A roadmap of the genes which drive plant architecture in maize will help, because plants grow throughout their entire life, controlled by a small structure at the tip of the plant’s shoots, known as the meristem.
The meristem is the control center for the maintenance of stem cells – which can be converted into any cell type – and for the creation of plant organs such as side shoots and leaves. The meristem is different in shape and size in differing species such as maize and thale cress and a new paper has discovered that the meristem has even greater tasks than scientists had realized. It controls the architecture of the whole plant from the very tip. By mapping the genetic circuits involved in these functions in maize, the team has discovered key starting points for technological improvement of crops.
In multicellular organisms, cells have to communicate with each other in order to coordinate development. They recognize their position within the organism by creating and perceiving signal molecules; this enables them to decide which cell types are to be formed at which location.
The meristem at the tip of the shoot considers all kinds of developmental and environmental signals. Previously, it was assumed that the meristem only decided whether new stem cells or organs were to be formed. Working with her team, Timmermans has now precisely described the molecular circuits that are active in the cells of the meristem, drawing a roadmap of those circuits and describing each one’s functions. The team identified mechanisms that specifically control the stem cells in maize, and have found that these also affect the overall architecture of the plant.
Marja Timmermans in a test corn field. Photo: Gunther Willinger
These latest findings can be used for plant breeding and cultivation. “Maize yields have increased steadily over the last century. However, there was no significant increase in the number of grains produced per plant,” says Professor Marja Timmermans from the University of Tübingen . “Rather, maize hybrids have been bred to thrive in denser plantations. The architecture of the maize plants, the angle and shape of the leaf play a vital role in the plant’s ability to efficiently catch the light and carry out high-performance photosynthesis. The genetic circuits identified can now be used for further optimization.”
Citation: Steffen Knauer, Marie Javelle, Lin Li, Xianran Li, Xiaoli Ma, Kokulapalan Wimalanathan, Sunita Ku-mari, Robyn Johnston, Samuel Leiboff, Robert Meeley, Patrick S. Schnable, Doreen Ware, Carolyn Lawrence-Dill, Jianming Yu, Gary J. Muehlbauer, Michael J. Scanlon, and Marja C.P. Timmermans: A high-resolution gene expression atlas links dedicated meristem genes to key architectural traits. Genome Research, 29, 1962. DOI:10.1101/gr.250878.119
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