Effect of rhizobium and water regime in plants with extrafloral nectaries: attractiveness of ants, anti-herbivory defense potential and fitness.

• Grant number: 23/11202-5
• Support Opportunities: Scholarships in Brazil - Master
• Start date: October 01, 2023
• Status: Discontinued
• Field of knowledge: Biological Sciences - Botany - Pant Physiology
• Principal Investigator: Anselmo Nogueira
• Grantee: Lucas José Reis Bartsch
• Host Institution: Centro de Ciências Naturais e Humanas (CCNH). Universidade Federal do ABC (UFABC). Ministério da Educação (Brasil). Santo André , SP, Brazil
• Associated research grant: 19/19544-7 - Synergistic effect of multiple mutualists on plants: how bacteria, ants and bees contribute to the evolution of a hyper-diverse lineage of legumes, AP.BTA.JP
• Associated scholarship(s): 24/20233-4 - Temporal variations in carbohydrate allocation in plants: Impact of water stress on mutualistic interactions, BE.EP.MS

Abstract

Mutualisms are interspecific interactions with benefits for both partners, in which mutualistic partners have greater fitness together than when isolated in the environment. However, its effectiveness varies due to the quantity and quality of exchanged resources and the influence of abiotic factors, such as water availability. One of the most common types of mutualism occurs between ants and plants with extrafloral nectaries (EFNs). Ants are attracted to nutrient-rich extrafloral nectar, protecting plants from herbivores and increasing reproductive success. Nutritional mutualism between legumes and nitrogen-fixing bacteria is another case in point, with the bacteria fixing atmospheric nitrogen and the plants providing carbohydrates. However, overlapping different mutualisms in plants of the same species can create conflicts, especially when both partners consume photosynthetic resources. In environments with less water, an increase in conflict is expected, due to the lower efficiency in the production of carbohydrates by plants. Studies on nitrifying bacteria and plant-ant interaction yielded contrasting results. Some show that ants are less attracted to plants with nitrogen-fixing bacteria, while others indicate that plants with rhizobia are more attractive to ants. It is also possible that the benefits of nitrifying bacteria and ants have a synergistic effect, increasing the overall success of the plants. This study aims to investigate how water availability affects the interaction between ants and rhizobial bacteria in plants. To do so, we will use the plant species Chamaecrista nictitans as a model. The seeds will be grown in a greenhouse at UFABC. Pots with seeds will be divided into six experimental conditions, manipulating the presence/absence of rhizobium (two levels) and water availability (three levels). Substrates, seeds and pots will be sterilized with alcohol, bleach and hydrogen peroxide. The "rhizobium" factor will be inoculated with fresh nodule solution. The "water availability" factor will have three levels of soil moisture, to be determined by pilot tests. Our hypotheses are that more humid environments promote a synergistic relationship between ants and rhizobia, favoring the reproductive success of plants. Dry environments, on the other hand, can generate a resource conflict between mutualisms, resulting in variable impacts on ant attraction and plant reproduction, depending on the presence or absence of rhizobia.