Just enough fruit: understanding feedback mechanisms during sexual reproductive development

Abstract

The fruit and seed produced by a small number of crop plants provide the majority of food eaten across the world. Given the growing global population, there is a pressing need to increase yields of these crops without using more land or more chemical inputs. Many of these crops display prominent ‘fruit-flowering feedbacks’, in which fruit produced early in sexual reproductive development can inhibit the production of further fruit by a range of mechanisms. Understanding and over-coming these feedbacks thus presents a plausible route to increasing crop yields ‘for free’. In this review, we define three key types of fruit-flowering feedback, and examine how frequent they are, and their effects on reproduction in a wide range of both wild and cultivated species. We then assess how these phenomenologically distinct phenomena might arise from conserved phytohormonal signalling events, particularly the export of auxin from growing organs. Finally, we offer some thoughts on the evolutionary basis for these self-limiting sexual reproductive patterns, and whether they are also present in the cereal crops that fundamentally underpin global diets.

Flowering Newsletter 2023

“…From an agricultural perspective, maximizing fruit number—and thus yield—is desirable. However, as Sadka et al (2023) explain, plants have evolved several feedback loops that finely regulate how much fruit is produced. While those feedback mechanisms might be an important evolutionary strategy to ensure reproductive success in unpredictable environments, breaking fruit-limiting feedback loops might be a promising avenue for plant breeding to increase yield ( Sadka et al , 2023 ).…”

“…While Sadka et al (2023) provide insights into feedback mechanisms regulating fruit set, Balanzà et al (2023) approach the topic of how the end of flowering is regulated from a molecular genetic perspective. They outline the numerous genes and pathways involved in this process in Arabidopsis.…”

“…The articles by Balanzà et al (2023) and Sadka et al (2023) show that we are only beginning to understand the molecular mechanisms governing the end of flowering. In contrast, the beginning of flowering has been among the first traits dissected genetically in plants.…”

“…This may relate to testing new allelic combinations, as suggested for flowering time in cereals ( Slafer et al , 2023 ), but may also involve exploiting the plethora of effects of phytohormones. Indeed, phytohormones are involved in virtually all developmental processes, and carpel, seed, and fruit development or senescence are no exception here ( Balanzà et al , 2023 ; Parveen et al , 2023 ; Reyes-Olalde et al , 2023 ; Sadka et al , 2023 ). Phytohormones or derivatives thereof are already used in agriculture to control, for example, plant height, and we may we be able to use similar compounds in a targeted manner in the future to further increase crop performance.…”