RESUMO

BACKGROUND: Gibberellins (GA3) are the most sprayed growth regulator for table grape production worldwide, increasing berry size of seedless varieties through pericarp cell expansion. However, these treatments also exacerbate berry drop, which has a detrimental effect on the postharvest quality of commercialized clusters. Several studies have suggested that pedicel stiffening caused by GA3 would have a role in this disorder. Nevertheless, transcriptional and phenotypic information regarding pedicel responses to GA3 is minimal. RESULTS: Characterization of responses to GA3 treatments using the lines L23 and Thompson Seedless showed that the former was up to six times more susceptible to berry drop than the latter. GA3 also increased the diameter and dry matter percentage of the pedicel on both genotypes. Induction of lignin biosynthesis-related genes by GA3 has been reported, so the quantity of this polymer was measured. The acetyl bromide method detected a decreased concentration of lignin 7 days after GA3 treatment, due to a higher cell wall yield of the isolated fractions of GA3-treated pedicel samples which caused a dilution effect. Thus, an initial enrichment of primary cell wall components in response to GA3 was suggested, particularly in the L23 background. A transcriptomic profiling was performed to identify which genes were associated with these phenotypic changes. This analysis identified 1281 and 1787 genes differentially upregulated by GA3 in L23 and cv. Thompson Seedless, respectively. Concomitantly, 1202 and 1317 downregulated genes were detected in L23 and cv. Thompson Seedless (FDR < 0.05). Gene ontology analysis of upregulated genes showed enrichment in pathways including phenylpropanoids, cell wall metabolism, xylem development, photosynthesis and the cell cycle at 7 days post GA3 application. Twelve genes were characterized by qPCR and striking differences were observed between genotypes, mainly in genes related to cell wall synthesis. CONCLUSIONS: High levels of berry drop are related to an early strong response of primary cell wall synthesis in the pedicel promoted by GA3 treatment. Genetic backgrounds can produce similar phenotypic responses to GA3, although there is considerable variation in the regulation of genes in terms of which are expressed, and the extent of transcript levels achieved within the same time frame.

Assuntos

RESUMO

Most table grape (Vitis vinifera L.) varieties require gibberellic acid (GA3) applications to obtain an adequate berry size in order to satisfy market requirements. However, GA3 treatments also produce severe berry drop in some cultivars, which occurs mainly after a cold storage period during post-harvest. Berry drop in bunches treated with GA3 has been related to the hardening and thickening of the pedicel produced by the over-accumulation of cellulose and its lignification. The main goal of this study was to compare the morphology and gene expression in pedicel samples of genotypes contrasting for berry drop susceptibility. These genotypes are Thompson Seedless, which exhibits a low incidence of berry drop, and a genetic line (Line #23) of INIA's breeding program that is very susceptible to berry drop at harvest and after storage in bunches sprayed with GA3. The parameters measured to study this phenomenon during fruit growth and post-harvest storage included fruit detachment force (FDF), hardness and thickness of the pedicel and berry drop frequency. Histological analyses of pedicel structures at harvest showed an increase in cell size and deposition of lignin in the cortex zone in both contrasting genotypes treated with GA3. The expression profile in both genotypes of the key lignin biosynthesis genes Vv4CL4, VvCCR1L and VvCAD1 analyzed by quantitative real time PCR (qPCR) revealed evident changes in response to GA3 treatments. In particular, gene VvCAD1 is overexpressed (100X) in pedicels of line #23 treated with GA3 after 30 and 45 days in cold storage compared to control. Moreover, the frequency of berry drop was higher for Line #23 treated with GA3 than for the control (23% vs. 1%). Our results suggest that gibberellic acid regulates the expression of the biosynthesis of lignin genes, generating changes in cell wall composition and pedicel structure that result in an increase in berry drop.

Assuntos

RESUMO

The high rate of fruit decay and berry drop reduces quality and increases postharvest losses in "Isabel" grapes, requiring pre-harvest and postharvest management practices available to the small-scale farmer, which maintain quality and extend postharvest life of the clusters. The objective of this study was to evaluate the effect of the pre-harvest application of CaCl2 and Citrus Biomass-based elicitor in "Isabel" grapes, in the maintenance of quality during storage at room conditions under ambient and modified atmospheres. The experiment was conducted in a randomized block design with 8 replicates, in the field located at the municipality of São Vicente Férrer-PE, Brazil. "Isabel" vines were treated 28 days before harvest with: Citrus Biomass-based elicitor (CB), Citrus Biomass-based elicitor + CaCl2 (CB + C), CaCl2 (C) and Control (T) - without application. Grapes harvested in the commercial maturity were stored in a 4 × 2 × 7 factorial arrangement, with 4 treatments (applied in the field), 2 storage conditions, ambient (AA) and modified (AM) atmospheres, under room conditions (25 ± 2 C and 75 ± 2% RH) and 7 evaluation periods in four replicates. The application of CaCl2 and CB-based elicitor reduced the berry drop index (55 and 75%, respectively), the decay and weight loss of "Isabel" grape clusters. These treatments, associated or not, increased MA efficiency in maintaining cluster quality. The ‘Isabel grape berry drop index was directly influenced by the SS/TA ratio, pH and fruit decay index.(AU)

O alto índice de degrana e podridão das bagas reduzem a qualidade e elevam as perdas pós-colheita em uvas Isabel, demandando técnicas de manejo na pré e pós-colheita acessíveis ao pequeno produtor, que mantenham a qualidade e ampliem a vida útil pós-colheita dos cachos. Assim, este trabalho teve por objetivo avaliar o efeito da aplicação na pré-colheita de CaCl2 e elicitor à base de biomassa cítrica em uvas Isabel na manutenção da qualidade durante o armazenamento na condição ambiente sob atmosferas ambiente e modificada. O experimento foi conduzido em blocos casualizados a campo, no município de São Vicente Férrer-PE com 8 repetições. Videiras Isabel foram tratadas, 28 dias antes da colheita, com: elicitor de Biomassa Cítrica (BC), elicitor de Biomassa Cítrica + CaCl2 (BC+C), CaCl2 (C) e Testemunha (T) - sem aplicação. Cachos colhidos na maturação comercial foram armazenados em arranjo fatorial 4×2×7, sendo 4 tratamentos (aplicados no campo), 2 condições de armazenamento, atmosferas ambiente (AA) e modificada (AM), sob condição ambiente (25±2C e 75±2% de UR) e 7 períodos de avaliação em quatro repetições. A aplicação de CaCl2 e do elicitor BC reduziu o índice de degrana (55 e 75%, respectivamente), a podridão e a perda de massa dos cachos de uva Isabel. Estes tratamentos, associados ou não, aumentaram a eficiência da AM em manter a qualidade dos cachos. O índice de degrana (55 e 75%, respectivamente), a podridão e a perda de massa dos cachos de uva ‘Isabel. Estes tratamentos, associados ou não, aumentaram a eficiência da AM em manter a qualidade dos cachos.O índice de degrana de uva ‘Isabel foi influenciado diretamente pela relação SS/AT, pH e índice de podridão das bagas.(AU)

Assuntos

RESUMO

The high rate of fruit decay and berry drop reduces quality and increases postharvest losses in "Isabel" grapes, requiring pre-harvest and postharvest management practices available to the small-scale farmer, which maintain quality and extend postharvest life of the clusters. The objective of this study was to evaluate the effect of the pre-harvest application of CaCl2 and Citrus Biomass-based elicitor in "Isabel" grapes, in the maintenance of quality during storage at room conditions under ambient and modified atmospheres. The experiment was conducted in a randomized block design with 8 replicates, in the field located at the municipality of São Vicente Férrer-PE, Brazil. "Isabel" vines were treated 28 days before harvest with: Citrus Biomass-based elicitor (CB), Citrus Biomass-based elicitor + CaCl2 (CB + C), CaCl2 (C) and Control (T) - without application. Grapes harvested in the commercial maturity were stored in a 4 × 2 × 7 factorial arrangement, with 4 treatments (applied in the field), 2 storage conditions, ambient (AA) and modified (AM) atmospheres, under room conditions (25 ± 2 C and 75 ± 2% RH) and 7 evaluation periods in four replicates. The application of CaCl2 and CB-based elicitor reduced the berry drop index (55 and 75%, respectively), the decay and weight loss of "Isabel" grape clusters. These treatments, associated or not, increased MA efficiency in maintaining cluster quality. The ‘Isabel’ grape berry drop index was directly influenced by the SS/TA ratio, pH and fruit decay index.

O alto índice de degrana e podridão das bagas reduzem a qualidade e elevam as perdas pós-colheita em uvas Isabel, demandando técnicas de manejo na pré e pós-colheita acessíveis ao pequeno produtor, que mantenham a qualidade e ampliem a vida útil pós-colheita dos cachos. Assim, este trabalho teve por objetivo avaliar o efeito da aplicação na pré-colheita de CaCl2 e elicitor à base de biomassa cítrica em uvas Isabel na manutenção da qualidade durante o armazenamento na condição ambiente sob atmosferas ambiente e modificada. O experimento foi conduzido em blocos casualizados a campo, no município de São Vicente Férrer-PE com 8 repetições. Videiras Isabel foram tratadas, 28 dias antes da colheita, com: elicitor de Biomassa Cítrica (BC), elicitor de Biomassa Cítrica + CaCl2 (BC+C), CaCl2 (C) e Testemunha (T) - sem aplicação. Cachos colhidos na maturação comercial foram armazenados em arranjo fatorial 4×2×7, sendo 4 tratamentos (aplicados no campo), 2 condições de armazenamento, atmosferas ambiente (AA) e modificada (AM), sob condição ambiente (25±2C e 75±2% de UR) e 7 períodos de avaliação em quatro repetições. A aplicação de CaCl2 e do elicitor BC reduziu o índice de degrana (55 e 75%, respectivamente), a podridão e a perda de massa dos cachos de uva Isabel. Estes tratamentos, associados ou não, aumentaram a eficiência da AM em manter a qualidade dos cachos. O índice de degrana (55 e 75%, respectivamente), a podridão e a perda de massa dos cachos de uva ‘Isabel’. Estes tratamentos, associados ou não, aumentaram a eficiência da AM em manter a qualidade dos cachos.O índice de degrana de uva ‘Isabel’ foi influenciado diretamente pela relação SS/AT, pH e índice de podridão das bagas.

Assuntos