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Kiss Máté

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Kiss Máté
Tissue hierarchies in plants can efficiently minimize somatic evolution and act as a functional germline

Aug 29 - csütörtök

09:05 – 09:20

Elméleti biofizika

E36

Tissue hierarchies in plants can efficiently minimize somatic evolution and act as a functional germline

Kiss Máté¹, Derényi Imre¹ és Szöllősi Gergely János¹

¹ Eötvös Loránd Tudományegyetem Biológiai Fizikia Tanszék,

ELTE-MTA „Lendület” Evolúciós Genomika Kutatócsoport

Plant growth is governed by cell divisions in the apical meristems, which are tissues of undifferentiated cells in the shoot buds. The central zone of each meristem harbors a small group of slowly dividing stem cells. From time to time meristems also produce cells that give rise to leaves and a new meristem, called axillary meristem, in the axil of each leaf. These axillary meristems have the potential to turn into apical meristems and start to form new branches, but it is not a priori known which ones.

Recent studies have found surprisingly few genetic differences between distant branches of large plants which implies that plants can manage to keep the number of cell divisions along each lineage low (less than one per year), despite the large number of constantly produced stem cells of the axillary meristems and the inherently stochastic nature of the growth process.

To understand how plants can minimize somatic evolution, we developed a hierarchical meristematic tissue model and used computer simulations to find the optimal parameters that minimize the number of cell divisions along each lineage. We found that the optimal solution involves slow stem cell divisions in the apical meristems, and an exponentially increasing divisional rate of cells away from the central zone. New axillary meristems are produced from a few cells at the edges of apical meristems via cell divisions along a perfect binary tree.

While recent empirical evidence suggests a non-segregated functional germline in plants, it has been unclear how plants are able to produce the steady source of cells with low divisional numbers that are necessary to limit intergenerational mutation rates. Our results demonstrate that there exists an efficient mechanism, which renders germline segregation unnecessary, as the tissue hierarchies underlying plant growth are themselves able to minimize the accumulation of somatic mutations to sufficient extent.