Contents lists available at ScienceDirect Scientia Horticulturae journal homepage: www.elsevier.com/locate/scihorti Diversity of Trichoderma species in chili rhizosphere that promote vigor and antagonism against virulent Phytophthora capsici Kiran Nawaz a, ⁎ , Ahmad Ali Shahid a,b , Louis Bengyella c,d, ⁎ , Muhammad Nasir Subhani a , Muhammad Ali a , Waheed Anwar a , Sehrish Iftikhar a , Shinawar Waseem Ali a a Institute of Agricultural Science, University of the Punjab, Lahore, Pakistan b Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan c Department of Plant Pathology, Tree Fruit Research and Extension Center (TFREC), College of Agricultural, Human and Natural Resource Sciences (CAHNRS), Washington State University, USA d Department of Biological Control, Advanced Biotech Cooperative, Cameroon ARTICLE INFO Keywords: Antagonistic activity Root-rot Biocontrol Growth inhibition Phylogeny ABSTRACT The oomycete Phytophthora capsici causes chili pepper (Capsicum annuum L.) blight that is extremely hard to control. In this work, the diversity of Trichoderma species from chili farms and their antagonistic activity against virulent strains of P. capsici were studied. The maximum likelihood phylogenetic analysis based on translation elongation factor 1α (TEF1α) locus revealed divergent evolution in the population structure of Trichoderma species exhibiting antagonistic activities against P. capsici. In vitro confrontation analysis revealed that Trichoderma harzianum, T. viride and T. reesei displayed over 85.5% inhibition of mycelial growth of P. capsici. Furthermore, soil application of Trichoderma species under greenhouse conditions effectively suppressed roo- t–rot severity by 11.24–26.50% (P < 0.05) hallmarked by a significant improvement in mean fresh weights (P = 3.57E-31, F = 486.98, P < 0.05) and length of the roots (P = 3.76E-28, F = 313.51, P < 0.05) compared to controls harboring P. capsici, not inoculated with Trichoderma. We provide evidence of genetic diversity of beneficial Trichoderma species in chili farms having both biocontrol potential against P. capsici coupled with growth promoting properties for chili roots. 1. Introduction Chili pepper (Capsicum annum L.) is an important horticultural economic crop farmed over 19.89 million hectares worldwide (Majid et al., 2016) with an annual yield of 33.52 million tons (Patel, 2014). However, the soil-borne Phytophthora capsici Leonian severely limits chili production even though it is often controlled via fungicide appli- cation, crop rotation, fallow, and even an abandonment of the cropland (Morrison et al., 2011; Wu et al., 2013). P. capsici penetrates the root tissues and cause obstruction in the vascular system that prompt withering, damping-off, foliar blight and fruit rot (Latin and Rane, 1999; Behbudi et al., 2005), leading to an estimated annual loss of $1700–$3200 USD per hectare (Matthew et al., 2006). At times, the occurrence of P. capsici mating types (A1 and A2) in the same farm and their ability to produce infectious oospores that are difficult to eradicate by chemical fungicides calls for alternative control strategies. Additionally, the extensive use of fungicides to combat P. capsici which are expensive and ecologically unfriendly, lead to the development of resistance (Fernández Pavía et al., 2004; Qi et al., 2012; Pang et al., 2013). An alternative to fungicides has been the use of biological control agents (BCA) for the management of P. capsici such as Burkholderia cepacia (Ezziyyani et al., 2004), Pseudomona species (Virgen-Calleros et al., 1997), Glomus intraradices (Zheng et al., 2005), Bacillus species (Guillén-Cruz et al., 2006), uncultured ascomycetes (Robles-Yerena et al., 2010) and Trichoderma species (Li-Destri et al., 2014; Saravanakumar et al., 2016; Jiang et al., 2016; Uniyal and Singh, 2017). Nevertheless, less studies have been performed on the interac- tion of P. capsici with Trichoderma species, although their antagonistic activities on Phytophthora ramorum (Widmer, 2014), P. infestans (Bouziane et al., 2016), P. melonis (Sabbagh et al., 2017) and P. nico- tianae (Ros et al., 2017) are well known. Despite the on-going studies, a few Trichoderma species are known to confer both growth promoting and antagonistic activities for the management of P. capsici in vivo. Additionally, no Trichoderma biodiversity data is available on a chili farming region in Pakistan. In this study, we examine the diversity of Trichoderma species in chili rhizosphere that promote vigor and an- tagonism against virulent invasive P. capsici strains. On the basis of in vitro and greenhouse investigations, it is concluded that T. viride, T. https://doi.org/10.1016/j.scienta.2018.05.048 Received 8 January 2018; Received in revised form 3 May 2018; Accepted 25 May 2018 ⁎ Corresponding authors. E-mail addresses: kirannawaz34@gmail.com (K. Nawaz), louis.bengyella@wsu.edu (L. Bengyella), nasirsubhani.iags@pu.edu.pk (M.N. Subhani). Scientia Horticulturae 239 (2018) 242–252 0304-4238/ © 2018 Published by Elsevier B.V. T