Alterations in growth and crassulacean acid metabolism (CAM) activity of in vitro cultured cactus

Guadalupe Malda, Ralph A. Backhaus, Chris Martin

Research output: Contribution to journalArticle

36 Scopus citations

Abstract

Unlike C-3 plants, cacti possess a crassulacean acid metabolism (CAM) physiology that can alter the pattern of carbon uptake and affect plant growth under artificial environmental conditions, especially in tissue culture. In vitro-derived plantlets of Coryphantha minima grew 7-fold larger than plants cultured under similar ex vitro conditions. Growth regulators incorporated into the culture media during shoot proliferation stage of micropropagation had a strong influence on this increased growth. Other important factors that contributed to increased growth under in vitro conditions were high relative humidity and sugar in the culture medium. An analysis of gas exchange and daily fluctuations of malic acid levels revealed an increase in net photosynthetic rate, in terms of carbon assimilation, by in vitro plants compared with that of ex vitro plants. This stimulated photosynthesis in the presence of an external carbon source was unexpected but apparently true for cacti exhibiting CAM physiology. Unlike CAM plants grown in ex vitro conditions, net CO2 uptake by in vitro-cultured cacti occurred continuously in the light as well as the dark. Once regenerated, cacti were transferred to ex vitro conditions where the normal CAM pathway resumed with a concomitant reduction in growth and CO2 uptake. These results showed that growth of cacti can be considerably accelerated by in vitro culture.

Original languageEnglish (US)
Pages (from-to)1-9
Number of pages9
JournalPlant Cell, Tissue and Organ Culture
Volume58
Issue number1
DOIs
StatePublished - Dec 1 1999

Keywords

  • CAM photosynthesis
  • CO
  • Coryphantha minima
  • In vitro

ASJC Scopus subject areas

  • Horticulture

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