Characterisation of Simple In Vitro Cultures of Striga hermonthica Suitable for Metabolic Studies

Abstract

The aim of this study is to develop simplified models for standardised screenings of xenobiotics, especially targeted against mannitol production, to control the harmful parasite, S. hermonthica. Chlorophyllous protoplasts and calli were produced from the young leaves of the parasite. Best yield from protoplast isolation was obtained when leaf segments were incubated at 30 °C, in the light, under shaking in an enzyme cocktail containing 2 % cellulase Onozuka R10, 0.1 % Pectolyase and sorbitol 1 M as the osmoticum. Oxygen exchange measurements, as well as labelling experiments with 14C‐bicarbonate, emphasised a significant decrease in photosynthetic capacity of protoplasts, mannitol remaining, however, a major primary product of photosynthesis. Initiation of cell cultures was unsuccessful and instability of protoplasts prevents their standardised utilisation for herbicide screening. In contrast, globular calli produced first on MS medium containing 0.5 mg L‐1 NAA, 2.5 mg L‐1 BAP and 2 % sucrose were stable for two years, after monthly subculturing on fresh medium. Sucrose substitution by mannose in the medium did not change kinetic growth and stability. Potential autotrophy was lost for calli by increasing exogenous sugar level. Biochemical analyses and labelling experiments with 14C‐bicarbonate or 14C‐sucrose or ‐mannose showed that carbon partitioning is modified in calli, in comparison with young leaves or protoplasts, sucrose or mannose accumulation being favoured in sucrose‐ or mannose‐fed calli, respectively. However, carbon flow towards mannitol was more marked in calli growing on high mannose medium. Stability and preservation of an active mannitol biosynthetic pathway allows planning of xenobiotic assays with calli as a simplified model for Striga hermonthica.

Stable transformation and actin visualization in callus cultures of dodder (Cuscuta europaea)

“…The current literature provides a little information about in vitro cultivation of parasitic plants (Srivastava & Dwivedi 2001;Rousset et al 2003). Deeks et al (1999) summarized from previously published data responses of 23 genera of parasitic plants to tissue culture conditions.…”

Targeted distribution of photo-assimilate in Striga hermonthica (Del.) Benth parasitic on Sorghum bicolor L.

“…Striga hermonthica culture on Sorghum bicolor was grown as described previously (Pageau et al, 1998;Rousset et al, Cellulose d 13 C (%) b S1 À13.2 À20.8 À23.0 À22.9 À25.0 À27.1 À29.5 S2 À13.0 À20.7 À22.9 À23.1 À26.0 À27.1 À29.0 Dd 13 C (%) c Mean (S1;S2) 0 Chlorophyll a + b in total dry matter (%) S2 --3.1 2.7 2.9 7.5 4.7…”

In Vitro Host-Free Seed Culture, Callus Development and Organogenesis of an Obligatory Root-Parasite Striga hermonthica (Del.) Benth: The Witch-Weed and Medicinal Plant

“…14,25,27 Nevertheless, the above growth requirements were used in the callogenesis study of S. hermonthica. 17 In this study, due to the debates about the growth requirements regarding the in vitro culture development of S. hermonthica, we based on the general MS medium constituents for plant in vitro culture. 17,19 Influence of auxins growth regulators and sucrose concentration on callus induction…”

“…14 Nevertheless, growing these parasitic plants in vitro is difficult, because of their dependence on connection to hosts for normal development and because of their specific germination requirements. [14][15][16] There has been only one report of S. hermonthica calli using the fresh leaves as explants, 17 here, for the first time we successfully induced the S. hermonthica callus induction and shoot regeneration directly or from the produced calli using in vitro stem segments as explants for both callogenesis and shooting. The current study was undertaken with a primary objective of establishing and defining an effective in vitro system for callus induction using MS media treated with sever-al natural and synthetic auxins each alone or in combinations with BAP.…”

“…While metabolic profiling in plants is increasing, such studies have not been carried out yet on a parasitic plant, and information on the biochemistry of S. hermonthica remains poor. 17 Our current established callus induction system is suitable for the comparative metabolomics studies toward understanding the infection mechanisms by inducing an in vitro infection and for the folkloric medicinal applications as well.…”