Calorespirometry as a tool for studying temperature response in carrot (Daucus carota L.)

Abstract

Calorespirometric measurements of metabolic heat rates and CO2 emission rates of respiring tissues as functions of temperature enable rapid determination of the temperatures that plants are adapted to without growing them in different environmental temperatures. However, the correct choice of target material for measurements that enable prediction of growth temperature responses is crucial, and needs to be identified in a species‐ and trait‐specific manner. In this study, different carrot materials were tested: a primary culture system proposed as an in vitro test system for carrot yield potential, taproots of young plants, and the root meristem of actively growing plants during secondary root growth. The central root meristem is the most suitable for studying temperature response by calorespirometry for genotype comparison. Calorespirometric methods for predicting genotype‐specific temperature responses of crop plant cultivars can be used to predict productivity in environments with differing temperature conditions.

Stress-Induced Accumulation of DcAOX1 and DcAOX2a Transcripts Coincides with Critical Time Point for Structural Biomass Prediction in Carrot Primary Cultures (Daucus carota L.)

“… Fehér (2015) pointed that genetic differences for efficiency are more likely to be found during initiation. The usefulness of calorespirometry to study morphogenic responses (i.e., cell reprogramming) in in vitro cultures was first demonstrated by Kim et al (2006) and later, this system was also used by Nogales et al (2013) in D. carota cv. Rotin PCS to study temperature-dependent growth performance at 21°C and 28°C.…”

“…In order to calculate specific growth rates (i.e., structural biomass formation rate, R struct_biomass ) and efficiencies of biomass acquisition as described in Nogales et al (2013) , the respiratory metabolic heat rates and CO 2 emission rates were measured in PCS by calorespirometry, at different time points. To confirm reproducibility of the early peak for structural biomass formation reported by these authors in two PCS, we additionally performed new measurements in three PCS growing at two different incubation temperatures (21°C and 28°C).…”

“…In this paper, we expanded the number of cultures tested by Nogales et al (2013) and first demonstrate that the increase in structural biomass formation, showing an early peak during the lag phase of growth, is present in all the five primary cultures tested. We report that both carrot AOX genes, DcAOX1 , and DcAOX2a , previously demonstrated as the ones with major expression in the PCS ( Campos et al, 2009 ), showed increased levels of transcripts until the 4th day of culture and subsequent down-regulation before exponential growth starts.…”

“… Nogales et al (2013) developed calorespirometry as a new tool for breeding in a carrot in vitro PCS. This in vitro system, originated from quiescent secondary tap root phloem, was first established by Steward et al (1952) and later proposed by Arnholdt-Schmitt (1999) as a mean for carrot yield prediction.…”

“…This in vitro system, originated from quiescent secondary tap root phloem, was first established by Steward et al (1952) and later proposed by Arnholdt-Schmitt (1999) as a mean for carrot yield prediction. Calorespirometry has been shown to be useful to accurately monitor temperature dependent growth performance in terms of metabolic rates, respiratory rates, efficiency of biomass acquisition, and growth rates over 21 days of in vitro cultures ( Nogales et al, 2013 ). Those data showed a drastic increase in structural biomass formation until around the 4th day after inoculation during the lag phase of growth.…”