Respiration during slow desiccation of the poikilochlorophyllous desiccation tolerant plant Xerophyta scabrida at present-day CO2 concentration

Z. Tuba, N. Smirnoff, Z. Csintalan, K. Szente, Z. Nagy

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

The time-course of changes in photosynthesis and respiration during long-term desiccation of the poikilohydric desiccation tolerant (PDT) monocot Xerophyta scabrida are reported. Complete leaf desiccation required 16 days. A large reduction occurred in the leaf area/leaf weight ratio that resulted in an extended period of desiccation by reducing the rate of water loss. Net CO2 assimilation declined sharply in the desiccating leaves and ceased altogether after day 3. The reduction in net CO2 assimilation was associated with a decrease in chlorophyll a+b content, a reduction in photochemistry and stomatal closure. The chlorophyll/carotenoid ratio [(a+b)/(x+c)] reflected that the disorganization of the photosynthetic pigment composition and the photosynthetic system began after net CO2 assimilation stopped. The leaves lost 86% of their chlorophyll a+b content and 70% of their carotenoids after 16 days. The reduction in the variable chlorophyll fluorescence decrease ratio Rfd690 values during desiccation indicated a decrease in the activity of the chlorophylls and the thylakoids and the eventual cessation of photochemical activity. In contrast to photosynthesis, respiration was much less affected during the desiccation period and was detectable until near the end of the desiccation period. The respiration rate was linearly related to tissue water content on a fresh weight basis. X. scabrida is able to maintain respiration for a longer period than homoiochloropyllous desiccation tolerant (HDT) plants which maintain their pigment content and chloroplast integrity during desiccation. This response in X. scabrida is suggested to maintain energy supply allowing controlled breakdown of photosynthetic pigments and disorganization of the chloroplasts into desiccoplasts. The respiration which occurs during desiccation is termed desiccation respiration.

Original languageEnglish
Pages (from-to)381-386
Number of pages6
JournalPlant Physiology and Biochemistry
Volume35
Issue number5
Publication statusPublished - Jan 1 1997

Keywords

  • Respiration
  • Xerophyta scabrida
  • desiccation tolerance
  • poikilochlorophyllous
  • water stress

ASJC Scopus subject areas

  • Physiology
  • Genetics
  • Plant Science

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