16The biocontrol fungus, Pochonia chlamydosporia, colonizes endophytically banana 17 roots. Root hairs and root surface were found colonize by the fungus using a stable GFP 18 transformant. Hyphal penetration of root cells was also observed. Spores of P. 19 chlamydosporia 123, significantly increase root and leaf length and weight in banana 20 plantlets (Musa acuminata cv. 'Dwarf Cavendish') in growth chamber experiments 30 21 days post-inoculation (dpi). In greenhouse 8L pot experiments, P. chlamydosporia 123 22 spore inoculation significantly increases leaf and root length and leaf weight in banana 23 plants (75 dpi). Spore inoculation of P. chlamydosporia strains from worldwide origin 24 (Pc21 Italy, Pc123 Spain, Pc399 China, and Pccat Cuba), significantly increases root, 25 corm and leaf length and weight in banana plantlets. Pc21 was the best colonizer of 26 banana roots. Consequently, this strain significantly increases most banana root and leaf 27 length. Root colonization by P. chlamydosporia was also detected using cultural 28 techniques and qPCR. 29 30 KEYWORDS 31 Banana, Root colonization, Pochonia chlamydosporia, Musa acuminata, Growth 32 promotion, Endophyte. 33 34 35 36 37 38 3 65 (Bordallo et al., 2002; Macia-Vicent et al., 2009a). All these properties make this 66 fungus a good candidate for banana plant biomanagement.
67In this work, we devise a new method for inoculating Pc123 in banana plants. 68 We also test worldwide Pc strains to determine the effect of fungus genetic variation in 69 plant growth promotion and root colonization. 70 71 72 4 2. MATERIALS AND METHODS 73 2.1 Plants and fungi 74 In vitro 30-day-old banana plantlets (Musa acuminata cv. 'Dwarf Cavendish' 75 AAA) were obtained from Cultesa (Santa Cruz de Tenerife, Canary Islands, Spain). 76 Before experiments, plantlets were acclimatized in a growth chamber (SANYO MLR-77 351H) for 5-10 days, at 24 °C, 60% relative humidity and 16h/8h light/darkness 78 photoperiod. 79 Pc21, Pc123, Pc399 and Pccat strains from the nematophagous fungus Pochonia 80 chlamydosporia (Pc) were obtained from the Collection of the Phytopathology 81 Laboratory (University of Alicante, Spain). Pc21 was isolated in Metaponto (Italy) from 82 Meloidogyne sp. in kiwi trees (Macia-Vicent et al., 2009a) and was a kind gift from Dr. 83 A. Ciancio (CNR, Bari, Italy). Pc123 was isolated from Heterodera avenae eggs in 84 southwest Spain (Olivares-Bernabeu & Lopez-Llorca, 2002). Pc399 was obtained in 85 China by late Professor Brian Kerry (Rothamsted Research, UK), who kindly sent us 86 the strain for research purposes. Pccat was isolated from Meloidogyne spp. infected eggs 87 in Cuba (Zavala et al., 2015) and was a kind gift from Dr. L. Hidalgo (CENSA, Cuba).88 2.2 Growth chamber experiments 89 Plantlets were grown individually in 200 ml polystyrene cups with sterilized 90 Terraplant 2 peat (Compo Expert, Castellón, Spain). The experiment included three 91 treatments with Pc123 and control. Treatment 1 consisted of plantlets inoculated with 92 eight 5mm diameter c...
