Sucrose accumulation and endodormancy are synchronized events induced by the short-day photoperiod in grapevine buds.

At the end of the summer season, grapevine buds (Vitis vinifera L) grown in temperate climates enter a state of winter recess or endodormancy (ED), which is induced by the shortening of the photoperiod, and during this period, the buds accumulate sucrose. In this study, we investigated whether the shortening of the photoperiod regulates the accumulation of sucrose in the buds in the same way as it regulates its entry into the ED. Because sucrose accumulation is regulated by genes that control its transport and degradation, the effect of the SD photoperiod and the transition of buds from paradormancy (PD) to ED on the expression of sucrose transporter (VvSUTs) and invertase genes (VvINVs) was studied. To analyze the possible role of sucrose during ED development, its effect on bud swelling and sprouting was studied on dormant and nondormant buds under forced growth conditions. The results showed that the SD photoperiod upregulates the expression of the VvSUT genes and downregulates that of the VvINV genes in grapevine buds. Additionally, during the transition of buds from PD to ED, the sucrose content increased, the expression of the VvINV genes decreased, and the expression of the VvSUT genes did not change significantly. Sucrose delayed bud swelling and sprouting when applied to dormant buds but had no effect when applied to nondormant buds. Therefore, we concluded that ED development and sucrose accumulation were synchronized events induced by the SD photoperiod and that a sucrose peak marks the end of ED development in grapevine buds.

Phenology and fruit set of peach trees cultivated in Dois Vizinhos, Paraná State, Brazil / Fenologia e frutificação efetiva de pessegueiros cultivados em Dois Vizinhos, Paraná

Understanding the dormancy phases and dynamics of commercial cultivars in the regions where they are grown allows for the implementation of different cultural practices and aids in the understanding of the temperature requirements for collaboration with genetic improvement programs. The objective of this study was to determine the budding, flowering, and fruit set rates of peach trees cultivated in the municipality of Dois Vizinhos, Southwestern Paraná, Brazil. The present work was developed using the collection of peach trees in the fruit growing sector of the Universidade Tecnológica Federal do Paraná. Sixteen peach cultivars were evaluated: Rubimel, Leonense, Coral, Marli, Charme, Riograndense, Douradão, Chimarrita, Granada, BR1, Bonão, and Eldorado (all planted in 2009), as well as Regalo, Kampai, Fascínio, and Zilli (planted in 2014). The experimental design was completely randomized with four replications of one plant each, in a 16 × 2 bifactorial arrangement (cultivars × year/harvest). Phenology evaluations were performed weekly by counting open (anthesis) and sprouted flower buds, and the fruit set rate was measured just before fruit thinning. Flowering (%), budding (%), and fruit set (%) rates were calculated. It was found that the year/harvest 2016 promoted the highest rates of sprouting and fruit set. The Bonão cultivar showed greater flowering intensity and regularity in the crop years evaluated (2016 and 2017). Coral and Kampai present fruit sets with greater intensities and regularities when compared to the other cultivars evaluated under the climatic condition of the municipality of Dois Vizinhos. The Riograndense cultivar showed greater irregularity in flowering and fruit production.(AU)

Compreender as fases e a dinâmica da dormência de cultivares comerciais na região em que essa está inserida possibilita a execução de diferentes práticas culturais e auxilia na compreensão dos requisitos de frio e calor exigidos pela mesma, colaborando principalmente com os programas de melhoramento genético. O objetivo deste trabalho foi determinar as taxas de brotação, floração e frutificação efetiva de pessegueiros sob as condições ambientais de cultivo no município de Dois Vizinhos, região Sudoeste do Paraná. O presente trabalho foi desenvolvido na coleção de pessegueiros do setor de Fruticultura da Universidade Tecnológica Federal do Paraná. Foram avaliadas 16 cultivares de pessegueiros, sendo 'Rubimel', 'Leonense', 'Coral, 'Marli', 'Charme', 'Riograndense', 'Douradão', 'Chimarrita', 'Granada', 'BR-1', 'Bonão' e 'Eldorado' implantadas em 2009 e 'Regalo', 'Kampai', 'Fascínio' e 'Zilli', implantadas em 2014. O delineamento experimental foi inteiramente casualizado com quatro repetições de uma planta cada, no arranjo bifatorial 16 x 2 (cultivares x anos/safra). As avaliações de fenologia foram realizadas semanalmente através da contagem de gemas florais abertas (antese) e brotadas, e a taxa de frutificação efetiva foi realizada imediatamente antes do raleio de frutos. Foram calculadas as taxas de floração (%), de brotação (%) e de frutificação efetiva (%). Nas condições climáticas do município de Dois Vizinhos, no Estado do Paraná, verificou-se que o ano/safra 2016 promoveu as maiores taxas de brotação e frutificação efetiva. A cultivar 'Bonão' apresentou maior intensidade e regularidade de floração nos anos safra avaliados (2016 e 2017). As cultivares 'Coral' e 'Kampai' apresentam frutificação efetiva com maior intensidades e regularidade em relação aos demais cultivares avaliados para a condição de clima do local avaliado. A cultivar 'Riograndense' apresentou maior irregularidade na floração e na produção de frutos.(AU)

VvDAM-SVPs genes are regulated by FLOWERING LOCUS T (VvFT) and not by ABA/low temperature-induced VvCBFs transcription factors in grapevine buds.

MAIN CONCLUSION: In deciduous fruit trees in which dormancy is induced by low temperatures, the expression of DORMACY-ASSOCIATED MADS-BOX genes (DAM) is regulated by CBF/DREB1 transcription factors. In Vitis vinifera, in which dormancy is induced by the photoperiod, VvDAM-SVPs gene expression is regulated by FLOWERING LOCUS T (VvFT). Using the sequences of the six peach (Prunus persica) DORMACY-ASSOCIATED MADS-box genes (DAM) as query, eight putative DAM genes belonging to the family of MADS-box transcription factors and related to the Arabidopsis floral regulators SHORT VEGETATIVE PHASE (SVP) and AGAMOUS LIKE 24 (AGL24) were identified in the V. vinifera genome. Among these, five belong to the subfamily SVP-like genes which have been associated with the regulation of flowering and dormancy in annual and perennial plants, respectively. It has been proposed that they play a direct role in the induction and maintenance of endodormancy (ED) through the regulation of the FLOWERING LOCUS T (FT) gene. In the present study, it is demonstrated that in V. vinifera: (1) VvDAM-SVPs genes are not regulated by ABA/low temperature-induced VvCBFs transcription factors as described for other species of deciduous fruit trees. (2) A contrasting expression pattern between VvDAM3-SVP and VvFT was found under different experimental conditions related to the entry and exit of grapevine buds from ED. (3) Overexpression of VvFT in somatic grapevine embryos (SGE) repressed the expression of VvDAM3-SVP and VvDAM4-SVP. Taken together, the results suggest that VvDAM3-SVP could be associated with ED in grapevine buds, and that its expression could be regulated by VvFT.

Induction and overcoming of dormancy of grapevine buds in response to thermal variations in the winter period / Indução e superação da dormência de gemas de videiras em resposta a variações térmicas no período hibernal

This study quantified the chilling requirements for the induction and overcoming of endodormancy (chilling-controlled physiological dormancy) of grapevines buds. Cuttings of the cultivars Chardonnay, Merlot and Cabernet Sauvignon were collected in vineyards in Veranópolis-RS in the winter period of 2019 and 2020. The cuttings were kept at a constant temperature of 7.2 °C or daily cycles of 7.2/18 °C for 6/18 h, 12/12 h or 18/6 h, up to 600 chilling hours (CH). Every 50 CH, part of the cuttings from each treatment was transferred to a temperature of 25 °C for daily assessment of the budburst in the green tip stage. The cultivars had different chilling requirements for inducing and overcoming endodormancy, reaching a total of 150 CH for ‘Chardonnay, 300 CH for ‘Merlot and 400 CH for ‘Cabernet Sauvignon. Of these, 50 CH were required to induce endodormancy in cultivars Chardonnay and Merlot and 100 CH for cultivar Cabernet Sauvignon. Dormancy evolution did not differ between cultivars in response to thermal regimes, with a temperature of 18 °C inert to the accumulation of CH. Precocity and uniformity of budburst were higher after chilling requirements were met during endodormancy for each genotype.(AU)

Este estudo visou quantificar as necessidades de frio para a indução e superação da endodormência (dormência fisiológica controlada por frio) de gemas de videiras. Estacas de das cultivares Chardonnay, Merlot e Cabernet Sauvignon foram coletadas em vinhedos em Veranópolis-RS, no período hibernal de 2019 e 2020. As estacas foram submetidas a temperatura de 7,2 ºC constante ou a ciclos diários de 7,2/18 °C por 6/18 h, 12/12 h ou 18/6 h, até 600 horas de frio (HF). A cada 50 HF, parte das estacas de cada tratamento foi transferida para a temperatura de 25°C, para avaliação diária da brotação das gemas, em estádio de ponta verde. As cultivares tiveram necessidades distintas de frio para indução e superação da endodormência, atingindo um total de 150 HF para ‘Chardonnay, 300 HF para ‘Merlot e 400 HF para ‘Cabernet Sauvignon. Destes totais, 50 HF foram necessárias para indução da endodormência nas cultivares Chardonnay e Merlot e 100 HF na cultivar Cabernet Sauvignon. A evolução da dormência não diferiu entre cultivares em resposta aos regimes térmicos, sendo a temperatura de 18 °C inerte ao acúmulo de HF. A precocidade e uniformidade de brotação das gemas foram maiores após suprido o frio na dormência para cada genótipo.(AU)

Induction and overcoming of dormancy of grapevine buds in response to thermal variations in the winter period / Indução e superação da dormência de gemas de videiras em resposta a variações térmicas no período hibernal

ABSTRACT: This study quantified the chilling requirements for the induction and overcoming of endodormancy (chilling-controlled physiological dormancy) of grapevines buds. Cuttings of the cultivars Chardonnay, Merlot and Cabernet Sauvignon were collected in vineyards in Veranópolis-RS in the winter period of 2019 and 2020. The cuttings were kept at a constant temperature of 7.2 °C or daily cycles of 7.2/18 °C for 6/18 h, 12/12 h or 18/6 h, up to 600 chilling hours (CH). Every 50 CH, part of the cuttings from each treatment was transferred to a temperature of 25 °C for daily assessment of the budburst in the green tip stage. The cultivars had different chilling requirements for inducing and overcoming endodormancy, reaching a total of 150 CH for 'Chardonnay', 300 CH for 'Merlot' and 400 CH for 'Cabernet Sauvignon'. Of these, 50 CH were required to induce endodormancy in cultivars Chardonnay and Merlot and 100 CH for cultivar Cabernet Sauvignon. Dormancy evolution did not differ between cultivars in response to thermal regimes, with a temperature of 18 °C inert to the accumulation of CH. Precocity and uniformity of budburst were higher after chilling requirements were met during endodormancy for each genotype.

RESUMO: Este estudo visou quantificar as necessidades de frio para a indução e superação da endodormência (dormência fisiológica controlada por frio) de gemas de videiras. Estacas de das cultivares Chardonnay, Merlot e Cabernet Sauvignon foram coletadas em vinhedos em Veranópolis-RS, no período hibernal de 2019 e 2020. As estacas foram submetidas a temperatura de 7,2 ºC constante ou a ciclos diários de 7,2/18 °C por 6/18 h, 12/12 h ou 18/6 h, até 600 horas de frio (HF). A cada 50 HF, parte das estacas de cada tratamento foi transferida para a temperatura de 25°C, para avaliação diária da brotação das gemas, em estádio de ponta verde. As cultivares tiveram necessidades distintas de frio para indução e superação da endodormência, atingindo um total de 150 HF para 'Chardonnay', 300 HF para 'Merlot' e 400 HF para 'Cabernet Sauvignon'. Destes totais, 50 HF foram necessárias para indução da endodormência nas cultivares Chardonnay e Merlot e 100 HF na cultivar Cabernet Sauvignon. A evolução da dormência não diferiu entre cultivares em resposta aos regimes térmicos, sendo a temperatura de 18 °C inerte ao acúmulo de HF. A precocidade e uniformidade de brotação das gemas foram maiores após suprido o frio na dormência para cada genótipo.

Induction and overcoming of dormancy of grapevine buds in response to thermal variations in the winter period / Indução e superação da dormência de gemas de videiras em resposta a variações térmicas no período hibernal

This study quantified the chilling requirements for the induction and overcoming of endodormancy (chilling-controlled physiological dormancy) of grapevines buds. Cuttings of the cultivars Chardonnay, Merlot and Cabernet Sauvignon were collected in vineyards in Veranópolis-RS in the winter period of 2019 and 2020. The cuttings were kept at a constant temperature of 7.2 °C or daily cycles of 7.2/18 °C for 6/18 h, 12/12 h or 18/6 h, up to 600 chilling hours (CH). Every 50 CH, part of the cuttings from each treatment was transferred to a temperature of 25 °C for daily assessment of the budburst in the green tip stage. The cultivars had different chilling requirements for inducing and overcoming endodormancy, reaching a total of 150 CH for ‘Chardonnay’, 300 CH for ‘Merlot’ and 400 CH for ‘Cabernet Sauvignon’. Of these, 50 CH were required to induce endodormancy in cultivars Chardonnay and Merlot and 100 CH for cultivar Cabernet Sauvignon. Dormancy evolution did not differ between cultivars in response to thermal regimes, with a temperature of 18 °C inert to the accumulation of CH. Precocity and uniformity of budburst were higher after chilling requirements were met during endodormancy for each genotype.

Este estudo visou quantificar as necessidades de frio para a indução e superação da endodormência (dormência fisiológica controlada por frio) de gemas de videiras. Estacas de das cultivares Chardonnay, Merlot e Cabernet Sauvignon foram coletadas em vinhedos em Veranópolis-RS, no período hibernal de 2019 e 2020. As estacas foram submetidas a temperatura de 7,2 ºC constante ou a ciclos diários de 7,2/18 °C por 6/18 h, 12/12 h ou 18/6 h, até 600 horas de frio (HF). A cada 50 HF, parte das estacas de cada tratamento foi transferida para a temperatura de 25°C, para avaliação diária da brotação das gemas, em estádio de ponta verde. As cultivares tiveram necessidades distintas de frio para indução e superação da endodormência, atingindo um total de 150 HF para ‘Chardonnay’, 300 HF para ‘Merlot’ e 400 HF para ‘Cabernet Sauvignon’. Destes totais, 50 HF foram necessárias para indução da endodormência nas cultivares Chardonnay e Merlot e 100 HF na cultivar Cabernet Sauvignon. A evolução da dormência não diferiu entre cultivares em resposta aos regimes térmicos, sendo a temperatura de 18 °C inerte ao acúmulo de HF. A precocidade e uniformidade de brotação das gemas foram maiores após suprido o frio na dormência para cada genótipo.

ABA Represses the Expression of Cell Cycle Genes and May Modulate the Development of Endodormancy in Grapevine Buds.

Recently, the plant hormone abscisic acid (ABA) has been implicated as a key player in the regulation of endodormancy (ED) in grapevine buds (Vitis vinifera L). In this study, we show that in the vine, the expression of genes related to the biosynthesis of ABA (VvNCED1; VvNCED2) and the content of ABA are significantly higher in the latent bud than at the shoot apex, while the expression of an ABA catabolic gene (VvA8H3) showed no significant difference between either organ. A negative correlation between the content of ABA and transcript levels of cell cycle genes (CCG) was found in both tissues. This result suggested that ABA may negatively regulate the expression of CCG in meristematic tissues of grapevines. To test this proposition, the effect of ABA on the expression of CCG was analyzed in two meristematic tissues of the vine: somatic embryos and shoot apexes. The results indicated that cell cycle progression is repressed by ABA in both organs, since it down-regulated the expression of genes encoding cyclin-dependent kinases (VvCDKB1, VvCDKB2) and genes encoding cyclins of type A (VvCYCA1, VvCYCA2, VvCYCA3), B (VvCYCB), and D (VvCYCD3.2a) and up-regulated the expression of VvICK5, a gene encoding an inhibitor of CDKs. During ED, the content of ABA increased, and the expression of CCG decreased. Moreover, the dormancy-breaking compound hydrogen cyanamide (HC) reduced the content of ABA and up-regulated the expression of CCG, this last effect was abolished when HC and ABA were co-applied. Taken together, these results suggest that ABA-mediated repression of CCG transcription may be part of the mechanism through which ABA modulates the development of ED in grapevine buds.

Cell cycle genes are activated earlier than respiratory genes during release of grapevine buds from endodormancy.

Single-bud cuttings of Vitis vinifera L exposed to forced growing conditions were used to investigate the involvement of phytohormones, abscisic acid (ABA), auxin (Aux) and cytokinin (CK) in the release of buds from the ED and in bud-sprouting. This artificial system imitates and hastens the natural sprouting that occurs in spring. Temporal expression analysis of genes related to phytohormones synthesis, showed an early drop in the expression of ABA biosynthesis gene that preceded an increase in Aux and CK biosynthesis genes. Bud-break is headed by the activation of all structures of the latent bud, especially the differentiation of the inflorescence and the development of the early stages of floral organs. Therefore, resumption of cell division and increases in respiration are essential for the activation of the bud. Temporal expression analysis of the cell cycle and respiration genes indicate that an increase in cell division go before the increase in respiration. These results, together with results indicating that the cell cycle genes are upregulated by Aux and CK, suggest that the events before the bud-break, start with a reduction in ABA content, followed by an increase in the content of Aux and CK, which activates the machinery of the cell cycle, which eventually would cause an increase in respiration.

Garlic extract improves budbreak of the 'Niagara Rosada' grapevines on sub-tropical regions / Extrato de alho melhora a superação da dormência de videiras 'Niagara Rosada' em regiões subtropicais

In the regions with mild winters, usually the chilling requirements for bud dormancy release of grapevines are not fulfilled, and only the highly toxic products CaCN2 (calcium cyanamide) and H2CN2 (hydrogen cyanamide) are recommended in conventional viticulture for budbreak. The purpose of this study was to verify the effect of garlic extract on budbreak of 'Niagara Rosada' grapevines in two different vineyards. The highest dose of garlic extract (70mL L-1) showed a great potential for budbreak in organic production, presenting similar effects of cyanamides in budbreak. This treatment improved the sprouting percentage, number of clusters, accelerated the beginning of sprouting and reduced the cycle between pruning and harvest.

Nas regiões com invernos amenos, normalmente as exigências de frio para a quebra de dormência de gemas de videiras não são atendidas, e apenas os produtos altamente tóxicos CaCN2 e H2CN2 são recomendados na viticultura convencional para quebra de dormência. A proposta deste estudo foi verificar o efeito do extrato de alho na quebra de dormência de videiras 'Niagara Rosada', em dois diferentes vinhedos. A dose mais elevada de extrato de alho (70mL L-1) demonstrou ter um grande potencial para a quebra de dormência na produção orgânica, apresentando efeitos similares aos das cianamidas, na quebra de dormência. Este tratamento aumentou a porcentagem de brotação e o número de cachos, antecipou o começo da brotação e reduziu o ciclo entre poda e colheita.

Garlic extract improves budbreak of the 'Niagara Rosada' grapevines on sub-tropical regions

In the regions with mild winters, usually the chilling requirements for bud dormancy release of grapevines are not fulfilled, and only the highly toxic products CaCN2 (calcium cyanamide) and H2CN2 (hydrogen cyanamide) are recommended in conventional viticulture for budbreak. The purpose of this study was to verify the effect of garlic extract on budbreak of 'Niagara Rosada' grapevines in two different vineyards. The highest dose of garlic extract (70mL L-1) showed a great potential for budbreak in organic production, presenting similar effects of cyanamides in budbreak. This treatment improved the sprouting percentage, number of clusters, accelerated the beginning of sprouting and reduced the cycle between pruning and harvest.

Nas regiões com invernos amenos, normalmente as exigências de frio para a quebra de dormência de gemas de videiras não são atendidas, e apenas os produtos altamente tóxicos CaCN2 e H2CN2 são recomendados na viticultura convencional para quebra de dormência. A proposta deste estudo foi verificar o efeito do extrato de alho na quebra de dormência de videiras 'Niagara Rosada', em dois diferentes vinhedos. A dose mais elevada de extrato de alho (70mL L-1) demonstrou ter um grande potencial para a quebra de dormência na produção orgânica, apresentando efeitos similares aos das cianamidas, na quebra de dormência. Este tratamento aumentou a porcentagem de brotação e o número de cachos, antecipou o começo da brotação e reduziu o ciclo entre poda e colheita.

Garlic extract improves budbreak of the 'Niagara Rosada' grapevines on sub-tropical regions

In the regions with mild winters, usually the chilling requirements for bud dormancy release of grapevines are not fulfilled, and only the highly toxic products CaCN2 (calcium cyanamide) and H2CN2 (hydrogen cyanamide) are recommended in conventional viticulture for budbreak. The purpose of this study was to verify the effect of garlic extract on budbreak of 'Niagara Rosada' grapevines in two different vineyards. The highest dose of garlic extract (70mL L-1) showed a great potential for budbreak in organic production, presenting similar effects of cyanamides in budbreak. This treatment improved the sprouting percentage, number of clusters, accelerated the beginning of sprouting and reduced the cycle between pruning and harvest.

Nas regiões com invernos amenos, normalmente as exigências de frio para a quebra de dormência de gemas de videiras não são atendidas, e apenas os produtos altamente tóxicos CaCN2 e H2CN2 são recomendados na viticultura convencional para quebra de dormência. A proposta deste estudo foi verificar o efeito do extrato de alho na quebra de dormência de videiras 'Niagara Rosada', em dois diferentes vinhedos. A dose mais elevada de extrato de alho (70mL L-1) demonstrou ter um grande potencial para a quebra de dormência na produção orgânica, apresentando efeitos similares aos das cianamidas, na quebra de dormência. Este tratamento aumentou a porcentagem de brotação e o número de cachos, antecipou o começo da brotação e reduziu o ciclo entre poda e colheita.

Garlic extract improves budbreak of the 'Niagara Rosada' grapevines on sub-tropical regions

In the regions with mild winters, usually the chilling requirements for bud dormancy release of grapevines are not fulfilled, and only the highly toxic products CaCN2 (calcium cyanamide) and H2CN2 (hydrogen cyanamide) are recommended in conventional viticulture for budbreak. The purpose of this study was to verify the effect of garlic extract on budbreak of 'Niagara Rosada' grapevines in two different vineyards. The highest dose of garlic extract (70mL L-1) showed a great potential for budbreak in organic production, presenting similar effects of cyanamides in budbreak. This treatment improved the sprouting percentage, number of clusters, accelerated the beginning of sprouting and reduced the cycle between pruning and harvest.

Nas regiões com invernos amenos, normalmente as exigências de frio para a quebra de dormência de gemas de videiras não são atendidas, e apenas os produtos altamente tóxicos CaCN2 e H2CN2 são recomendados na viticultura convencional para quebra de dormência. A proposta deste estudo foi verificar o efeito do extrato de alho na quebra de dormência de videiras 'Niagara Rosada', em dois diferentes vinhedos. A dose mais elevada de extrato de alho (70mL L-1) demonstrou ter um grande potencial para a quebra de dormência na produção orgânica, apresentando efeitos similares aos das cianamidas, na quebra de dormência. Este tratamento aumentou a porcentagem de brotação e o número de cachos, antecipou o começo da brotação e reduziu o ciclo entre poda e colheita.