Trichoderma viride induces phenolics in groundnut (Arachis hypogaea L.) seedlings challenged with rot pathogen (Aspergillus niger Van Tieghem) H. P. Gajera, J. K. Jadav, S. V. Patel & B. A. Golakiya
Phytoparasitica ISSN 0334-2123 Volume 42 Number 5 Phytoparasitica (2014) 42:703-712 DOI 10.1007/s12600-014-0413-6
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Author's personal copy Phytoparasitica (2014) 42:703–712 DOI 10.1007/s12600-014-0413-6
Trichoderma viride induces phenolics in groundnut (Arachis hypogaea L.) seedlings challenged with rot pathogen (Aspergillus niger Van Tieghem) H. P. Gajera & J. K. Jadav & S. V. Patel & B. A. Golakiya
Received: 11 January 2014 / Accepted: 18 May 2014 / Published online: 28 May 2014 # Springer Science+Business Media Dordrecht 2014
Abstract The study showed significant differences in percent collar rot disease incidence in groundnut varieties grown in non-infested soil (T1), challenged with pathogen – Aspergillus niger (T2), and pathogen + Trichoderma viride 60 (T3) treatments. Total phenols revealed a significantly higher content in tolerant varieties (J-11, GG-2) of groundnut compared with moderately susceptible (GAUG-10, GG-13) and susceptible (GG-20) varieties. The phenol content accumulated at a higher rate (193%) in GG-20, followed by GG-2 (146%) and J-11 (107%) varieties during disease development stages. HPLC analysis detected six major phenolics, viz., hydroquinone, gallic, chlorogenic, ferulic, salicylic and cinnamic acids. Among six peaks, hydroquinone was found highest in GG-2 at 3 days in T3. Gallic and salicylic acids increased up to 9 days, while ferulic acid continued to induce up to 15 days in tolerant varieties (J-11, GG-2) of Trichoderma-treated (T3) seedlings. A correlation study indicated that Trichoderma treatment induced five phenolics – except gallic acid – with a higher level of significance in a susceptible variety to reduce disease incidence compared with tolerant varieties. Results demonstrate the T. viride 60 mediated systemic induction of phenolics for biologic control and their probable role in protecting groundnut against A. niger infection.
H. P. Gajera (*) : J. K. Jadav : S. V. Patel : B. A. Golakiya Department of Biotechnology, College of Agriculture, Junagadh Agricultural University, Junagadh, Gujarat 362 001, India e-mail:
[email protected]
Keywords HPLC analysis . Phenolic profile . Trichoderma
Introduction Phenolics are some of the most widespread molecules among plant secondary metabolites, and play a significant role in plant development. They are involved in diverse processes including rhizogenesis (Curir et al. 1990), vitrification (Kevers et al. 1984), resistance to biotic and abiotic stresses (Deladonde et al. 1996), and redox reactions in soils (Takahama & Oniki 1992). They serve as flower pigments, act as constitutive protection agents against invading organisms, function as signal molecules, act as allelopathic compounds, and affect cell and plant growth (Ndakidemi & Dakora 2003). The synthesis and release of phenolics are induced by various biotic and abiotic factors. Tissue injury, pathogen attack, herbivory and infection by microsymbionts such as rhizobium can also cause synthesis and release of phenolics (Lawson et al. 1996). Inside and outside plant tissues, these metabolites are known to function as phytoalexins, phytoanticipins and node gene inducers (Dakora & Phillips 1996, 2002). Phenolics have been known to occur in plants. Some of them occur constitutively, whereas others are formed in response to pathogen ingress and associated as part of an active defense response in the host (Nicholson & Hammerschmidt 1992). The constitutive phenolics are known to confer resistance either directly or indirectly through activation of post-infection responses in the
