We examined physiological and growth promotion traits in water-deprived pineapple explants inoculated with two endophytic diazotrophic bacteria. The following questions were addressed: (i) Is the root inoculation efficient to increase bacteria population associated to pineapple explants? (ii) Are nutrient concentrations improved in pineapple explants in response to endophytic bacteria inoculation? (iii) Can endophytic bacteria improve pineapple explants’ growth and photosynthesis? (iv) Is it possible to mitigate water deprivation negative effects and facilitate pineapple explants’ acclimatization using endophytic diazotrophic bacteria? Pineapple ‘Vitória’ explants grown in vitro were inoculated with two different bacteria species. Therefore, 10 mL of bacteria suspension (10⁸ cells mL⁻¹) of either Burkholderia silvatlantica strain UENF 117111 or Herbaspirillum seropedicae strain HRC54 were applied in the substrate after transplantation. Uninoculated explants received 10 mL of autoclaved DYGS liquid medium (Control treatment). These treatments were subdivided in two water regimes, so that explants were either full-irrigated (FI) or non-irrigated (NI) for 24 days. Thereafter, NI explants were re-irrigated to saturation for two days. We found that: (i) The inoculation was efficient to increase bacteria associated to the plantlets; (ii) Nutrient concentrations were not improved in pineapple explants inoculated with both bacteria species; (iii) B. silvatlantica did not change both growth and photosynthetic capacity of the explants. Nonetheless, H. seropedicae inoculation caused negative effects on growth, whereas A_net was increased; (iv) The use of both bacteria delayed water deprivation effects and maintained the photosynthetic capacity through C3 metabolism intact for longer periods under water deprivation, as well as by recovering A_net after re-irrigation.

中文翻译：

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内生重氮细菌在适应过程中减轻了菠萝外植体中的水分缺乏作用

我们检查了接种两种内生重氮营养细菌的缺水菠萝外植体的生理和生长促进特性。解决了以下问题：（i）根部接种对增加与菠萝外植体有关的细菌种群有效吗？（ii）接种内生细菌后，菠萝外植体中的营养物浓度是否提高？（iii）内生细菌可以改善菠萝外植体的生长和光合作用吗？（iv）是否有可能减轻缺水的不利影响并促进使用内生重氮营养细菌的菠萝外植体适应环境？用两种不同的细菌接种体外生长的菠萝“维托里亚”外植体。因此，将10 mL细菌悬浮液（10 ^8个细胞mL ^-1）在移植后将伯克霍尔德氏菌UENF 117111菌株或浆膜草螺旋藻菌株HRC54施用到基质中。未接种的外植体接受10 mL高压灭菌的DYGS液体培养基（对照处理）。这些处理方法分为两种水处理方式，以使外植体全灌（FI）或不灌（NI）24天。之后，将NI外植体再灌溉至饱和状态两天。我们发现：（i）接种有效地增加了与幼苗相关的细菌；（ii）接种两种细菌的​​菠萝外植体中营养物质的浓度均未提高；（iii）B。silvatlantica不会改变外植体的生长和光合能力。尽管如此，接种H. seropedicae对生长造成负面影响，而A _net增加；（iv）两种细菌的​​使用延迟了缺水的作用，并通过在缺水条件下更长的时间内完整地维持C3代谢以及在重新灌溉后恢复A_净来维持光合能力。