RESUMO
High throughput screening of citrus samples containing elevated concentrations of total carotenoids, flavonoids, and phenolic compounds was accomplished using ultraviolet-visible spectroscopy and Fourier transform infrared (FT-IR) spectroscopy, combined with multivariate analysis. Principal component analysis and partial least squares discriminant analysis using FT-IR spectra were able to differentiate seven citrus fruit groups into three distinct clusters corresponding to their taxonomic relationship. Quantitative prediction modeling of total carotenoids, flavonoids, and phenolic compounds in citrus fruit was established using a partial least squares regression algorithm from the FT-IR spectra. The regression coefficients (R 2) of predicted and estimated values of total carotenoids, flavonoids, and phenolic compounds were all 0.99. The results indicated that accurate quantitative predictions of total carotenoids, flavonoids, and phenolic compounds were possible from citrus fruit FT-IR spectra, and that the resulting quantitative prediction model might be useful as a rapid selection tool for citrus fruits containing elevated carotenoids, flavonoids, and phenolic compounds.
RESUMO
We determined the effects of atmospheric temperature (10-30 ± 2°C in 5°C increments) and carbon dioxide (CO2) levels (400 ± 50 ppm, 540 ± 50 ppm, and 940 ± 50 ppm) on the infection of Solanum tuberosum cv. Chubaek by Potato leafroll virus (PLRV). Below CO2 levels of 400 ± 50 ppm, the PLRV infection rate and RNA content in plant tissues increased as the temperature increased to 20 ± 2°C, but declined at higher temperatures. At high CO2 levels (940 ± 50 ppm), more plants were infected by PLRV at 30 ± 2°C than at 20 or 25 ± 2°C, whereas PLRV RNA content was unchanged in the 20-30 ± 2°C temperature range. The effects of atmospheric CO2 concentration on the acquisition of PLRV by Myzus persicae and accumulation of PLRV RNA in plant tissues were investigated using a growth chamber at 20 ± 2°C. The M. persicae PLRV RNA content slightly increased at elevated CO2 levels (940 ± 50 ppm), but this increase was not statistically significant. Transmission rates of PLRV by Physalis floridana increased as CO2 concentration increased. More PLRV RNA accumulated in potato plants maintained at 540 or 940 ± 50 ppm CO2, than in plants maintained at 400 ± 50 ppm. This is the first evidence of greater PLRV RNA accumulation and larger numbers of S. tuberosum plants infected by PLRV under conditions of combined high CO2 levels (940 ± 50 ppm) and high temperature (30 ± 2°C).
RESUMO
[This corrects the article on p. 321 in vol. 32, PMID: 27493607.].
RESUMO
We examined the effects of temperature on acquisition of Potato virus Y-O (PVY-O), Potato virus A (PVA), and Potato leafroll virus (PLRV) by Myzus persicae by performing transmission tests with aphids that acquired each virus at different temperatures. Infection by PVY-O/PVA and PLRV increased with increasing plant temperature in Nicotiana benthamiana and Physalis floridana, respectively, after being transmitted by aphids that acquired them within a temperature range of 10-20°C. However, infection rates subsequently decreased. Direct qRT-PCR of RNA extracted from a single aphid showed that PLRV infection increased in the 10-20°C range, but this trend also declined shortly thereafter. We examined the effect of temperature on establishment of virus infection. The greatest number of plants became infected when N. benthamiana was held at 20°C after inoculation with PVY-O or PVA. The largest number of P. floridana plants became infected with PLRV when the plants were maintained at 25°C. PLRV levels were highest in P. floridana kept at 20-25°C. These results indicate that the optimum temperatures for proliferation of PVY-O/PVA and PLRV differed. Western blot analysis showed that accumulations of PVY-O and PVA coat proteins (CPs) were lower at 10°C or 15°C than at 20°C during early infection. However, accumulation increased over time. At 25°C or 30°C, the CPs of both viruses accumulated during early infection but disappeared as time passed. Our results suggest that symptom attenuation and reduction of PVY-O and PVA CP accumulation at higher temperatures appear to be attributable to increased RNA silencing.
