Abstract
Desert truffle is becoming a new crop in semiarid areas. Climatic parameters and the presence of microorganisms influence the host plant physiology and alter desert truffle production. Desert truffle plants present a typical summer deciduous plant phenology divided into four stages: summer dormancy, autumn bud break, winter photosynthetic activity, and spring fruiting. We hypothesize that the bacterial community associated with desert truffle plants will show a seasonal trend linked to their plant growth–promoting rhizobacteria (PGPR) traits. This information will provide us with a better understanding about its potential role in this symbiosis and possible management implementations. Bacteria were isolated from root-adhering soil at the four described seasons. A total of 417 isolated bacteria were phenotypically and biochemically characterized and gathered by molecular analysis into 68 operational taxonomic units (OTUs). They were further characterized for PGPR traits such as indole acetic acid production, siderophore production, calcium phosphate solubilization, and ACCD (1-amino-cyclopropane-1-carboxilatedeaminase) activity. These PGPR traits were used to infer functional PGPR diversity and cultivable bacterial OTU composition at different phenological moments. The different seasons induced shifts in the OTU composition linked to their PGPR traits. Summer was the phenological stage with the lowest microbial diversity and PGPR functions, whereas spring was the most active one. Among the PGPR traits analyzed, P-solubilizing rhizobacteria were harbored in the mycorrhizosphere during desert truffle fruiting in spring.
Highlights
Desert truffle cultivation is becoming a new agricultural activity in semiarid areas of the Iberian Peninsula because of the low water input required for its cultivation (Morte1 3 Vol.:(0123456789)Mycorrhiza pressure deficit (Andrino et al 2019; Marqués-Gálvez et al 2020a)
The effect of seasonality was tested by permutational multivariate analysis of variance (PERMANOVA, (McArdle and Anderson 2001); adonis function, vegan R package)
Desert truffle plants confirmed a very clear phenology along the year with different milestones in autumn, winter, spring, and summer according to the results of this work (Table 1) and as previously reported by Andrino et al (2019) and Marqués-Gálvez et al (2020a, b)
Summary
Desert truffle cultivation is becoming a new agricultural activity in semiarid areas of the Iberian Peninsula because of the low water input required for its cultivation (Morte1 3 Vol.:(0123456789)Mycorrhiza pressure deficit (Andrino et al 2019; Marqués-Gálvez et al 2020a). Photosynthesis begins to increase, reaching its maximum during January–February This period of maximum photosynthesis occurs just before plant blooming and desert truffle fruiting (March–May). We can divide desert truffle plant phenology into four stages: (i) summer dormancy (June–August); (ii) bud break (September–October); (iii) maximal photosynthetic activity (January–February); and (iv) plant blooming and desert truffle fruiting season (March–May). This yearly cycle was shown to be important and necessary for plant fitness and desert truffle production (Morte et al 2012; Honrubia et al 2014)
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