Changes in the levels of chlorophyll and light-harvesting chlorophyll a/b protein of PS II in rice leaves aged under different irradiances from full expansion through senescence

Jun Hidema, Amane Makino, Yasuko Kurita, Tadahiko Mae, Kunihiko Ojima

Research output: Contribution to journalArticle

58 Citations (Scopus)

Abstract

Effects of irradiance on changes in the amounts of chlorophyll (Chl) and light-harvesting chlorophyll a/b protein of PS II (LHCII) were examined in senescing leaves of rice (Oryza sativa L.). Results of treatments at two irradiances (100% and 20% natural sunlight) were examined after the full expansion of the 13th leaf throughout the course of senescence. With 20% sunlight, the Chl content decreased only a little during leaf senescence, while with 100% sunlight it decreased appreciably. Similarly, the amount of LHCII protein during treatment with 20% sunlight remained almost constant. However, the ratio of Chl a/b during the shade treatment decreased significantly and the rate of decrease was greater than during the full-sunlight treatment. The ratio of Chl a/b for Chl a and b bound to LHCII was about 1.2, irrespective of leaf age or irradiance treatment. When the amounts of Chl bound to LHCII were calculated from the total leaf content of Chl and the ratio of Chl a/b, assuming a ratio of Chl a/b bound to LHCII of 1.2, they were well correlated with the amounts of LHCII protein.Changes in the amounts of LHCII synthesized during the two irradiance treatments were examined using an 15 tracer. Incorporation of 15N into LHCII declined dramatically during both treatments from full expansion through senescence, suggesting that there was little synthesis of LHCII protein during that time. In addition, the amount of LHCII synthesized during senescence was lower during the shade treatment than during the 100% sunlight treatment. These results indicate that the absence of an apparent change in levels of LHCII with shade treatment during senescence was caused by the very low rate of turnover of LHCII protein.

Original languageEnglish
Pages (from-to)1209-1214
Number of pages6
JournalPlant and Cell Physiology
Volume33
Issue number8
Publication statusPublished - 1992 Dec 1

Keywords

  • 15 tracer
  • Chlorophyll
  • Irradiance
  • Light-harvesting chlorophyll complex II (LHCII)
  • Rice leaf
  • Senescence

ASJC Scopus subject areas

  • Physiology
  • Plant Science
  • Cell Biology

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