The role of branch architecture in assimilate production and partitioning: the example of apple (Malus domestica)

Abstract

Understanding the role of branch architecture in carbon production and allocation is essential to gain more insight into the complex process of assimilate partitioning in fruit trees. This mini review reports on the current knowledge of the role of branch architecture in carbohydrate production and partitioning in apple. The first-order carrier branch of apple illustrates the complexity of branch structure emerging from bud activity events and encountered in many fruit trees. Branch architecture influences carbon production by determining leaf exposure to light and by affecting leaf internal characteristics related to leaf photosynthetic capacity. The dynamics of assimilate partitioning between branch organs depends on the stage of development of sources and sinks. The sink strength of various branch organs and their relative positioning on the branch also affect partitioning. Vascular connections between branch organs determine major pathways for branch assimilate transport. We propose directions for employing a modeling approach to further elucidate the role of branch architecture on assimilate partitioning.

Multiple pathways regulate shoot branching

“…Finally, several more or less detailed models are available in the literature to model the temporal dynamics of nitrogen and carbon compounds ( Tabourel-Tayot and Gastal, 1998 ; Allen et al, 2005 ; Luquet et al, 2006 ; Kang et al, 2008 ; Fanwoua et al, 2014 ). In all these models, nitrogen and carbon dynamics are modeled from the difference between assimilation (photosynthetic organs for C, roots for N) and consumption by growing organs.…”

Expression of MdCCD7 in the scion determines the extent of sylleptic branching and the primary shoot growth rate of apple trees

“…In perennial species, branching is even more complex because axillary meristems can have multiple fates: extending into a shoot without a dormant period (sylleptic shoot), developing into a vegetative shoot after a dormant period (proleptic shoot), developing into a floral bud that opens the following spring, or remaining dormant indefinitely ( Costes et al , 2014 ). In addition, environmental signals such as temperature and day length, planting density, internal competition for carbon between buds, and the effects of pruning and plant manipulation all integrate to regulate the outgrowth of axillary meristems and buds ( Girault et al , 2008 , 2010 ; Henry et al , 2011 ; Rabot et al , 2012 ; Djennane et al , 2014 ; Fanwoua et al , 2014 ).…”

Yield and Fruit Quality of Almond, Peach and Plum Under Regulated Deficit Irrigation

“…Indeed, fruit size and biochemical composition depend in part on carbon and nitrogen assimilation and partly on fruit growth (genetically determined) but are modulated by the environment [18] . A pre-flowering water deficit reduces the number of fruits but fruit size can remain stable or may even increase due to an enhancement of availability of assimilates to each fruit [19] . In this case, water deficit effects on fruit quality are limited.…”