The Arabidopsis QQS Orphan Gene Modulates Carbon and Nitrogen Allocation Across Species

The Arabidopsis thaliana QQS-orphan-gene modulates carbon and nitrogen allocation to protein and starch¹. Ectopic expression of QQS increases protein content² in leaf and seed in soybean Williams82³, in soybeans with different high-/low-protein levels, and in rice and corn⁴. QQS transcript levels are altered in plants under stresses and in mutants of genes involved in all sorts of stress responses, indicating that QQS may integrate primary metabolism and environmental perturbations, thus adjusting the plant’s adaption to abiotic and biotic stresses⁵. The QQS protein binds to a transcriptional regulator in Arabidopsis and its soybean, rice and corn homologs: Nuclear Factor Y subunit C4 (NF-YC4). Overexpression of NF-YC4 in Arabidopsis, soybean and rice mimics QQS-overexpression phenotype, increasing protein content and decreasing carbohydrate⁴. Mutants overexpressing genes related to QQS network have significantly reduced susceptibility to plant pathogens and pests⁶. Little is known about the functional significance of the species-specific orphan genes^{1, 4, 7}. Our data reveal the core of a previously undefined network in which QQS participates and indicate QQS exerts its effect via an interaction with a transcription factor conserved across eukaryotic species⁴; these findings open a new non-transgenic strategy to create high-protein crops and enhance crop disease resistance⁶. Crop plants must integrate signals from the environment and prioritize responses to stresses that may occur individually or simultaneously throughout the growing season. Stress responses can adversely affect plant growth and quality traits such as protein and starch. Deficiency in dietary protein is globally one of the most severe health problems; the ability to optimize protein productivity of plant-based foods has far-ranging impact on world health and sustainability. Our research presents QQS as a model plant orphan gene regulating plant metabolism and adaptation to environment, and illustrates an example of basic research in Arabidopsis applied in agriculture.

References

¹Li et al. PJ (2009).

²Li et al. U.S. Patent 9157091 (2012).

³Li et al. PBJ (2015).

⁴Li et al. PNAS (2015).

⁵Arendsee et al. TIPS (2014).

⁶Li et al. U.S. Patent Office 62/244,131 (2015).

⁷Jones et al. Frontiers Plant Science (2016)