Abstract
Chloroplasts are indispensable for higher plants. The growth and development of plants are very sensitive to environmental temperature changes, and chloroplast development is also regulated by adverse environmental temperatures. However, the molecular mechanism of how plants coordinate chloroplast development and environmental temperature changes remains largely unknown. Here, a temperature-conditioned chloroplast development defective mutant thermo-sensitive mutant in leaf color 2 (tsl2) of Arabidopsis was obtained through a forward genetic screening. The tsl2 mutant showed a weak yellowish phenotype at normal growth temperature (22°C), and the phenotype was more pronounced at low growth temperature (16°C) and largely rescued at high growth temperature (29°C). Bulk Segregant Analysis (BSA) revealed that TSL2 encodes FtsH-Inactive Protein 5 (FtsHi5). Genetic complementation analysis confirmed that complemented expression of FtsHi5 rescued the chlorophyll content and thylakoid development defects observed in tsl2 mutants at 16°C. Quantitative mass spectrometry analysis with Tandem Mass Tag (TMT) isobaric labeling revealed broad changes in the chloroplast proteome of tsl2 mutant plants at low temperature, which is agreed with the impaired chloroplast biogenesis and function in tsl2 plants. Together, our data demonstrates that FtsHi5/TSL2 plays an important role in chloroplast development and protein accumulation in chloroplasts, especially at low environmental temperatures in Arabidopsis.
Highlights
Chloroplast biogenesis affects plant growth and development due to its functions in photosynthesis and biosynthesis of amino acids, fatty acids, nucleotides, and phytohormones (Neuhaus and Emes, 2000)
The phenotype was more pronounced when the growth temperature was reduced to 16◦C, and the leaf color of tsl2 was similar to that of the wild type (WT) when the temperature was increased to 29◦C (Figure 1A)
To further characterize the tsl2 mutant, we examined the chlorophyll contents in tsl2 and WT seedlings grown at different temperature conditions
Summary
Chloroplast biogenesis affects plant growth and development due to its functions in photosynthesis and biosynthesis of amino acids, fatty acids, nucleotides, and phytohormones (Neuhaus and Emes, 2000). The plastid retains a functional genome which encodes about 100 proteins, while most of the other ∼2,000–3,000 proteins within chloroplasts are imported from the cytosol via the translocon at the outer envelope membrane of chloroplasts (TOC) and. FtsHi5 Regulates Chloroplast Development translocon at the inner envelope membrane of chloroplasts (TIC) systems (Li and Chiu, 2010; Jarvis and Lopez-Juez, 2013). Protein homeostasis (proteostasis) in chloroplasts, maintained by a balance between protein import form cytosol, synthesis and degradation within chloroplasts, is essential for its functions during plant growth, development, and stress resistance (Sun et al, 2021)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
