Responses to climatic and pathogen threats differ in biodynamic and conventional vines

Abstract

Viticulture is of high socio-economic importance; however, its prevalent practices severely impact the environment and human health, and criticisms from society are raising. Vine managements systems are further challenged by climatic changes. Of the 8 million hectares grown worldwide, conventional and organic practices cover 90% and 9% of acreage, respectively. Biodynamic cultivation accounts for 1%. Although economic success combined with low environmental impact is widely claimed by biodynamic winegrowers from California, to South Africa, and France, this practice is still controversial in viticulture and scientific communities. To rethink the situation, we encouraged stakeholders to confront conventional and biodynamic paradigms in a Participative-Action-Research. Co-designed questions were followed up by holistic comparison of conventional and biodynamic vineyard managements. Here we show that the amplitude of plant responses to climatic threats was higher in biodynamic than conventional management. The same stood true for seasonal trends and pathogens attacks. This was associated with higher expression of silencing and immunity genes, and higher anti-oxidative and anti-fungal secondary metabolite levels. This suggests that sustainability of biodynamic practices probably relies on fine molecular regulations. Such knowledge should contribute to resolving disagreements between stakeholders and help designing the awaited sustainable viticulture at large.

Figure 1

Characterization of conventional and biodynamic viticulture-practices. Data for each month were collected across 2014–2016. Index (modified Treatment Frequency Index) mTFI = product dose used x field surface sprayed/recommended dose x full field surface. Doses are recommended by supplier or/and government for synthetic fungicides in conventional practices (CABRIO TOP, CANTUS, CYFLODIUM, DIAZOLE TL, ELECTIS, ELECTIS BLEU, EMENDO V, HOGGAR, KENKIO, KESIS, MILDICUT, NATIVO, PANTHEOS, PERGADO MZ PEPITE, PROFILER, SWITCH, TALIUS, VIVANDO, YSAYO, (black). Biodynamic composts and preparations (cow manure 500, 500 P, finely ground silica (501), decoctions of nettle (504), willow, horsetail, valerian, and lemon oil, according to Biodynamic guide (green). Copper and Sulfur sprayings in conventional and biodynamic practices (black and green, respectively). Sum of values/year with a bar for each winegrower, black and green for conventional and biodynamic, respectively. Full treatments on vineyards = mTFI + Copper + Sulphur for each time-period.

Figure 2

Proportions of pathogen-free *plants in Pinot Noir grown biodynamic and conventional (green and black, respectively). Data from May and July expressed as % of total plants. In total, 2044 pathogen-free samples out of 2648 collected (2014–2016). *Plants free of powdery and downy mildews, of virus (GFLV, GLRaV 1–3 and GVA), after q-RT-PCR and not showing any symptom described in viticulture.

Figure 3

Climatic characteristics. Data were recorded each 10-day period throughout 2014–2017. Differences between rainfalls and evaporation potential ETP-Penman (bars). Negative values are indicative of water stress. Maximal and minimal temperatures (red and black lines, respectively). Dates for leaf-samples harvest used for molecular and biochemical analysis (black arrows).

Figure 4

Expression levels of silencing and immunity genes in vines grown conventional and biodynamic. (A) Boxplots of Δ.ΔCT of immunity genes calculated for 2014–2016 in leaves pathogen-free n = 2044 (H), infected by powdery and downy mildews, (n = 305) (F), or by at least one virus (GFLV, GLRaV 1–3 and GVA), (n = 263) (V). (B) Boxplots of Δ.ΔCT for silencing genes in pathogen-free (H), infected by fungi (F) and by virus (V), green and black boxes for biodynamic and conventional, respectively. Values statistically different, biodynamic/conventional (Mann-Whitney at *P ≤ 0.05, **P ≤ 0.001, ***P ≤ 0.0001).

Figure 5

Expression levels of silencing and immunity genes in vines grown conventional and biodynamic. (A) PCA analysis for mRNA levels of immunity genes in pathogen-free plants, apoplastic amine oxidases (AOS), Endochitinase 4 C (CHIT4C), Lipase enhanced disease susceptibilty (EDS1), ETR1, Flavonone 3 hydroxylase (F3H), Glutathion S transferase (GST1), HSR, Lipoxygenase (LOX), transcriptional activitors of the sallicic-acid pathway (NPR1-1, NPR1-2), Phenyl alanine ammonia liase (PAL), Pathogenesis related proteins (PR1, PR6, PR10-1), Superoxyde dismutase (SOD), Stilbene synthase (STS1). (B) PCA analysis for mRNA levels of silencing genes in pathogen-free plants: RNA dependent RNA polymerases (RdR-1, RdR-2, RdR-6), MicroRNA-generating (Dicer like DCL1), Small-interfering-RNA-generating (Dicer like DCL2, DCL3, and DCL4), Argonautes (AGO-1, AGO-2, AGO-7), silencing deficient 5 (SDE-5), Supressor of gene silencing 3 (SGS-3), NPRD-1 and HUA Enhancer 1 (HEN-1) (1769 leaves collected in May and July, 2014–2016, on plants free of powdery and downy mildews, of virus (GFLV, GLRaV 1–3 and GVA), and not showing any symptom described in viticulture).

Figure 6

Secondary metabolites contents in leaves of vines grown biodynamic or conventional. (A) Chlorophyll, flavonols and Anthocyans. Box plots (in µg/cm² leaf surface) calculated from 3988 leaf samples measured in May and July 2015–2017 (statistically different, according to Man Whitney at *P ≤ 0.05, **P ≤ 0.001, ***P ≤ 0.0001). Biodynamic and conventional (green and black, respectively). (B–E) Pinot Noir vines grown biodynamic and conventional in May and September (B-C and D-E, respectively).

Figure 7

Secondary metabolites contents in leaves of pathogen-free vines grown biodynamic or conventional. Boxplots analysis of 18 secondary metabolites known in grapevine in mg/g leaf from pathogen-free* plants, after UHPLC-MS analysis, n = 142 collected in July 2014–2016. Values statistically different, biodynamic/conventional (green and black, respectively; Mann Whitney at *P ≤ 0.05, **P ≤ 0.001, ***P ≤ 0.0001). *Plants free of powdery and downy mildews, of virus (GFLV, GLRaV 1–3 and GVA), and not showing any symptom described in viticulture. (A) 2-[4-(3-Hydroxypropyl)-2-methoxyphenoxy]-1,3-propanediol; (B)(−)-Epicatechin; (C) Astragalin; (D) Quercetin 3-O-rutinoside; (G) Astragalin; (H) (−)-Epigallocatechin; (+)-Gallocatechin; (I) Procyanidin trimer EEC; (J) Eriodictyol; (L) (−)-Epigallocatechin; (+)-Gallocatechin; (N) Procyanidin dimer B1; Procyanidin dimer B2; Procyanidin dimer B3; Procyanidin dimer B4; (O) Quercetin 3-glucuronide; (R) Isoquercitrin; Quercetin 3-O-glucoside; (S) Brevilagin; (T) Brevilagin I; (U) 2,4,6-Phenanthrenetriol 2-O-b-D-glucoside; (V) Delphinidin 3-O-glucoside; (Y) (−)-Epigallocatechin 3-O-gallate; (Z) Vitilagin.

Figure 8

Pruning weight of vines grown biodynamic or conventional, (green and black, respectively). Box plots (in kg/plant) calculated from 1120 data from 40 plants in each of the 14 vine plots measured after falls 2016–2017. (Statistically different, according to Mann Whitney ***P ≤ 0.0001).