Plastid division and morphology in the genus Peperomia

Abstract

We have investigated several factors determining plastid size and number in Peperomia, a genus in the Piperaceae family whose species naturally display great interspecific variation in chloroplast size and number per cell. Using microscopic techniques, we show that chloroplast size and number are differently regulated in the palisade parenchyma and the spongy parenchyma, suggesting that chloroplast division in these cell types is controlled in different ways. Microscopic studies of iodine-stained root cells revealed a correlation between amyloplast size in root cells and chloroplast size in palisade parenchyma cells. However, despite substantial variation in chloroplast number in leaf mesophyll cells, amyloplast number in root cells was very similar in all species. The results suggest that organelle size and number are regulated in a tissue-specific manner rather than in dependency on the plastid type. We also demonstrate that plastid size determines the size but not the number of starch grains in root amyloplasts.Additional key words: amyloplast, chloroplast, plastid number, plastid size.

Allelic Variation in the Chloroplast Division Gene FtsZ2-2 Leads to Natural Variation in Chloroplast Size

“…Natural variation in chloroplast size or other aspects of chloroplast morphology has rarely been systematically investigated within a single species (Jellings et al, 1983). However, such differences have been reported between species (Honda et al, 1971;Jellings and Leech, 1984;Pyke and Leech, 1987), in different cell and tissue types within a species (Dengler et al, 1996;Pyke, 1997;Ahmadabadi and Bock, 2012;Stata et al, 2014;Swid et al, 2018), and under different environmental conditions (Boardman, 1977;Tsuji et al, 1979;Possingham et al, 1988;Filek et al, 2010;Li et al, 2013b;Takemura et al, 2017). Chloroplast size differences have been particularly well documented in response to light conditions.…”

Decoding Natural Variation in Chloroplast Size

“…Defects in chloroplast division have been linked to abnormal chloroplast movement, effects on photosynthesis, and reduced mesophyll conductance (Austin and Webber, 2005;Dutta et al, 2017). In nature, chloroplast number or size can vary between species (Honda et al, 1971) and also between cell types of the same species (Ahmadabadi and Bock, 2012); however, the genes/alleles responsible for this variation are unknown. In this issue of Plant Physiology, Kadirjan-Kalbach et al (2019) explored the molecular mechanisms underlying natural variation in chloroplast size using different accessions of Arabidopsis (Arabidopsis thaliana).…”

“…Given our extensive use of Arabidopsis as a model plant, especially for cell and molecular biology, similar approaches will undoubtedly be useful in understanding more aspects of plant cell biology. This approach may also help inform our understanding of how chloroplast size is determined in species other than Arabidopsis, including those that show cell typespecific variation in chloroplast size (Ahmadabadi and Bock, 2012…”