Diversity, Quorum Sensing, and Plant Growth Promotion by Endophytic Diazotrophs Associated with Sugarcane with Special R

Endophytic bacteria are widely distributed among plants and colonize both intracellular and intercellular spaces and do not harm the host plant. However, the distributions of endophytic diazotrophs are limited. Endophytic diazotrophs like Gluconacetobacte

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Iqbal Ahmad, Mohd. Musheer Altaf, Jyoti Sharma, and Abdullah Safar Al-thubiani

Abstract

Endophytic bacteria are widely distributed among plants and colonize both intracellular and intercellular spaces and do not harm the host plant. However, the distributions of endophytic diazotrophs are limited. Endophytic diazotrophs like Gluconacetobacter diazotrophicus are mainly associated with sugarcane and some other plants and responsible for significant contribution of biological nitrogen fixation with sugarcane. In this article, we described the diversity and role of quorum sensing. We also discussed the contributions of different bacterial traits that are necessary for successful colonization of the plant interior part. Further mechanisms of plant growth promotion are elaborated. Molecular characterization and identification of endophytic diazotrophs will further help in better understanding of plant colonization and plant growth promotion.

I. Ahmad • M.M. Altaf (*) Department of Agricultural Microbiology, Aligarh Muslim University, Aligarh 202002, India e-mail: [email protected] J. Sharma Department of Science and Technology, Technology Bhavan, New Delhi 110016, India A.S. Al-thubiani Department of Biology, School of Applied Science, Umm Al-Qura University, Makkah 21955, Saudi Arabia © Springer Nature Singapore Pte Ltd. 2016 D.K. Choudhary et al. (eds.), Plant-Microbe Interaction: An Approach to Sustainable Agriculture, DOI 10.1007/978-981-10-2854-0_23

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23.1 Introduction The Green Revolution had increased the agricultural productivity to a great extent by the increased application of high-yielding crop varieties, heavy farm equipments, synthetic fertilizers, pesticides, improved irrigation, better soil administration, and massive conversion of forest to agricultural lands (Tilman et al. 2002; Gomiero et al. 2011). But there is a growing apprehension that intensive practices employed for increasing agricultural output promote ecosystem deterioration and loss of yield. Adverse environmental effects include deforestation, soil degradation, large-scale greenhouse gas emissions, accumulation of pesticides and chemical fertilizers, pollution of groundwater, and decreased water table due to excessive irrigation (Tilman et al. 2002; Foley et al. 2011). The International Fertilizer Industry Association (IFA) agriculture committee projected that the global fertilizer consumption is expected to grow, and it will reach 199.4 million metric tons (Mt) of nutrients in 2019 (Heffer and Prud’homme 2015). The projected increase will be at the rate of 1.3, 2.1, and 2.4 % for nitrogen, phosphorus, and potassium, respectively. In reality, an intensive agricultural practice is considered to be the main source of loss of global biodiversity. Traditional agricultural practices like organic farming, which considerably decrease the input of chemical fertilizers, pesticides, energy, and mechanic stress, help us in extenuating the harmful effects of intensive agricultural practices and simultaneously boost