Peach shoot types and the control of vegetative growth in trees

Do peach trees plan their shoot growth, or do they react to the environment?

In peach (Prunus persica) trees, three types of shoots can be distinguished depending on the time of their appearance: sylleptic, proleptic and epicormic. On proleptic shoots, an average of ten phytomers are preformed in dormant buds prior to shoot growth after bud-break, whereas all phytomers are considered neoformed in sylleptic and epicormic shoots.

Diagram of Proleptic and Sylleptic growth

However, casual observations indicated that proleptic and sylleptic shoots appear quite similar in number of phytomers and structure in spite of their different origins. The goal of this research was to test the hypothesis that both proleptic and sylleptic shoots exhibit similar growth characteristics by analysing their node numbers and bud fate patterns. If their growth characteristics are similar, it would indicate that the structure of both types of shoots is primarily under genetic rather than environmental control.

Prats-Llinàs et al. show that the number of phytomers and bud fate patterns of the two types of shoots are similar even though proleptic shoots started to grow earlier in the season than sylleptic shoots.

This study provides strong evidence for the semi-deterministic nature of both proleptic and sylleptic shoots across four peach cultivars in terms of number of phytomers and bud fate patterns along shoots. It is apparent that the overall structure of shoots with similar numbers of phytomers was under similar genetic control for the two shoot types. Understanding shoot structural characteristics can aid in phenotypic characterization of vegetative growth of trees and in providing a foundation for vegetative management of fruit trees in horticultural settings.

Further reading

Prats-Llinàs, M. T., López, G., Fyhrie, K., Pallas, B., Guédon, Y., Costes, E., & DeJong, T. M. (2019). Long proleptic and sylleptic shoots in peach (Prunus persica L. Batsch) trees have similar, predetermined, maximum numbers of nodes and bud fate patterns. Annals of Botany, 123(6), 993–1004. https://doi.org/10.1093/aob/mcy232