title: Chlorophyllafluorescence, under half of the adaptive growth-irradiance, for high-throughput sensing of leaf-water deficit inArabidopsis thalianaaccessions.
abstract: BACKGROUND
  Non-invasive and high-throughput monitoring of drought in plants from its initiation to visible symptoms is essential to quest drought tolerant varieties. Among the existing methods, chlorophyllafluorescence (ChlF) imaging has the potential to probe systematic changes in photosynthetic reactions; however, prerequisite of dark-adaptation limits its use for high-throughput screening.
  
  
  RESULTS
  To improve the throughput monitoring of plants, we have exploited their light-adaptive strategy, and investigated possibilities of measuring ChlF transients under low ambient irradiance. We found that the ChlF transients and associated parameters of two contrastingArabidopsis thalianaaccessions, Rsch and Co, give almost similar information, when measured either after ~20 min dark-adaptation or in the presence ofhalf of the adaptive growth-irradiance.The fluorescence parameters,effective quantum yield of PSII photochemistry(ΦPSII) andfluorescence decrease ratio(RFD) resulting from this approach enabled us to differentiate accessions that is often not possible by well-established dark-adapted fluorescence parametermaximum quantum efficiency of PSII photochemistry(FV/FM). Further, we screened ChlF transients in rosettes of well-watered and drought-stressed sixA. thalianaaccessions, underhalf of the adaptive growth-irradiance, without any prior dark-adaptation. Relative water content (RWC) in leaves was also assayed and compared to the ChlF parameters. As expected, the RWC was significantly different in drought-stressed from that in well-watered plants in all the six investigated accessions on day-10 of induced drought; the maximum reduction in the RWC was obtained for Rsch (16%), whereas the minimum reduction was for Co (~7%). Drought induced changes were reflected in several features of ChlF transients; combinatorial images obtained from pattern recognition algorithms, trained on pixels of image sequence, improved the contrast among drought-stressed accessions, and the derived images were well-correlated with their RWC.
  
  
  CONCLUSIONS
  We demonstrate here that ChlF transients and associated parameters measured even in the presence of low ambient irradiance preserved its features comparable to that of measured after dark-adaptation and discriminated the accessions having differential geographical origin; further, in combination with combinatorial image analysis tools, these data may be readily employed for early sensing and mapping effects of drought on plant's physiology via easy and fully non-invasive means.
authors.affiliation: Global Change Research Institute, The Czech Academy of Sciences, v. v. i, Bělidla 986/4a, 603 00 Brno, Czech Republic.
authors.forename: Kumud B
authors.initials: KB
authors.lastname: Mishra
authors.affiliation: Global Change Research Institute, The Czech Academy of Sciences, v. v. i, Bělidla 986/4a, 603 00 Brno, Czech Republic.
authors.forename: Anamika
authors.initials: A
authors.lastname: Mishra
authors.affiliation: Global Change Research Institute, The Czech Academy of Sciences, v. v. i, Bělidla 986/4a, 603 00 Brno, Czech Republic.
authors.forename: Kateřina
authors.initials: K
authors.lastname: Novotná
authors.affiliation: Global Change Research Institute, The Czech Academy of Sciences, v. v. i, Bělidla 986/4a, 603 00 Brno, Czech Republic.
authors.forename: Barbora
authors.initials: B
authors.lastname: Rapantová
authors.affiliation: Global Change Research Institute, The Czech Academy of Sciences, v. v. i, Bělidla 986/4a, 603 00 Brno, Czech Republic.
authors.forename: Petra
authors.initials: P
authors.lastname: Hodaňová
authors.affiliation: Global Change Research Institute, The Czech Academy of Sciences, v. v. i, Bělidla 986/4a, 603 00 Brno, Czech Republic.
authors.forename: Otmar
authors.initials: O
authors.lastname: Urban
authors.affiliation: Global Change Research Institute, The Czech Academy of Sciences, v. v. i, Bělidla 986/4a, 603 00 Brno, Czech Republic.
authors.forename: Karel
authors.initials: K
authors.lastname: Klem
keywords: Chlorophyll fluorescence transients; Drought; Natural accessions; Non-invasive methods; Plant phenotyping; Whole plant rosettes