Temperature and Cultivar Effects on Anthocyanin and Chlorophyll b Concentrations in Three Related Lollo Rosso Lettuce Cultivars

Abstract

<jats:p>Pigment concentrations in leaf tissue affect the visual and nutritional value-based indices of lettuce crop quality. To better discern the independent and interactive effects of temperature and cultivar on anthocyanin and chlorophyll b concentrations, three closely related Lolla Rosso lettuce cultivars (`Lotto', `Valeria', and `Impuls'), varying primarily in the number of genes controlling anthocyanin concentrations, were subjected to different air temperatures in controlled environments. Fifteen-day-old seedlings previously grown at 20 °C day/night (D/N) were transplanted into growth chambers maintained at 20 °C (D/N), 30/20 °C D/N and 30 °C D/N air temperatures. Twenty days later, leaf tissue was sampled for measures of pigment concentrations, calculated based on spectrophotometric absorbance readings taken at 530 nm (anthocyanin) and 660 nm (chlorophyll b) respectively. Although significant, the temperature × cultivar interaction resulted from differences in the magnitude (not direction) of the change in pigment concentrations among cultivars with changes in temperature. Regardless of cultivar, anthocyanin and chlorophyll b concentrations were highest, moderate and lowest after growth at 20 °C D/N, 30/20 °C D/N and 30 °C D/N respectively. Likewise, irrespective of temperature, anthocyanin and chlorophyll b concentrations followed the pattern `Impuls' (three genes) &gt; `Valeria' (two genes) &gt; `Lotto' (one gene). These data provide additional strong evidence that lettuce leaf pigment concentrations and growing temperatures are negatively related. The data also suggest that low temperatures during the dark phase may mitigate high temperature-driven reductions in lettuce leaf pigment levels.</jats:p>

Non-destructive Phenotyping of Lettuce Plants in Early Stages of Development with Optical Sensors

“…Hence, the breeders selecting for dark red color (high RAC) may consider temporarily subjecting lettuce plants to low temperatures where differences among genotypes are likely to be more pronounced (assuming that the pattern of changes in pigments is the same as in our study). These results are somewhat unexpected, because several previous studies reported that low temperatures lead to increased anthocyanin production in lettuce (Gazula et al, 2005, 2007; Boo et al, 2011; Chon et al, 2012; Becker et al, 2014a). However, when the regulation of anthocyanin biosynthesis [quantified as cyanidin-3- O -( 6 ″-malonyl)-glucoside] was compared in three cultivars, a substantial difference in their response to varying temperatures was detected.…”

“…Reduced concentrations of chlorophyll and anthocyanin have been observed in lettuce grown at supra-optimal temperatures (Gazula et al, 2005; Chon et al, 2012). These changes in the chlorophyll content are at odds with our observations that show overall increases in RCC with growing temperature ( Figures 7, 8 , and 13 ).…”

Metabolite profiling reveals temperature effects on the VOCs and flavonoids of different plant populations

“…Gene expression of PAL, chalcone isomerase and enzymes related to anthocyanin biosynthesis increased under lower temperature (Gazula et al . (). Mori et al .…”

Nutrient Content of Lettuce and its Improvement

“…Benoit et al [18] found that plastic-covered and uncovered lettuce plants contained 11.0 and 16.6 μg carotene per g fresh wt, respectively. Increasing temperatures from 20 o C to 30 o C reduced anthocyanin (cyanidin) and chlorophyll b concentrations in three red leaf lettuce cultivars [19]. Carotene levels of butterhead lettuce produced by various cultivation methods ranged from 1,360 to 3,190 μg/100 g fresh wt in soil-grown samples and from 1,810 to 2,760 μg/100 g in hydroponically grown samples [20].…”