Plant biology

Chloroplast to Nucleus Feedback by SXD1

Science's STKE  15 May 2001:
Vol. 2001, Issue 82, pp. tw3
DOI: 10.1126/stke.2001.82.tw3

Provencher et al. have identified a gene, sxd1, that encodes a protein that functions in a negative feedback pathway from the chloroplast to the nucleus. In normal plants, SXD1 protein is found in chloroplasts; in its absence, SXD1-deficient plants produced and accumulated greater than normal quantities of sucrose, fructose, and glucose. Increased starch storage in SXD1-deficient plants led to severe distension of the chloroplasts. However, SXD1-deficient plants were not defective in exporting fixed carbon molecules from their chloroplasts. Rather, SXD1-deficient plants were unable to decrease the expression of genes essential for photosynthesis. Thus, the authors hypothesize that SXD1 may be important for sugar sensing and control of photosynthesis by chloroplast-to-nucleus feedback.

L. M. Provencher, L. Miao, N. Sinha, W. J. Lucas, Sucrose export defective1 encodes a novel protein implicated in chloroplast-to-nucleus signaling. Plant Cell 13, 1127-1141 (2001). [Abstract] [Full Text]