The regulation of flowering in plants is a extremely complex procedure that is dependent on many internal and international agent . flower at the wrong time point leads to a going of source production and peril the industrial plant ’s reproduction and endurance of the coinage . To combat this problem , plant use a complex electronic connection of protein to unceasingly monitor environmental factors , such as light and temperature , to see the best time point for florescence . The work group of Dr. Vanessa Wahl from the Max Planck Institute of Molecular Plant Physiology , in cooperation with Dr. Anne Krapp from the National Institute for Agricultural Research ( INRA ) in Paris , have now divulge that nitrogen is involved in the regularization of the anthesis time . In March , Dr. Wahl ’s grouping issue their exciting results in the scientific daybook New Phytologist .
Nitrogen is one of the chief food ask for flora growth , and is know to shape various developmental process . Although our air is made up of 78 % molecular N , this gaseous mannequin can not be used by plants . alternatively , plant apply their stem systems to absorb atomic number 7 from the dirt in the form of mineral chemical compound , such as ammonia or nitrate . As industrial plant grow , they step by step deplete N from the soil ; therefore , atomic number 7 fertiliser have to be added to the soil to secure optimal plant growth and yield . If the amount of nitrogen in the soil outmatch the demand of the plant , or if nitrogen can not be absorbed by root due to environmental factors , such as drouth , pregnant amounts of nitrogen are lost from the soil as test - off or leaching to groundwater , lead to environmental pollution . To annul this scenario and promote sustainable farming practices , it is all-important that we gain a elaborated knowledge of how N influences the plant ’s life bicycle , and apply this selective information to manoeuvre and optimise fertilizer covering practices .
After atomic number 7 is absorbed by roots , it is transported through all plant organs by the vascular arrangement . Nitrogen is used as a component in many important biological processes , such as amino acid and protein deduction , and as part of the immature paint chlorophyll , which has an important theatrical role in photosynthesis . Plants grown in nitrogen - depleted soil experience chlorosis and a postponement of growth , which directly results in a monumental takings personnel casualty . In addition to being used as a nutrient , nitrate as the major form of nitrogen is also significant as a signaling molecule . Dr. Vanessa Wahl explains her findings :
“ In the fashion model industrial plant Arabidopsis thaliana , we showed that nitrogen is transfer as nitrate into the shoot apical meristem ( SAM ) to influence inflorescence time . There , the protein SUPRESSOR OF OVEREXPRESSION OF CONSTANS 1 ( SOC1 ) encounter a essential role as a cardinal regulator of flowering at the SAM . SOC1 gene expression is activated by environmental signal like temperature and brightness , or by phytohormones . It is a so - called transcriptional activator , which can pioneer the grammatical construction of other genes . As a result , SOC1 locution cause the industrial plant to bar producing leave and induces bloom . ”
( Upper panel ) genus Arabidopsis plant grow with optimal nitrogen provision ( ON ) are flowering after few workweek with the helper of SOC1 , a central regulator of blossoming , that is produced in the shoot apical meristem ( chicken asterisk ) . ( Lower panel ) If the ground contains low amounts of nitrogen ( LN ) , the flowering of the works is stay and the SOC1 production is contract .
Her group ’s experiments demonstrate that the production of SOC1 is nitrate - dependent . As cogent evidence , plant were grow on N - limited soil and compare to plant grown on full - alimentation soil . Dr. Vanessa Wahl explains : “ The higher the nitrate story of the filth , the more SOC1 was raise , cause plants to blossom earlier . Conversely , under nitrogen - limitation , flowering was detain ” . In addition , nitrate responsive elements ( NREs ) were describe in many gene already known to be involve in the regulation of SOC1 and flowering time . Nitrate can activate these genes , which afterward explains the elevated degree of SOC1 . Finally , it was show for the first time that nitrate is transported into the SAM where it can be metabolized to ammonia . This conversion is mediated by nitrate reductase , found to be present in the SAM . The tissue paper - specific grammatical construction of nitrate reductase was print in the journal Signaling & Behavior in August .
Because inflorescence is an energy - consume summons , the clock time stop of flowering also depends on the availableness of kale , which act as the plant ’s vigor source . In this deference , Dr. Vanessa Wahl bear witness that the sugar trehalose 6 - phosphate ( T6P ) plays an important purpose in flowering , as published by her mathematical group in the daybook Science ( 2013 ) . Interestingly , flowering origination is signaled by T6P and nitrate self-governing from each other . If both signaling are inhibited flowering is not induced .
In sum-up , plant are able to adapt their life cycle depending on the availability of atomic number 7 by retard their flowering time , due to suboptimal growth conditions . Deeper knowledge about the interplay of N and loot perception in terms of flowering time will help to develop new strategies to increase the yield of crop when grown on nitrogen - limited grime . By understanding these biologic mental process , we stand to advance an important approach to optimise the use and program of atomic number 7 fertilizer .
Source : Max Planck Institute of Molecular Plant Physiology
