Lack of Linkages among Fruiting Depth, Weight, and Maturity in Irrigated Truffle Fungi Marks the Complexity of Relationships among Morphogenetic Stages

Abstract

The highly prized black truffle (Tuber melanosporum) has become a model species for ectomycorrhizal fungi biology. However, several questions concerning its reproductive phase remain unanswered. To provide new hypotheses on the fruitbody formation process, we have explored the causal links among development characters of black truffle fruitbodies that are primarily linked to either the mating process, fruitbody growing stage, or maturation. Path analysis was applied to test causal models outlining the relationships among fruitbody development characters such as fruiting depth, weight, shape, and spore maturity. These characters were investigated over a two-season survey and three soil typologies (plus peat-based substrate) under irrigated conditions. We found a clear and generalized relationship between fruitbody weight and shape. Among clusters of fruitbodies we found a positive relationship between the weight of the largest fruitbody and the weight of the remaining fruitbodies. However, no generalized relationships among characters linked to different development stages appeared. Our results were noticeably consistent across soil typologies, both for fruitbodies growing singly and in clusters, indicating that early-developing fruitbody characters did not influence characters linked to subsequent morphogenetic stages. The lack of links among stages opens new perspectives for pre-harvest quality management with stage-specific cultivation practices.

Heterogeneity of the white truffle Tuber magnatum in a limited geographic area of Central‐Southern Italy

“…aestivum (Büntgen et al ., 2017) and T . melanosporum (Garcia‐Barreda et al ., 2021), which revealed the absence of a causal link between ascocarp ripeness and size. Indeed, small truffles can be ripe while large truffles can be immature (Büntgen et al ., 2017; Garcia‐Barreda et al ., 2021).…”

“…Indeed, small truffles can be ripe while large truffles can be immature (Büntgen et al ., 2017; Garcia‐Barreda et al ., 2021). Moreover, there is no evidence that ascocarps must reach a minimum size to mature or that weight gain and ripeness evolve together (Garcia‐Barreda et al ., 2021). The absence of correlation between weight and maturity differentiates truffles from some epigeous fungi, for which species‐specific size‐ripeness associations are reported (Büntgen et al ., 2017).…”

“…These findings are in line with the investigations previously carried out on T. aestivum (Büntgen et al, 2017) and T. melanosporum (Garcia-Barreda et al, 2021), which revealed the absence of a causal link between ascocarp ripeness and size. Indeed, small truffles can be ripe while large truffles can be immature (Büntgen et al, 2017;Garcia-Barreda et al, 2021). Moreover, there is no evidence that ascocarps must reach a minimum size to mature or that weight gain and ripeness evolve together (Garcia-Barreda et al, 2021).…”

Black Truffle Aroma Evaluation: SPME-GC-MS vs. Sensory Experts

“…These molecules were previously found in T. melanosporum truffles [ 1 , 7 ]. Truffle maturity changes can be observed in the spore maturity [ 27 ], chemical composition [ 28 ], and bacterial community profile [ 29 , 30 ] throughout the season. As indicated by Caboni et al (2020) [ 31 ], metabolite levels in truffles strongly depend on the month of harvesting which is directly related to the maturity stage.…”

Eco-archaeological excavation techniques reveal snapshots of subterranean truffle growth

“…Comparison of our results with those from other Tuber species is problematic since most of them have much shorter growing seasons and likely only one life cycle. For example, Tuber melanosporum commonly, but not exclusively (Rebière, 1967), fruits in its Mediterranean habitats from the end of December until early March (Callot, 1999;Garcia-Barreda et al, 2021), and only small and unripe primordia between 0.5-1.0 mm have been described to form in summer and autumn (Pradel, 1914;Pacioni et al, 2014). It has been reported that several months are needed from the induction and initial production of primordia to fully mature Tuber melanosporum fruitbodies (Pacioni et al, 2014;Le Tacon et al, 2013;Garcia-Barreda et al, 2021).…”