Forthcoming Events
Mangroves as natural laboratories for the study of plant adaptations to an extremely dynamic environment
Dr. Ajay Kumar, Assistant Professor, Department of Plant Science, School of Biological Sciences, Central University of Kerala, Kasaragod, India
Location : Online
Abstract: Our lab is currently interested in three broad research themes— understanding mechanisms of mangrove adaptations to the intertidal environment (i), investigation and prospecting of local agrobiodiversity for nutritionally and medicinally important plants (ii), and making sense of plant trait evolution and plant-herbivore interactions using inflated calyx syndrome of Physalis minima and Heliothis subflexa as examples (iii). Therefore, I will cover the results of these three major themes in the seminar presentation along with future research plans, teaching philosophy and plans.
i) Mangroves comprise nearly 70 species of halophytes, occupying intertidal zones between the land and the sea. They are one of the most productive and ecologically important ecosystems on earth. Besides playing several ecological roles, they harbour a rich diversity of organisms. The intertidal environment is highly dynamic and is characterised by very high salinity, hypoxia and submergence stresses. They possess several key adaptations to the intertidal environment, such as ultrafiltration of salt in the roots, stilt roots, pneumatophores, viviparous seed germination, and salt secretory glands in their leaves. These adaptations to the intertidal environment exhibit one of the most fascinating examples of plant evolution to an extremely dynamic environment. However, the genetic and molecular mechanisms underlying these adaptations have been poorly understood. In 2019, we received funding from DST-SERB to investigate these adaptations to the intertidal environment. We use viviparous propagules of Kandelia candel and Rhizophora mucronata to understand their mechanisms for coping with the intertidal environment. Our study demonstrates that both these species may employ certain common and diverging strategies to cope with the dynamic environment. While R. mucronata is a more tolerant species, it enhances the structural rigidity of its root cell walls to increase mechanical resistance against excess salt. This is achieved by enhanced production of lignin and suberin. While K. candel has comparatively lower resistance to salinity stress, it uses transporters more effectively than R. mucronata. Analysis of transcriptome sequencing data shows differential expression of the genes related to lignin biosynthesis and other metabolites, such as flavonoids and taurine, in both species. These results are crucial in advancing our understanding of the mangrove adaptative responses to the fluctuating environment. As mangroves possess tolerance against several stresses such as hypoxia, salinity, and submergence, they are considered natural laboratories for studying extreme plant adaptations that have implications for stress-resilient agriculture.
ii) Many local communities across the globe, including India, still consume locally available food plants, some of which are nutritionally and medicinally important. Through our recent surveys in the Western Ghats, particularly in the Wayanad, Kannur and Kasaragod districts of Kerala, we have identified several (more than 100) underutilised plants possessing nutritional and medicinal potential. Nutritional profiling of nearly 27 plants shows that many of these species are rich in micronutrients and other nutritional components. Further, untargeted metabolite profiling of 14 plants uncover several health-promoting compounds in the selected species. Vitamin profiling of 14 plants further identifies several underutilised species which show higher vitamin C than lemon. Many of these species have been collected from the wild or cultivated near the forests by the local communities for many years. Therefore, they naturally evolve within their natural environments, suggesting their resilience against stress. These species, therefore, hold huge potential in the face of global climate change.
iii) Plant-herbivore interactions demonstrate examples of antagonism. Plants have evolved several mechanisms against herbivory, including spines, thorns, thick cuticles, and secretion of secondary metabolites and non-protein amino acids. Similarly, the genus Physalis belonging to the family Solanaceae, besides synthesising withanolides as defence metabolites, has evolved inflated calyx, a unique example of trait evolution to dodge herbivory. This inflated calyx grows after pollination and completely encircles the fruits. Earlier studies show that inflated calyx is an important defence mechanism against herbivory. However, other studies and our own observations showed that caterpillars of Heliothis subflexa can easily infiltrate these barriers and cause huge damage to the fruits. As these observations did not augur well, we performed a series of experiments to demonstrate whether inflated calyx has a protective role against herbivory or otherwise. The results of this study show that although inflated calyx might have evolved as an important defence against herbivory, it has proved disadvantageous, at least in the case of H. subflexa. H. subflexa uses inflated calyx for its own advantage.
Meeting ID: 946 4466 6106
Passcode: 496593
i) Mangroves comprise nearly 70 species of halophytes, occupying intertidal zones between the land and the sea. They are one of the most productive and ecologically important ecosystems on earth. Besides playing several ecological roles, they harbour a rich diversity of organisms. The intertidal environment is highly dynamic and is characterised by very high salinity, hypoxia and submergence stresses. They possess several key adaptations to the intertidal environment, such as ultrafiltration of salt in the roots, stilt roots, pneumatophores, viviparous seed germination, and salt secretory glands in their leaves. These adaptations to the intertidal environment exhibit one of the most fascinating examples of plant evolution to an extremely dynamic environment. However, the genetic and molecular mechanisms underlying these adaptations have been poorly understood. In 2019, we received funding from DST-SERB to investigate these adaptations to the intertidal environment. We use viviparous propagules of Kandelia candel and Rhizophora mucronata to understand their mechanisms for coping with the intertidal environment. Our study demonstrates that both these species may employ certain common and diverging strategies to cope with the dynamic environment. While R. mucronata is a more tolerant species, it enhances the structural rigidity of its root cell walls to increase mechanical resistance against excess salt. This is achieved by enhanced production of lignin and suberin. While K. candel has comparatively lower resistance to salinity stress, it uses transporters more effectively than R. mucronata. Analysis of transcriptome sequencing data shows differential expression of the genes related to lignin biosynthesis and other metabolites, such as flavonoids and taurine, in both species. These results are crucial in advancing our understanding of the mangrove adaptative responses to the fluctuating environment. As mangroves possess tolerance against several stresses such as hypoxia, salinity, and submergence, they are considered natural laboratories for studying extreme plant adaptations that have implications for stress-resilient agriculture.
ii) Many local communities across the globe, including India, still consume locally available food plants, some of which are nutritionally and medicinally important. Through our recent surveys in the Western Ghats, particularly in the Wayanad, Kannur and Kasaragod districts of Kerala, we have identified several (more than 100) underutilised plants possessing nutritional and medicinal potential. Nutritional profiling of nearly 27 plants shows that many of these species are rich in micronutrients and other nutritional components. Further, untargeted metabolite profiling of 14 plants uncover several health-promoting compounds in the selected species. Vitamin profiling of 14 plants further identifies several underutilised species which show higher vitamin C than lemon. Many of these species have been collected from the wild or cultivated near the forests by the local communities for many years. Therefore, they naturally evolve within their natural environments, suggesting their resilience against stress. These species, therefore, hold huge potential in the face of global climate change.
iii) Plant-herbivore interactions demonstrate examples of antagonism. Plants have evolved several mechanisms against herbivory, including spines, thorns, thick cuticles, and secretion of secondary metabolites and non-protein amino acids. Similarly, the genus Physalis belonging to the family Solanaceae, besides synthesising withanolides as defence metabolites, has evolved inflated calyx, a unique example of trait evolution to dodge herbivory. This inflated calyx grows after pollination and completely encircles the fruits. Earlier studies show that inflated calyx is an important defence mechanism against herbivory. However, other studies and our own observations showed that caterpillars of Heliothis subflexa can easily infiltrate these barriers and cause huge damage to the fruits. As these observations did not augur well, we performed a series of experiments to demonstrate whether inflated calyx has a protective role against herbivory or otherwise. The results of this study show that although inflated calyx might have evolved as an important defence against herbivory, it has proved disadvantageous, at least in the case of H. subflexa. H. subflexa uses inflated calyx for its own advantage.
Meeting ID: 946 4466 6106
Passcode: 496593