stress. cv. ZZ, cv. Zhongza No. 9; cv. JP, cv. Jinpengchaoguan; CK, 1/2 Hoagland’s solution; S, 75 mM saline–alkaline solution (NaCl: Na2SO4: NaHCO3: Na2CO3 = 1:9:9:1); SS, sprayed with 0.25 mM Spd and treated with 75 mM saline–alkaline solution. Data were obtained from the second expanded leaves (numbered basipetally) after salinity–alkalinity treatment for 6 days. SL, stroma lamellae; GL, grana lamellae; SG, starch grains; P, plastoglobuli. Scale bars for chloroplasts and thylakoids are 0.5 and 0.1 μm, respectively. a represents chloroplast of CK treated cv. Zhongza No.9; b represents thylakoid of CK treated cv. Zhongza No.9; c represents chloroplast of CK treated cv. Jinpengchaoguan; d represents thylakoid of CK treated cv. Jinpengchaoguan; e represents chloroplast of S treated cv. Zhongza No.9; f represents thylakoid of S treated cv. Zhongza No.9; g represents chloroplast of S treated cv. Jinpengchaoguan; h represents thylakoid of S treated cv. Jinpengchaoguan; i represents chloroplast of SS treated cv. Zhongza No.9; j represents thylakoid of SS treated cv. Zhongza No.9; k represents chloroplast of SS treated cv. Jinpengchaoguan; l represents thylakoid of SS treated cv. Jinpengchaoguan
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
getmorefigures.php?uid=PMC4696305&req=5

Fig10: Effect of exogenous Spd on chloroplast ultrastructure in tomato seedlings grown under salinity–alkalinity stress. cv. ZZ, cv. Zhongza No. 9; cv. JP, cv. Jinpengchaoguan; CK, 1/2 Hoagland’s solution; S, 75 mM saline–alkaline solution (NaCl: Na2SO4: NaHCO3: Na2CO3 = 1:9:9:1); SS, sprayed with 0.25 mM Spd and treated with 75 mM saline–alkaline solution. Data were obtained from the second expanded leaves (numbered basipetally) after salinity–alkalinity treatment for 6 days. SL, stroma lamellae; GL, grana lamellae; SG, starch grains; P, plastoglobuli. Scale bars for chloroplasts and thylakoids are 0.5 and 0.1 μm, respectively. a represents chloroplast of CK treated cv. Zhongza No.9; b represents thylakoid of CK treated cv. Zhongza No.9; c represents chloroplast of CK treated cv. Jinpengchaoguan; d represents thylakoid of CK treated cv. Jinpengchaoguan; e represents chloroplast of S treated cv. Zhongza No.9; f represents thylakoid of S treated cv. Zhongza No.9; g represents chloroplast of S treated cv. Jinpengchaoguan; h represents thylakoid of S treated cv. Jinpengchaoguan; i represents chloroplast of SS treated cv. Zhongza No.9; j represents thylakoid of SS treated cv. Zhongza No.9; k represents chloroplast of SS treated cv. Jinpengchaoguan; l represents thylakoid of SS treated cv. Jinpengchaoguan

Mentions: Typical spindle chloroplasts were observed in both tomato seedlings under CK treatment, with intact double membranes and a regular arrangement of granal and stromal thylakoids (Fig. 10a–d). Under salinity–alkalinity stress, the chloroplast structures in cv. ZZ seedlings were heavily damaged; the chloroplasts were swollen, the stroma thylakoid stack and grana thylakoid were blurred, and the lamellar structure was destroyed (Fig. 10e and f). The extent of damage to the chloroplast structures of cv. JP seedlings was less than that observed in cv. ZZ seedlings, with some stroma and grana thylakoid structures remaining completely intact (Fig. 10g and h).Fig. 10


Exogenous spermidine is enhancing tomato tolerance to salinity-alkalinity stress by regulating chloroplast antioxidant system and chlorophyll metabolism.

Li J, Hu L, Zhang L, Pan X, Hu X - BMC Plant Biol. (2015)

Effect of exogenous Spd on chloroplast ultrastructure in tomato seedlings grown under salinity–alkalinity stress. cv. ZZ, cv. Zhongza No. 9; cv. JP, cv. Jinpengchaoguan; CK, 1/2 Hoagland’s solution; S, 75 mM saline–alkaline solution (NaCl: Na2SO4: NaHCO3: Na2CO3 = 1:9:9:1); SS, sprayed with 0.25 mM Spd and treated with 75 mM saline–alkaline solution. Data were obtained from the second expanded leaves (numbered basipetally) after salinity–alkalinity treatment for 6 days. SL, stroma lamellae; GL, grana lamellae; SG, starch grains; P, plastoglobuli. Scale bars for chloroplasts and thylakoids are 0.5 and 0.1 μm, respectively. a represents chloroplast of CK treated cv. Zhongza No.9; b represents thylakoid of CK treated cv. Zhongza No.9; c represents chloroplast of CK treated cv. Jinpengchaoguan; d represents thylakoid of CK treated cv. Jinpengchaoguan; e represents chloroplast of S treated cv. Zhongza No.9; f represents thylakoid of S treated cv. Zhongza No.9; g represents chloroplast of S treated cv. Jinpengchaoguan; h represents thylakoid of S treated cv. Jinpengchaoguan; i represents chloroplast of SS treated cv. Zhongza No.9; j represents thylakoid of SS treated cv. Zhongza No.9; k represents chloroplast of SS treated cv. Jinpengchaoguan; l represents thylakoid of SS treated cv. Jinpengchaoguan
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4696305&req=5

Fig10: Effect of exogenous Spd on chloroplast ultrastructure in tomato seedlings grown under salinity–alkalinity stress. cv. ZZ, cv. Zhongza No. 9; cv. JP, cv. Jinpengchaoguan; CK, 1/2 Hoagland’s solution; S, 75 mM saline–alkaline solution (NaCl: Na2SO4: NaHCO3: Na2CO3 = 1:9:9:1); SS, sprayed with 0.25 mM Spd and treated with 75 mM saline–alkaline solution. Data were obtained from the second expanded leaves (numbered basipetally) after salinity–alkalinity treatment for 6 days. SL, stroma lamellae; GL, grana lamellae; SG, starch grains; P, plastoglobuli. Scale bars for chloroplasts and thylakoids are 0.5 and 0.1 μm, respectively. a represents chloroplast of CK treated cv. Zhongza No.9; b represents thylakoid of CK treated cv. Zhongza No.9; c represents chloroplast of CK treated cv. Jinpengchaoguan; d represents thylakoid of CK treated cv. Jinpengchaoguan; e represents chloroplast of S treated cv. Zhongza No.9; f represents thylakoid of S treated cv. Zhongza No.9; g represents chloroplast of S treated cv. Jinpengchaoguan; h represents thylakoid of S treated cv. Jinpengchaoguan; i represents chloroplast of SS treated cv. Zhongza No.9; j represents thylakoid of SS treated cv. Zhongza No.9; k represents chloroplast of SS treated cv. Jinpengchaoguan; l represents thylakoid of SS treated cv. Jinpengchaoguan
Mentions: Typical spindle chloroplasts were observed in both tomato seedlings under CK treatment, with intact double membranes and a regular arrangement of granal and stromal thylakoids (Fig. 10a–d). Under salinity–alkalinity stress, the chloroplast structures in cv. ZZ seedlings were heavily damaged; the chloroplasts were swollen, the stroma thylakoid stack and grana thylakoid were blurred, and the lamellar structure was destroyed (Fig. 10e and f). The extent of damage to the chloroplast structures of cv. JP seedlings was less than that observed in cv. ZZ seedlings, with some stroma and grana thylakoid structures remaining completely intact (Fig. 10g and h).Fig. 10

Bottom Line: These effects were more pronounced in seedlings of cultivar Zhongza No. 9 than cultivar Jinpengchaoguan.The effect occurred earlier in cultivar Jinpengchaoguan than in cultivar Zhongza No. 9.Exogenous spermidine also exerts positive effects at the transcription level, such as down-regulation of the expression of the chlorophyllase gene and up-regulation of the expression of the porphobilinogen deaminase gene.

View Article: PubMed Central - PubMed

Affiliation: College of Horticulture, Northwest A&F University, Yangling, 712100, Shaanxi, China. lijianming66@163.com.

ABSTRACT

Background: Salinity-alkalinity stress is known to adversely affect a variety of processes in plants, thus inhibiting growth and decreasing crop yield. Polyamines protect plants against a variety of environmental stresses. However, whether exogenous spermidine increases the tolerance of tomato seedlings via effects on chloroplast antioxidant enzymes and chlorophyll metabolism is unknown. In this study, we examined the effect of exogenous spermidine on chlorophyll synthesis and degradation pathway intermediates and related enzyme activities, as well as chloroplast ultrastructure, gene expression, and antioxidants in salinity-alkalinity-stressed tomato seedlings.

Results: Salinity-alkalinity stress disrupted chlorophyll metabolism and hindered uroorphyrinogen III conversion to protoporphyrin IX. These effects were more pronounced in seedlings of cultivar Zhongza No. 9 than cultivar Jinpengchaoguan. Under salinity-alkalinity stress, exogenous spermidine alleviated decreases in the contents of total chlorophyll and chlorophyll a and b in seedlings of both cultivars following 4 days of stress. With extended stress, exogenous spermidine reduced the accumulation of δ-aminolevulinic acid, porphobilinogen, and uroorphyrinogen III and increased the levels of protoporphyrin IX, Mg-protoporphyrin IX, and protochlorophyllide, suggesting that spermidine promotes the conversion of uroorphyrinogen III to protoporphyrin IX. The effect occurred earlier in cultivar Jinpengchaoguan than in cultivar Zhongza No. 9. Exogenous spermidine also alleviated the stress-induced increases in malondialdehyde content, superoxide radical generation rate, chlorophyllase activity, and expression of the chlorophyllase gene and the stress-induced decreases in the activities of antioxidant enzymes, antioxidants, and expression of the porphobilinogen deaminase gene. In addition, exogenous spermidine stabilized the chloroplast ultrastructure in stressed tomato seedlings.

Conclusions: The tomato cultivars examined exhibited different capacities for responding to salinity-alkalinity stress. Exogenous spermidine triggers effective protection against damage induced by salinity-alkalinity stress in tomato seedlings, probably by maintaining chloroplast structural integrity and alleviating salinity-alkalinity-induced oxidative damage, most likely through regulation of chlorophyll metabolism and the enzymatic and non-enzymatic antioxidant systems in chloroplast. Exogenous spermidine also exerts positive effects at the transcription level, such as down-regulation of the expression of the chlorophyllase gene and up-regulation of the expression of the porphobilinogen deaminase gene.

Show MeSH
Related in: MedlinePlus