PLANT CELL CULTURE- THE NEXT DIRECTION?

(PICTURE TAKEN FROM WWW.BOTANY.UNIMELBOURNE.EDU.AU)

(PICTURE TAKEN FROM WWW.JMU.EDU)
There are various limitations which we faced in practicing conventional agriculture for our plant food sources. Other problems include environmental factors such as drought, floods, diseases, political and labour instabilities in the producing countries. There are then also the problems of uncontrollable variations in the crop quality, inability of authorities to prevent crop adulteration, losses in storage and handling

In view of these problems there are attempts to find better ways of plant production or producing valuable metabolites from the plants using more modern technology. It is only natural and logical to try to apply what technology that have been acquired in fermentation technology to be applied in the cultivation of plant or plant cells for their products. The similarity of microbial cells and single plant cells makes it a natural prigression in the attempts to cultivate the plant cells in fermentors. This is especially so after the success of plant tissue culture in generating calluses and plantlets from explants

While it is inconceivable to grow large plants in fermentors,the situation is very practicable for the culture of plant cells itself. In trying to grow plant cells in fermentors there are problems faced especially with regard to different physical and physiological characteristics between plant cells and microbial cells

CHARACTERISTICS



----------------------MICROBIAL CELL------------------------PLANT CELL
Size --------------------2 u-------------------------------- >10 u
Shear stress ----------Insensitive----------------------------Sensitive
Water content ------------75% ------------------------------>90%
Duplication time--------<1 hour ------------------------------------days
Aeration ---------------1-2 vvm -----------------------------------0.3 vvm
Fermentation time --------Days -----------------------------------Weeks
Product accumulation ----Medium --------------------------------Vacuole
Production phase -------Uncoupled --------------------------Often growth-linked
Mutation ----------------Possible-----------------------------Requires haploids
Medium cost ($)
(MS medium)----------------8-9/m -------------------------------65-70/m

Source: Zenk, M.H., Plant Cell Culture Conference, Oyez Sci, Tech. Serv. (1982)

From the aspects of fermentation technology, the key problem areas are:
1 Plant cells are too fragile compared to microbial cells
2 Plant cells takes too long to grow in fermentors compared to microbial cells
3 Oxygen consumption is lower compared to microbial cells

As for product formation it will be a downstream problems of fermentation technology

The consequences of the three main points above are:
Since plant cells are shear sensitive supplying air or mixing will be a problems as those processes are intense shear generating forces
Too long a growth time in the fermentor will lead to the potential problem of microbial contamination to occur and fermentation disaster
Oxygen supply will have to be provided by a more suitable and controlled system

Note: In our discussion here we are more towards the cultivation of plant cells that originate from multicellular plants and not from single cell plants such as the unicellular or filamentous algae



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