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Obtaining and maintaining healthy Arabidopsis plants.

yuval eshed
Yuval Eshed, Dept. of plant sciences. Weizmann Institute, Greenhouses unit, PI.yuval eshed

In the research environment of our department, it was practically impossible to fulfill the needs of all groups for growth space, flexible conditions and proper phytosanitary maintenance. The different research groups had different, and changing, requirements for growth regimes. Young and old plants were kept together, and worse of all, there was a constant demand for larger growing space, especially, with the rapid introduction of Arabidopsis as a genetic model system, with its numerous and diverse resources. It was these problems that initiated the interaction between our department and Yuval Inc. which led to the gradual development of GrowMod, which as described below, provided several simple and very efficient solutions to many of our growth problems.

Preventive and active sanitation

Under the growing conditions we have, a closed ands air-conditioned growth unit, we experience several types of pests; powdery mildew, aphids, mites, and worse of all, the fungus gnats' larva. The first three infect mostly older and weaker plants, and therefore, good growth conditions, which include regular irrigation and fertilization, are key for the plant success to battle with minor infestation. More serious one require of course chemical treatment, a procedure we try to reduce to minimum because of the plant’s susceptibility to many pesticides and even more, their surfactants.
The problem with fungus gnats emerged from the beginning as most severe problem for growing the miniature Arabidopsis seedlings. Eggs of these small flies are part of practically every soil source we could get, turning the infestation into a chronic problem. The hatching larva of these flies live of the alga and moss that develop on the wet soil surface. The combination of convenient temperatures, water, light and fertilizers make the growth media ideal for the alga and moss, which in turn make it ideal to the fungus gnats. The unique irrigation system of GrowMode, whereby by soils is periodically irrigated from underneath, and unused water are subsequently drained, nearly solved the fungus gnats infestation, as soil surface is nearly always dry. The dry surface does not allow the young larvae food to develop, and thus, inhibits their growth. As only large and mature larvae are capable of chewing Arabidopsis seedlings, damage is reduced to nearly none.
Lastly, as all trays in a shelf are irrigated together, systemic pesticide applications to all at once is now easy, fast and uniform.

Flexible design unit

To accommodate for the changing needs of the department, GrowMod units were purchased and installed on the basis of demand and space availability. As each unit is made of three shelves, it makes a very efficient use of the limited space available for us. For our own needs, we equipped several rooms in the basement of our building with central air conditioning units, and over time, filled the rooms with the modular units. And while each unit can be programmed for a different day length, we chose to program individual rooms, and share the communal space.
Although we did not try it, individual units can probably be placed within a more spacious lab, to provide an easily accessible plant material.

Simple operation

The growth and maintenance of plants require daily examination, cross collection and when necessary, irrigation. In the past, an irrigation cycle would require lengthy period of individual tray filling, and unfortunately, occasional plant loss due to irreversible drought stress. The introduction of a “one button operation cycle” which leads to irrigation till the predetermined water level, timed watering period (20 minutes in our case) and subsequent water drainage, turned the irrigation into an effortless task. Moreover, this task requires now minimal training or previous experience. There is no concern of over or under-watering and the whole process is completed in minutes.
While it is feasible to fully program the control unit, we prefer to operate it manually, as it is so simple, and as this way, a regular visit of the plants is maintained.
In summary, there are many ways to grow plants, Arabidopsis included. However, for our needs, introduction of the GrowMod units helped to make better use of the limited space we have, made it more costly efficient, allowed us to fulfill the requirements for P1 bio-safety rules and made the task of obtaining healthy and reproducible plants far easier.