Genome-wide expression of low temperature response genes in Rosa hybrida L.

Plants respond to low temperature stress during cold acclimation, a complex process involving changes in physiological and biochemical modifications. The rose serves as a good model to investigate low temperature responses in perennial ornamentals. In this study, a heterologous apple microarray is used to investigate genome-wide expression profiles in Rosa hybrida subjected to low temperature dark treatment. Transcriptome profiles are determined in floral buds at 0h, 2h, and 12h of low temperature treatment (4 °C). It is observed that a total of 134 transcripts are up-regulated and 169 transcripts are down-regulated in response to low temperature. Interestingly, a total of eight up-regulated genes, including those coding for two cytochrome P450 proteins, two ankyrin repeat family proteins, two metal ion binding proteins, and two zinc finger protein-related transcription factors, along with a single down-regulated gene, coding for a dynamin-like protein, are detected. Transcript profiles of 12 genes known to be involved in cold stress response are also validated using qRT-PCR. Furthermore, expression patterns of the AP2/ERF gene family of transcription factors are investigated in both floral buds and leaves. Overall, AP2/ERFs genes are more rapidly induced in leaves than in floral buds. Moreover, differential expression of several AP2/ERF genes are detected earlier in vegetative rather than in reproductive tissues. These findings highlight important roles of various low temperature response genes in mediating cold acclimation, thereby allowing roses to adapt to low temperatures, but without adversely affecting flower bud development and subsequent flowering, while vegetative tissues undergo early adaptation to low temperatures.

Relação entre medidas de refletância e área foliar sadia, severidade da ferrugem asiática e produtividade da cultura da soja / Relationships between measures of reflectance and health leaf area, soybean rust severity and soybean yield

O objetivo do trabalho foi verificar se as medidas de refletância detectavam variações na área foliar sadia a fim de serem utilizadas como parâmetros para estimar danos na produção decorrentes da ferrugem asiática, bem como determinar a influência da doença na eficiência fotossintética das plantas em condições de campo. O experimento foi conduzido na área experimental pertencente à Embrapa Soja, no município de Londrina, PR, utilizou-se a cultivar de soja BRS 154. O delineamento experimental utilizado foi de blocos ao acaso, com oito tratamentos (diferentes estádios de início da aplicação do fungicida) comquatro repetições O produto utilizado foi azoxistrobin + ciproconazole (60+24 g i.a./ha) + óleo mineral (0,5%). As leituras de refletância foram feitas em oito comprimentos de onda, de 460 a 810 nm, em intervalos de 50 nm. Calculou-se o Índice Vegetativo de Diferença Normalizada (NDVI), onde NDVI=(810- 660)/(810+660). A produção apresentou incremento linear (P<0,01) com a Duração da Área Foliar Sadia (HAD) (r2=37,7%), com a Absorção da Radiação Solar pela Área Foliar Sadia (HAA) (r2=21,6%), com aÁrea Abaixo da Curva de Progresso da Doença (AUDPC) (r2=25,4%) e com a Integral da Diferença Normalizada (AURNDVI) (r2=54,8%). Verificou-se diferença significativa (P<0,05) na Eficiência Fotossintética (RUE) entre a testemunha e o tratamento que recebeu três aplicações de fungicida (primeira em R4), sendo esse também o único tratamento que diferiu significativamente (P<0,05) da testemunha em produtividade. Apesar dos baixos valores para os coeficientes de determinação, a sensibilidade dasmedidas de NDVI e RUE apresentaram potencial para captar variações entre os tratamentos. Sugerem-se novos estudos para verificar e eliminar possíveis interferências decorrentes da calibração do radiômetro e dos demais parâmetros antes dessas medidas poderem ser utilizadas no processo de tomada de decisão para controle da ferrugem asiática.

The aim of this research was to verify if some measures of reflectance could detect variations in the healthy leaf area which could be used as parameter to estimate damages in the production due to soybean rust, and to determine the influence of the disease on photosinthetic efficiency of plants underfield conditions. The experiment was lead in the experimental area of Embrapa, in Londrina, PR. The experimental design was randomly blocks, with eight treatments (different fungicide application times) with four replications. The fungicide used was azoxistrobin + ciproconazole (60+24 g i.a./ha) + mineral oil (0.5%). The reflectance readings were made at eight wave lengths, between 460 and 810 nm, with intervals of 50 nm. It was estimated the Normalized Difference Vegetation Index (NDVI), where NDVI=(810-660)/ (810+660). The yield presented linear increments (P<0.01) with Healthy Leaf Area Duration (HAD)(r2=37.7%), with Healthy Area Absorption (HAA) (r2=21.6%), with Area Under Disease Progress Curve(AUDPC) (r2=25.4%) and with Integral of Normalized Difference (AURNDVI) (r2=54.8%). Significant difference in Photosynthetic Efficiency (RUE) (P<0.05) was observed between the control plot and the treatment with three fungicide applications (first at R4), which was the only treatment that differed significantly (P<0.05) in production from untreated control. The sensitivity of the measures NDVI andRUE presented a potential to detect variations among the treatments. However additional studies are still needed to verify and eliminate some possible interferences, such as the calibration of the radiometer and other parameters before it can be used for taking of decisions.