Ethylene responsive element binding factors contributes to waterlogging tolerance by regulating photosynthetic and physiological parameters in petunia / Os fatores de ligação do elemento responsivo ao etileno contribuem para a tolerância ao encharcamento, regulando os parâmetros fotossintéticos e fisiológicos na petúnia

Ethylene-responsive element binding factors (ERFs) are widely involved in the regulation of plant responses to different abiotic stresses. In petunia (Petunia × hybrida), PhERF2 belonging to the subfamily Ⅶ of ERF transcription factors participates in the response to waterlogging stress. In this study, we investigated waterlogging tolerance variation of WT and transgenic petunia plants with RNAi silencing and overexpression of PhERF2 through photosynthetic and physiological performance. Chlorophyll content and root vigor declined continuously in both WT and PhERF2 transgenic lines under waterlogging stress, but the extent of the fall in PhERF2-overexpressing lines was less than that in WT and PhERF2-RNAi lines. At the end of waterlogging treatment, soluble protein levels in PhERF2-overexpressing lines were significantly higher than those in WT and PhERF2-RNAi lines, while the latter showed a higher malondialdehyde content overall. Different degrees of reductions in Pn, Gs, and Tr levels occurred in both WT and PhERF2 transgenic lines upon exposure to waterlogging. The Ci levels of PhERF2-overexpressing lines decreased after 3 hours of waterlogging treatment, and the Ci levels of WT and PhERF2-RNAi lines gradually increased from 6 to 72 hours of waterlogging treatment. These data suggested that non-stomatal factors were the primary limiting factors for Pn in WT and PhERF2-RNAi lines under severe stress, while the stomatal opening was the main factor limiting Pn in PhERF2-overexpressing lines. Our results demonstrated that the contribution of PhERF2 to the waterlogging tolerance of petunia appears to depend on the regulation of physiological and photosynthetic responses. PhERF2 represents a hopeful candidate gene for enhancing waterlogging tolerance of ornamental plants.

Fatores de transcrição de resposta ao etileno (ERF) estão amplamente envolvidos na regulação das respostas das plantas a diferentes estresses abióticos. Em petúnia (Petunia × hybrida), PhERF2 pertencente à subfamília Ⅶ de fatores de transcrição ERF participa da resposta ao estresse de alagamento. Este estudo teve como objetivo investigar a variação da tolerância ao alagamento de plantas WT e petúnia transgênica com silenciamento de RNAi e superexpressão de PhERF2 através do desempenho fotossintético e fisiológico. O conteúdo de clorofila e o vigor da raiz diminuíram continuamente em ambas as linhagens transgênicas WT e PhERF2 sob estresse de alagamento, mas a extensão da queda nas linhas de superexpressão de PhERF2 foi menor do que nas linhas WT e PhERF2-RNAi. No final do tratamento de alagamento, os níveis de proteína solúvel nas linhas com superexpressão de PhERF2 foram significativamente maiores do que nas linhas WT e PhERF2-RNAi, enquanto a última mostrou um teor geral de malondialdeído maior. Diferentes graus de reduções nos níveis de Pn, Gs e Tr ocorreram em ambas as linhas transgênicas WT e PhERF2 após a exposição ao alagamento. Os níveis de Ci das linhas de superexpressão de PhERF2 diminuíram após três horas de tratamento de alagamento, e os níveis de Ci das linhas de WT e PhERF2-RNAi aumentaram gradualmente de seis para 72 horas de tratamento de alagamento. Esses dados sugeriram que os fatores não estomáticos foram os principais fatores limitantes para Pn em linhas WT e PhERF2-RNAi sob estresse severo, enquanto a abertura estomática foi o principal fator limitante de Pn em linhas com superexpressão de PhERF2. Nossos resultados demonstraram que a contribuição do PhERF2 para a tolerância ao alagamento da petúnia parece depender da regulação das respostas fisiológicas e fotossintéticas. PhERF2 representa um gene candidato esperançoso no aumento da tolerância ao alagamento de plantas ornamentais.

Ethylene responsive element binding factors contributes to waterlogging tolerance by regulating photosynthetic and physiological parameters in petunia / Os fatores de ligação do elemento responsivo ao etileno contribuem para a tolerância ao encharcamento, regulando os parâmetros fotossintéticos e fisiológicos na petúnia

ABSTRACT: Ethylene-responsive element binding factors (ERFs) are widely involved in the regulation of plant responses to different abiotic stresses. In petunia (Petunia × hybrida), PhERF2 belonging to the subfamily Ⅶ of ERF transcription factors participates in the response to waterlogging stress. In this study, we investigated waterlogging tolerance variation of WT and transgenic petunia plants with RNAi silencing and overexpression of PhERF2 through photosynthetic and physiological performance. Chlorophyll content and root vigor declined continuously in both WT and PhERF2 transgenic lines under waterlogging stress, but the extent of the fall in PhERF2-overexpressing lines was less than that in WT and PhERF2-RNAi lines. At the end of waterlogging treatment, soluble protein levels in PhERF2-overexpressing lines were significantly higher than those in WT and PhERF2-RNAi lines, while the latter showed a higher malondialdehyde content overall. Different degrees of reductions in Pn, Gs, and Tr levels occurred in both WT and PhERF2 transgenic lines upon exposure to waterlogging. The Ci levels of PhERF2-overexpressing lines decreased after 3 hours of waterlogging treatment, and the Ci levels of WT and PhERF2-RNAi lines gradually increased from 6 to 72 hours of waterlogging treatment. These data suggested that non-stomatal factors were the primary limiting factors for Pn in WT and PhERF2-RNAi lines under severe stress, while the stomatal opening was the main factor limiting Pn in PhERF2-overexpressing lines. Our results demonstrated that the contribution of PhERF2 to the waterlogging tolerance of petunia appears to depend on the regulation of physiological and photosynthetic responses. PhERF2 represents a hopeful candidate gene for enhancing waterlogging tolerance of ornamental plants.

RESUMO: Fatores de transcrição de resposta ao etileno (ERF) estão amplamente envolvidos na regulação das respostas das plantas a diferentes estresses abióticos. Em petúnia (Petunia × hybrida), PhERF2 pertencente à subfamília Ⅶ de fatores de transcrição ERF participa da resposta ao estresse de alagamento. Este estudo teve como objetivo investigar a variação da tolerância ao alagamento de plantas WT e petúnia transgênica com silenciamento de RNAi e superexpressão de PhERF2 através do desempenho fotossintético e fisiológico. O conteúdo de clorofila e o vigor da raiz diminuíram continuamente em ambas as linhagens transgênicas WT e PhERF2 sob estresse de alagamento, mas a extensão da queda nas linhas de superexpressão de PhERF2 foi menor do que nas linhas WT e PhERF2-RNAi. No final do tratamento de alagamento, os níveis de proteína solúvel nas linhas com superexpressão de PhERF2 foram significativamente maiores do que nas linhas WT e PhERF2-RNAi, enquanto a última mostrou um teor geral de malondialdeído maior. Diferentes graus de reduções nos níveis de Pn, Gs e Tr ocorreram em ambas as linhas transgênicas WT e PhERF2 após a exposição ao alagamento. Os níveis de Ci das linhas de superexpressão de PhERF2 diminuíram após três horas de tratamento de alagamento, e os níveis de Ci das linhas de WT e PhERF2-RNAi aumentaram gradualmente de seis para 72 horas de tratamento de alagamento. Esses dados sugeriram que os fatores não estomáticos foram os principais fatores limitantes para Pn em linhas WT e PhERF2-RNAi sob estresse severo, enquanto a abertura estomática foi o principal fator limitante de Pn em linhas com superexpressão de PhERF2. Nossos resultados demonstraram que a contribuição do PhERF2 para a tolerância ao alagamento da petúnia parece depender da regulação das respostas fisiológicas e fotossintéticas. PhERF2 representa um gene candidato esperançoso no aumento da tolerância ao alagamento de plantas ornamentais.

Seedlings production of Gomphrena globosa and Petunia x hybridain different times and substrates / Produção de mudas de Gomphrena globosa e Petunia x hybrida em diferentes épocas e substratos

This study aimed to evaluate the seedlings growth of Petunia x hybridaand Gomphrena globose at different times and substrates based on agricultural residues. A completely randomized experimental design was adopted, in a factorial scheme, with treatments consisting of four replications and the experimental unit formed by ten plants. The flower species Petunia x hybridaand G. globosawere cultivated in five substrate compositions and in two seasons, with sowing carried out in April and June for Petunia x hybrid and April and October for G. globosa. The substrates were composed using commercial substrate (CM), bovine manure (BM), worm humus (WM) and rice husk ash (HA), in volumetric proportions: (S1) 100% CS; (S2) 40% CS + 20% BM + 20% WH + 20% HA; (S3) 60% CS + 20% WH + 20% HA; (S4) 60% CS + 20% BM + 20% HA; and (S5) 80% CS + 20% BM. Emergence, emergence speed index, height, number of leaves, length of the largest leaf, length of the largest root, dry mass of the aboveground part, dry mass of the root system and total dry mass were evaluated. The seedlings growth of the Petunia x hybridaand G. globosa changed according to the characteristics of the substrates and the growing seasons. The substrate composed with 80% commercial substrate and 20% bovine manure showed similar or superior results to the commercial substrate and can be used in order to reduce production costs without prejudice to the seedlings growth. The cultivation of Petunia x hybridain April resulted in seedlings with greater height, leaf length and greater accumulation of phytomass. The G. globosa seedlings showed greater development of the aboveground part and the root system, in addition to greater accumulation of phytomass when cultivated in October.

Objetivou-se avaliar o crescimento de mudas de Petunia x hybridae Gomphrena globosa cultivadas em diferentes épocas e substratos a base de resíduos agropecuários. O delineamento experimental utilizado foi o inteiramente casualizado, em esquema fatorial, sendo os tratamentos compostos por quatro repetições e a unidade experimental formada por dez plantas. Foram cultivadas as espécies de flores Petunia x hybridae G. globosa em cinco composições de substratos e em duas épocas, sendo as semeaduras realizadas em abril e junho para a Petunia x hybridae abril e outubro para a G. globosa. Os substratos foram compostos utilizando-se substrato comercial (CS), esterco bovino curtido (BM), húmus de minhoca (WH) e cinza de casca de arroz (HA), nas proporções volumétricas: (S1) 100% CS; (S2) 40% CS + 20% BM + 20% WH + 20% HA; (S3) 60% CS + 20% WH + 20% HA; (S4) 60% CS + 20% BM + 20% HA; e (S5) 80% CS + 20% BM. Avaliou-se a emergência, índice de velocidade de emergência, altura, número de folhas, comprimento da maior folha, comprimento da maior raiz, massa seca da parte aérea, massa seca do sistema radicular e massa seca total. O crescimento das mudas de Petunia x hybridae G. globosa modificou-se conforme as características dos substratos e as épocas de cultivo. O substrato composto com 80% de substrato comercial e 20% de esterco bovino apresentou resultados semelhantes ou superiores ao substrato comercial, podendo ser utilizado a fim de reduzir os custos de produção sem prejuízos ao crescimento das mudas. O cultivo de Petunia x hybridaem abril resultou em mudas com maior altura, comprimento das folhas e maior acúmulo de fitomassa. As mudas de G. globosa apresentaram maior desenvolvimento da parte aérea e do sistema radicular, além de maior acúmulo de fitomassa quando cultivadas em outubro.

Seedlings production of Gomphrena globosa and Petunia x hybridain different times and substrates / Produção de mudas de Gomphrena globosa e Petunia x hybrida em diferentes épocas e substratos

This study aimed to evaluate the seedlings growth of Petunia x hybridaand Gomphrena globose at different times and substrates based on agricultural residues. A completely randomized experimental design was adopted, in a factorial scheme, with treatments consisting of four replications and the experimental unit formed by ten plants. The flower species Petunia x hybridaand G. globosawere cultivated in five substrate compositions and in two seasons, with sowing carried out in April and June for Petunia x hybrid and April and October for G. globosa. The substrates were composed using commercial substrate (CM), bovine manure (BM), worm humus (WM) and rice husk ash (HA), in volumetric proportions: (S1) 100% CS; (S2) 40% CS + 20% BM + 20% WH + 20% HA; (S3) 60% CS + 20% WH + 20% HA; (S4) 60% CS + 20% BM + 20% HA; and (S5) 80% CS + 20% BM. Emergence, emergence speed index, height, number of leaves, length of the largest leaf, length of the largest root, dry mass of the aboveground part, dry mass of the root system and total dry mass were evaluated. The seedlings growth of the Petunia x hybridaand G. globosa changed according to the characteristics of the substrates and the growing seasons. The substrate composed with 80% commercial substrate and 20% bovine manure showed similar or superior results to the commercial substrate and can be used in order to reduce production costs without prejudice to the seedlings growth. The cultivation of Petunia x hybridain April resulted in seedlings with greater height, leaf length and greater accumulation of phytomass. The G. globosa seedlings showed greater development of the aboveground part and the root system, in addition to greater accumulation of phytomass when cultivated in October.(AU)

Objetivou-se avaliar o crescimento de mudas de Petunia x hybridae Gomphrena globosa cultivadas em diferentes épocas e substratos a base de resíduos agropecuários. O delineamento experimental utilizado foi o inteiramente casualizado, em esquema fatorial, sendo os tratamentos compostos por quatro repetições e a unidade experimental formada por dez plantas. Foram cultivadas as espécies de flores Petunia x hybridae G. globosa em cinco composições de substratos e em duas épocas, sendo as semeaduras realizadas em abril e junho para a Petunia x hybridae abril e outubro para a G. globosa. Os substratos foram compostos utilizando-se substrato comercial (CS), esterco bovino curtido (BM), húmus de minhoca (WH) e cinza de casca de arroz (HA), nas proporções volumétricas: (S1) 100% CS; (S2) 40% CS + 20% BM + 20% WH + 20% HA; (S3) 60% CS + 20% WH + 20% HA; (S4) 60% CS + 20% BM + 20% HA; e (S5) 80% CS + 20% BM. Avaliou-se a emergência, índice de velocidade de emergência, altura, número de folhas, comprimento da maior folha, comprimento da maior raiz, massa seca da parte aérea, massa seca do sistema radicular e massa seca total. O crescimento das mudas de Petunia x hybridae G. globosa modificou-se conforme as características dos substratos e as épocas de cultivo. O substrato composto com 80% de substrato comercial e 20% de esterco bovino apresentou resultados semelhantes ou superiores ao substrato comercial, podendo ser utilizado a fim de reduzir os custos de produção sem prejuízos ao crescimento das mudas. O cultivo de Petunia x hybridaem abril resultou em mudas com maior altura, comprimento das folhas e maior acúmulo de fitomassa. As mudas de G. globosa apresentaram maior desenvolvimento da parte aérea e do sistema radicular, além de maior acúmulo de fitomassa quando cultivadas em outubro.(AU)

Biochar versus hydrochar as growth media constituents for ornamental plant cultivation

Biochar and hydrochar have been proposed as novel materials for providing soilless growth media. However, much more knowledge is required before reliable advice can be given on the use of these materials for this purpose. Depending on the material and the technology applied (pyrolysis or hydrothermal carbonization), phytotoxicity and greenhouse gas emissions have been found for certain chars. In this study, our aim was to assess the feasibility of three chars as substrate constituents. We compared two biochars, one from forest waste and the other from olive mill waste, and a hydrochar from forest waste. We studied how chars affected substrate characteristics, plant performance, water economy and respiratory CO2 emission. Substrates containing biochar from forest waste showed the best characteristics, with good air/water relationships and adequate electrical conductivity. Those with biochar from olive mill waste were highly saline and, consequently, low quality. The substrates with hydrochar retained too much water and were poorly aerated, presenting high CO2 concentrations due to high respiratory activity. Plants performed well only when grown in substrates containing a maximum of 25 % biochar from forest waste or hydrochar. After analyzing the char characteristics, we concluded that biochar from forest waste could be safely used as a substrate constituent and is environmentally friendly when applied due to its low salinity and low CO2 emission. However, biochar from olive mill waste and hydrochar need to be improved before they can be used as substrate constituents.(AU)

Biochar versus hydrochar as growth media constituents for ornamental plant cultivation

ABSTRACT Biochar and hydrochar have been proposed as novel materials for providing soilless growth media. However, much more knowledge is required before reliable advice can be given on the use of these materials for this purpose. Depending on the material and the technology applied (pyrolysis or hydrothermal carbonization), phytotoxicity and greenhouse gas emissions have been found for certain chars. In this study, our aim was to assess the feasibility of three chars as substrate constituents. We compared two biochars, one from forest waste and the other from olive mill waste, and a hydrochar from forest waste. We studied how chars affected substrate characteristics, plant performance, water economy and respiratory CO2 emission. Substrates containing biochar from forest waste showed the best characteristics, with good air/water relationships and adequate electrical conductivity. Those with biochar from olive mill waste were highly saline and, consequently, low quality. The substrates with hydrochar retained too much water and were poorly aerated, presenting high CO2 concentrations due to high respiratory activity. Plants performed well only when grown in substrates containing a maximum of 25 % biochar from forest waste or hydrochar. After analyzing the char characteristics, we concluded that biochar from forest waste could be safely used as a substrate constituent and is environmentally friendly when applied due to its low salinity and low CO2 emission. However, biochar from olive mill waste and hydrochar need to be improved before they can be used as substrate constituents.

Biochar versus hydrochar as growth media constituents for ornamental plant cultivation

ABSTRACT Biochar and hydrochar have been proposed as novel materials for providing soilless growth media. However, much more knowledge is required before reliable advice can be given on the use of these materials for this purpose. Depending on the material and the technology applied (pyrolysis or hydrothermal carbonization), phytotoxicity and greenhouse gas emissions have been found for certain chars. In this study, our aim was to assess the feasibility of three chars as substrate constituents. We compared two biochars, one from forest waste and the other from olive mill waste, and a hydrochar from forest waste. We studied how chars affected substrate characteristics, plant performance, water economy and respiratory CO2 emission. Substrates containing biochar from forest waste showed the best characteristics, with good air/water relationships and adequate electrical conductivity. Those with biochar from olive mill waste were highly saline and, consequently, low quality. The substrates with hydrochar retained too much water and were poorly aerated, presenting high CO2 concentrations due to high respiratory activity. Plants performed well only when grown in substrates containing a maximum of 25 % biochar from forest waste or hydrochar. After analyzing the char characteristics, we concluded that biochar from forest waste could be safely used as a substrate constituent and is environmentally friendly when applied due to its low salinity and low CO2 emission. However, biochar from olive mill waste and hydrochar need to be improved before they can be used as substrate constituents.