Assembly and use of a plant gnotobiotic growth system for plant–microbe interaction studies in cereals

The development of microbial-based agricultural amendments that work
consistently in the field requires an understanding of the molecular
mechanisms of plant–microbe interactions. Studying these underlying
mechanisms of interaction demands the ability to grow plants under
environmentally controlled and gnotobiotic conditions (i.e. all
microorganisms interacting with the plant are known, whether that is
germ-free, defined microbial communities, or natural communities). The
currently available plant gnotobiotic systems are not suitable to study
large plants of agricultural relevance such as cereals. Moreover, most of
these systems lack the ability to manage irrigation.  Here we
introduce GNOVA, a new gnotobiotic system designed to accommodate cereal
plants with the ability to manage irrigation. This  new system is
an accessible platform composed of a 3D printed base and commercially
available materials. This protocol provides a step-by-step guide to
assembling the system and experiment set up. Furthermore, we present a
performance comparison of GNOVA to a gnotobiotic bag system. GNOVA
extended plant growth from two weeks in the bag system up to 17 weeks for
wheat and 4 weeks for maize. The germination rate of both crops also
increased within GNOVA from 66% to 100% for wheat and from 75% to 100% for
maize. Wheat grown within GNOVA developed tillers, which were absent in
plants of the same age within the bag system. The fresh weight of maize
grown in the GNOVA was 594% higher than in the bag system. Additionally,
the shoot height and root length of maize were 89% and 57% greater within
the GNOVA system than in the bags, respectively. The GNOVA system extends
the toolbox available to scientists for the exploration of
plant–microbiota interactions beyond the seedling stage in cereals by
providing increased growth space and irrigation management.