PLT · PLETHORA transcriptions factors, new players in the control of phyllotaxis in Arabidopsis thaliana
7РП — „Хора“ (Действия „Мария Кюри“)
- Период
- 2010-03-01 → 2012-02-29
- Финансиране от ЕС
- 160 749 €
- Участници
- 1
- Схема
- MC-IEF
Линиите свързват координатора с партньорите.
Накратко на български
Генните фактори PLT контролират разположението на листата при растението Arabidopsis thaliana, като определят дали те ще растат в спирала или един срещу друг. Това помага да се разбере как хормонът ауксин регулира архитектурата и развитието на растенията.
Кратко обяснение, генерирано от езиков модел по текста на CORDIS. Оригиналът е по-долу.
Резултати накратко
PLETHORA transcriptions factors, new players in the control of phyllotaxis in Arabidopsis thaliana
In plants, the shoot apical meristem (SAM), located at the tip of the stem, is the source of all above ground post embryonic organs. The SAM arises during embryogenesis and operates throughout the life of the plant to maintain a self-renewed population of undifferentiated stem cells and to generate different types of organs. Lateral organs, such as leaves and flowers, follow a regular pattern, or phyllotaxis, that can be described mathematically and defines part of the plant architecture. One of the most abundant lateral organ pattern in nature is the spiral phyllotaxis, found in the plant model Arabidopsis thaliana. This pattern is described by successive organs along the stem being separated by the so called 'golden angle' 137.5°. Recently we reported that in Arabidopsis, the triple loss-of-function mutant plethora3, plethora5, plethora7 (plt3plt5plt7) is defective in establishing spiral phyllotaxis and preferentially adopts a distichous pattern of lateral organ initiation where organs form sequentially separated by 180°. PLT3, PLT5 and PLT7 genes encode for AP2 domain transcription factors. Phyllotaxis is known to be dependent on the phytohormone auxin polarised transport; however, what parameters control precise switch in phyllotaxis are unknown. Using a domain specific complementation approach, I demonstrated that PLT's function in the centre of the meristem is required and sufficient for organ patterning. During this project, I showed that auxin biosynthesis is reduced in the apex of plt3plt5plt7, and mutants with reduced auxin biosynthesis leads to a similar phenotype as plt3plt5plt7. Moreover, expression of the auxin biosynthetic gene YUCCA4 in the centre of plt3plt5plt7 meristem fully complements the triple mutant phyllotactic phenotype. Therefore, PLT transcription factors regulate auxin biosynthesis throughout the meristem, controlling the quantity of auxin available for organ initiation and patterning. The observation of central zone markers showed that the stem cell niche sise is reduced in plt3plt5plt7 mutant background. Increasing the sise of the stem cell niche by increasing the phytohormone cytokinin biosynthesis in plt3plt5plt7 background is also sufficient to rescue the organ patterning defect of the mutant. Expression analysis of marker genes showed that the rescue of plt3plt5plt7 observed with cytokinin biosynthesis is not correlated to a larger stem cell niche, but to a higher auxin production. Together these data show that PLT-mediated control of auxin biosynthesis in the SAM regulates phyllotaxis. Furthermore, this work emphasises the tight cross regulation between cytokinin and auxin biosynthesis to couple stem cell fate to organogenesis and phyllotaxis.
Текст от CORDIS, на английски · Данни: CORDIS, © Европейски съюз
Цел на проекта
The mathematical regularity of plant organ initiation, also known as phyllotaxis, has always intrigued mathematicians and botanists. Only recently was established that the plant hormone auxin has a major role in regulating organ positioning at the shoot apex of plants. Specific spatial accumulation of auxin induces organ formation and control organ spacing. The current model for phyllotaxis relies on polar auxin transport via auxin efflux facilitators of the PIN family, and postulated positive feedback loops between auxin and PIN proteins. However no regulatory mechanism and gene network have been proposed yet to explain how organ positioning is controlled in plants. The proposal aims to bridge this gap by using a unique genetic tool generated in the host laboratory, a mutant in the plant model Arabidopsis that switches from wild type spiral organ arrangement (organs arising by a divergent angle of 137.5º) to a decussate pattern (organs arising in opposite pairs). The mutant is impaired in three genes that belong to the PLETHORA (PLT) family genes previously described in roots as involved in a regulatory loop with auxin and PIN proteins to maintain an auxin gradient and root meristem function. This is the first time that a stable change in phyllotactic pattern has been observed in an Arabidopsis mutant, giving a real opportunity to understand regulatory mechanisms underlying behind this developmental process. The PLT genes impaired in this mutant are expressed throughout the shoot apical meristem, i.e. in the peripheral zone where are initiated organ primordia and in the central zone where are lying the stem cells, suggesting a role for PLT genes in establishment of phyllotactic patterns and in shoot apical meristem function. The aim of the project is to understand if PLT genes influence phyllotaxis by controlling auxin polar distribution, as in roots, or / and by regulating meristem size / organisation, the two parameters known to disturb organ positioning.
Оригинален текст от CORDIS (на английски).
Участници
- UNIVERSITEIT UTRECHT · UtrechtКоординаторНидерландия
Връзки
Данни: CORDIS, © Европейски съюз