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Arabidopsis thaliana as a model plant, is always a species of choice for testing the newest technology application. Cold tolerance as a result of cold acclimation was measured by using a non-invasive method (ChlF). Nine Arabidopsis thaliana accessions (Cvi, Can, C24, Co, Col-0, Nd, Ler, Rsch and Te) were measured for cold sensitivity and tolerance. Six week intact whole plant seedlings were treated by 3 types of treatments: non-acclimated; cold acclimated 4°C for two weeks; sub-zero temperature treated -4°C for 8 h in the dark. A combined image and statistics analysis 3 replications showed that the ChlF parameter: maximum quantum yield of PSII photosystems (Fv / Fm) and fluorescence decrease ratio (RFD) had some significant

differences. For the cold sensitive accessions (Co, C24, Can and Cvi), ChlF transients were basically consistent across the 3 conditions. For intermediate cold tolerant accessions (Ler and Nd) and cold tolerant accessions (Col, Rsch and Te), ChlF emission had significant changes. Effective quantum efficiency of PSII photochemistry (ФPSII) was significantly higher in cold acclimated vs. non-acclimated except for Cvi. Combining images analysis, the different cold sensitivity of the nine species was well discriminated and characterized. This experiment indicated that ChlF is a valuable method for high-throughput detection of cold tolerance of whole plants (Mishra, Heyer & Mishra 2014).

In cereal crop studies, different types of important crops have been used for high throughput screening with chlorophyll fluorescence imaging ChlF parameters and visual imaging for large scale detection of traits and marker assisted selection breeding. This is a powerful technique as advanced phenotyping parameters have been widely used on crop species for speeding up breeding progress. Especially for some complex traits, such as photosynthesis, variants are more easily detected for cloning by using high-throughput screening (HTPS) of phenotypes and genotypes. Moreover, HTPS can replace traditional labor and cost intensive work. Except for initially preparing the available population for testing, harvesting accurate phenotypic information is always the decisive factor in successful breeding. Among the many available technologies, chlorophyll fluorescence imaging (CFI) technology is an optical, rapid, non-contact, non-destructive and repeatable method that can be used in any growth stage of the plant allowing the physiological state of plants to be measured with different treatment responses (Harbinson et al. 2012). Combining this with genotype data, linkage mapping and association mapping can be used to detect QTLs locations on crop chromosomes.

40 Photosynthesis has an essential function on plant yield research and it has an important significance in crop genetics and breeding for improved productivity with reduced inputs in the future (Flood, Harbinson & Aarts 2011). CFI offers an option to analyse a number of steps of the photosynthetic process. With present technology about 103 plants can be measured several times per day just by one camera. The huge amount of image management required to deal with this data requires advanced image software and better physiological models for analyzing (Harbinson et al. 2012).

In a winter and spring oats frost damage study, ChlF was used to evaluate the cold acclimation and freezing damage. 12 winter and 3 spring oats (Avena sativa L.,) were used as experimental materials and were cold acclimated and treated with freezing treatments. A dominant reversible decrease in Fv / Fm was found in all genotypes during

acclimation to low, non-freezing temperatures, which is a rapid and effective method to detect crop low temperature tolerance. It has been identified ChlF is a more sensitive and precise method than others and is highly correlated with field-evaluated frost damage (Rizza et al. 2001). Crown rust (Puccinia coronata) infected oat leaves give rise to heterogeneous changes in photosynthesis as identified by quantitative imaging of chlorophyll fluorescence (Scholes & Rolfe 1996). Moreover, salinity tolerance physiological responses also can be detected by ChlF method (Zhao, Ma & Ren 2007). Cold acclimation and freezing tolerance of winter and spring oats (Avena sativa L.) were rapid evaluated and measured by Fv / Fm (Herzog & Olszewski 1998).

In wheat studies, nitrogen deficiency and water deficit strongly reduced the photosynthetic activity. ChlF parameter Fv / Fm showed that the affect is more

significant from the low-N than the high-N treatment. Nitrogen deficiency leads to reduction of the total ChlF content and increases the Chl a/b ratio (Shangguan, Shao & Dyckmans 2000). Grain yield is one of the important selection criterion for durum wheat (Triticum durum Desf.). The ChlF measurement method showed that the growing environment has a strong influence on yield and all the fluorescence parameters (Araus et al. 1998). In a doubled haploid population of 94 lines from the wheat cross Chinese Spring × SQ1, 116 Quantitative trait loci with ChlF parameters were located on all chromosomes except 7B; 39 and 3 QTLs were identified for pigments and plant productivity traits which were mapped separately. 14 chlorophyll content and grain weight per ear QTLs were detected on chromosome 6B. All of that will provide key traits genetics information for future breeding (Czyczyło-Mysza et al. 2013). Moreover, 37 heat tolerance QTLs were also located by ChlF kinetics parameters and 5 QTLs

41 regions significantly associated with response to heat stress of wheat were identified (Azam, Chang & Jing 2015; Talukder et al. 2014).

In maize studies, ChlF parameters have been be used to evaluate differential heavy metal toxicity of maize plants at differential stages (Adam & Murthy 2014; Da Silva et al. 2012; Gouveia-Neto et al. 2012; Marques & do Nascimento 2013). Cold stress is a key environmental factor, the changes in ChlF signals have help detect, improve and understand cold induced response mechanisms in maize studies (Rodríguez et al. 2014; Rodríguez et al. 2013). Effects of nitrogen fertilization of maize were also be measured by ChlF parameters for improving N utilization and gas exchange (Akram et al. 2011; Wu et al. 2013). QTLs genetic analysis was also applied in maize genetics breeding in field environments using morphological traits (Cai et al. 2012; Šimić et al. 2014). Under water-limited or drought condition, photosynthetic performance was detected by ChlF for comparing differential maize inbred lines (Lepeduš et al. 2012; Liu et al. 2012). In addition, cold related QTLs genetics loci were found (Rodríguez et al. 2014). Changes in fluorescence kinetics were used also for testing the effects of high temperature in maize (Xu et al. 2011).

In rice research, photochemical properties of flag leaves of different rice species were detected by ChlF transients (Zhang et al. 2015). Fv / Fm was also used to evaluate

somaclonal variations related to improved chilling tolerance in rice (Bertin, Bouharmont & Kinet 1997). Non-photochemical quenching (NPQ) capacity, with regulates energy conversion in photosystem II and protects plants from photoinhibition was induced by medium and high light intensities or osmotic stress in rice leaves of rice cultivars (Kasajima et al. 2011; Li et al. 2015). The dynamic change of

microelement/microelement and ChlF were used to determine photosynthetic system

changes and the changes in grain for improving rice quality (Shrestha, Brueck & Asch 2012; Zhang et al. 2014). In a field environment, ChlF provides reference data for field growth and yield management, such as flooding/waterlogging stress, field day and night temperature, heat and drought stress and toxicity etc. (Gu et al. 2014; He et al. 2013; Kumar, Vijayalakshmi & Vijayalakshmi 2014; Šebela et al. 2015).

2.2 Transcriptome and Gene Expression Profile