Barking up the wrong tree (An opinion)

 

Danforth Center (USA) received from NSF $3.4 million in 2017/18 to improve maize architecture by the study of the molecular networks and interactions controlling architecture (leaf angle, panicle morphology etc’) and thus understand how to modify maize architecture toward improving yield potential.

We already know that the current crop plant morphology and phenology has been basically (empirically) optimized for each specific environment. It was optimized in terms of maximizing the interception of solar photosynthetic active radiation per unit crop land. It is reasonably and practically impossible to increase yield by just yield components morphology manipulation (albeit understanding their molecular basis) without increasing the available carbon to the grain. Yield can be increased mainly by mobilization of a larger part of total plant assimilates to grain (‘harvest index’) or by increasing total assimilates per plant (larger biomass). Since ‘harvest index’ has been basically optimized, the correct direction of research is currently demonstrated by the attempts to increase assimilation. We have evidence that yield improvement beyond the 1960’s “green revolution” achievement is correlated with a genetic increase in leaf stomatal and mesophyll conductance which allows for greater CO2 uptake and assimilation. Serious avenues of approach are now being taken via several physiological and metabolic processes which we know lend themselves to molecular manipulations. For example, by RUBISCO enhancement or its thermal stabilization (e.g.). The research on the molecular networks controlling plant architecture will most likely come back at the end to this well-known conclusion as held today by practicing breeders and crop physiologists. The understanding of how various plant architectural components interact on the molecular level is fine, but in terms of attaining a potential yield increase it is really “barking up the wrong tree”.