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Physiological and proteomic responses of diploid and tetraploid black locust (Robinia pseudoacacia L.) subjected to salt stress.

Wang Z, Wang M, Liu L, Meng F - Int J Mol Sci (2013)

Bottom Line: The results showed that diploid (2×) plants suffered from greater negative effects than those of tetraploid (4×) plants.In addition, salt stress resulted in distorted chloroplasts, swollen thylakoid membranes, accumulation of plastoglobules, and increased starch grains in 2× compared to those in 4×.Collectively, our results suggest that the plants showed significantly different responses to salt stress based on ploidy level of the plant.

View Article: PubMed Central - PubMed

Affiliation: College of Life Science, Northeast Forestry University, Harbin 150040, China. mfj19751@163.com.

ABSTRACT
Tetraploid black locust (Robinia pseudoacacia L.) is adaptable to salt stress. Here, we compared morphological, physiological, ultrastructural, and proteomic traits of leaves in tetraploid black locust and its diploid relatives under salt stress. The results showed that diploid (2×) plants suffered from greater negative effects than those of tetraploid (4×) plants. After salt treatment, plant growth was inhibited, photosynthesis was reduced, reactive oxygen species, malondialdehyde content, and relative electrolyte leakage increased, and defense-related enzyme activities decreased in 2× compared to those in 4×. In addition, salt stress resulted in distorted chloroplasts, swollen thylakoid membranes, accumulation of plastoglobules, and increased starch grains in 2× compared to those in 4×. However, 4× developed diverse responses under salt stress. A comparative proteomic analysis revealed that 41 and 37 proteins were differentially expressed in 2× and 4×, respectively. These proteins were mainly involved in photosynthesis, stress and defense, energy, metabolism, transcription/translation, and transportation. Distinct patterns of protein changes between 2× and 4× were analyzed. Collectively, our results suggest that the plants showed significantly different responses to salt stress based on ploidy level of the plant. The 4× possessed a better salt protection mechanism than that of 2×, suggesting salt tolerance in the polyploid plant.

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Transmission electron micrographs of diploid (2×) and tetraploid (4×) Robinia pseudoacacia mesophyll cells after one day and 10 days of salt treatment. (A) 0 day, 2×; (B) 0 day, 4×; (C) 10 days, 2×; (D) 10 days, 4×. CW, cell wall; Ch, chloroplast; M, mitochondrion; Nu, nucleolus; P, plastoglobule; SG, starch granule; Gr, granum; V, vacuole; Vs, small vesicle.
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f7-ijms-14-20299: Transmission electron micrographs of diploid (2×) and tetraploid (4×) Robinia pseudoacacia mesophyll cells after one day and 10 days of salt treatment. (A) 0 day, 2×; (B) 0 day, 4×; (C) 10 days, 2×; (D) 10 days, 4×. CW, cell wall; Ch, chloroplast; M, mitochondrion; Nu, nucleolus; P, plastoglobule; SG, starch granule; Gr, granum; V, vacuole; Vs, small vesicle.

Mentions: The results for the physiological responses of plant growth to salt stress were different (Figures 1–8). Salt stress inhibited plant growth and decreased net photosynthetic rate and stomatal conductance in 2×. However, the decreases in these parameters were less in 4× than those in 2×. These results agree with our earlier research showing that 4× plants are relatively salt-tolerant compared to that of 2× plants [24]. Similar results were reported by another group [25]. In Figure 5, our results showed that Pn and Gs for 4× were not sensitive in response to salt stress after RWC decreases are detectable. It may be a reason that the salt stress caused less pronounced inhibition of photosynthesis in 4× than in 2×. In other words, 4× plants have higher water use efficiency under salt stress. Thus, 4× can keep photosynthesis stability under low RWC to adapt salt stress. At the same time, RWC is not only factor influencing Pn. The decrease in growth and stomatal conductance may result from reduced leaf water content. Gs plays an important role in the change in Pn. Little change in Ci was observed compared with that of Gs (Figure 3). This indicates that photosynthesis under salt stress may be affected by other factors such as the availability of ATP and Rubisco activity [26]. The changes between Pn, Gs, and Ci in 2× and 4× plants were different, which was further supported by the proteomics results. The expression levels of 19 and 16 proteins including Rubisco large subunit, rubisco activase and ATP synthase CF1 alpha subunit increased in 2× and 4× after salt treatment, respectively. MDA and REL are important indicators of the damage caused by salt stress [27]. The present results show that salinity significantly increased MDA content and REL in 2× more than those in 4×, indicating more damage to membranes in 2× plants.


Physiological and proteomic responses of diploid and tetraploid black locust (Robinia pseudoacacia L.) subjected to salt stress.

Wang Z, Wang M, Liu L, Meng F - Int J Mol Sci (2013)

Transmission electron micrographs of diploid (2×) and tetraploid (4×) Robinia pseudoacacia mesophyll cells after one day and 10 days of salt treatment. (A) 0 day, 2×; (B) 0 day, 4×; (C) 10 days, 2×; (D) 10 days, 4×. CW, cell wall; Ch, chloroplast; M, mitochondrion; Nu, nucleolus; P, plastoglobule; SG, starch granule; Gr, granum; V, vacuole; Vs, small vesicle.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3821616&req=5

f7-ijms-14-20299: Transmission electron micrographs of diploid (2×) and tetraploid (4×) Robinia pseudoacacia mesophyll cells after one day and 10 days of salt treatment. (A) 0 day, 2×; (B) 0 day, 4×; (C) 10 days, 2×; (D) 10 days, 4×. CW, cell wall; Ch, chloroplast; M, mitochondrion; Nu, nucleolus; P, plastoglobule; SG, starch granule; Gr, granum; V, vacuole; Vs, small vesicle.
Mentions: The results for the physiological responses of plant growth to salt stress were different (Figures 1–8). Salt stress inhibited plant growth and decreased net photosynthetic rate and stomatal conductance in 2×. However, the decreases in these parameters were less in 4× than those in 2×. These results agree with our earlier research showing that 4× plants are relatively salt-tolerant compared to that of 2× plants [24]. Similar results were reported by another group [25]. In Figure 5, our results showed that Pn and Gs for 4× were not sensitive in response to salt stress after RWC decreases are detectable. It may be a reason that the salt stress caused less pronounced inhibition of photosynthesis in 4× than in 2×. In other words, 4× plants have higher water use efficiency under salt stress. Thus, 4× can keep photosynthesis stability under low RWC to adapt salt stress. At the same time, RWC is not only factor influencing Pn. The decrease in growth and stomatal conductance may result from reduced leaf water content. Gs plays an important role in the change in Pn. Little change in Ci was observed compared with that of Gs (Figure 3). This indicates that photosynthesis under salt stress may be affected by other factors such as the availability of ATP and Rubisco activity [26]. The changes between Pn, Gs, and Ci in 2× and 4× plants were different, which was further supported by the proteomics results. The expression levels of 19 and 16 proteins including Rubisco large subunit, rubisco activase and ATP synthase CF1 alpha subunit increased in 2× and 4× after salt treatment, respectively. MDA and REL are important indicators of the damage caused by salt stress [27]. The present results show that salinity significantly increased MDA content and REL in 2× more than those in 4×, indicating more damage to membranes in 2× plants.

Bottom Line: The results showed that diploid (2×) plants suffered from greater negative effects than those of tetraploid (4×) plants.In addition, salt stress resulted in distorted chloroplasts, swollen thylakoid membranes, accumulation of plastoglobules, and increased starch grains in 2× compared to those in 4×.Collectively, our results suggest that the plants showed significantly different responses to salt stress based on ploidy level of the plant.

View Article: PubMed Central - PubMed

Affiliation: College of Life Science, Northeast Forestry University, Harbin 150040, China. mfj19751@163.com.

ABSTRACT
Tetraploid black locust (Robinia pseudoacacia L.) is adaptable to salt stress. Here, we compared morphological, physiological, ultrastructural, and proteomic traits of leaves in tetraploid black locust and its diploid relatives under salt stress. The results showed that diploid (2×) plants suffered from greater negative effects than those of tetraploid (4×) plants. After salt treatment, plant growth was inhibited, photosynthesis was reduced, reactive oxygen species, malondialdehyde content, and relative electrolyte leakage increased, and defense-related enzyme activities decreased in 2× compared to those in 4×. In addition, salt stress resulted in distorted chloroplasts, swollen thylakoid membranes, accumulation of plastoglobules, and increased starch grains in 2× compared to those in 4×. However, 4× developed diverse responses under salt stress. A comparative proteomic analysis revealed that 41 and 37 proteins were differentially expressed in 2× and 4×, respectively. These proteins were mainly involved in photosynthesis, stress and defense, energy, metabolism, transcription/translation, and transportation. Distinct patterns of protein changes between 2× and 4× were analyzed. Collectively, our results suggest that the plants showed significantly different responses to salt stress based on ploidy level of the plant. The 4× possessed a better salt protection mechanism than that of 2×, suggesting salt tolerance in the polyploid plant.

Show MeSH
Related in: MedlinePlus