. 2021 Aug 30;187(2):550–571. doi: 10.1093/plphys/kiab339

Table 2.

Summary of available fluorescent-based GECIs used in plants

Name	Version	Type	Peaks of excitation/emission (nm)	In vitro K_d for Ca^2+a	Subcellular localization	References
Cameleon	YC2.1	Ratio EYFP/ECFP	Ex 440/Em 480/530	0.8 μM/2 μM	Cytosol and nucleus	Allen et al. (1999); Miyawaki et al. (1999)
	YC3.6	Ratio cpVenus/ECFP	Ex 440/Em 480/530	250 nM	Cytosol and nucleus	Nagai et al. (2004); Mori et al. (2006)
	NES-YC3.6	Ratio cpVenus/ECFP	Ex 440/Em 480/530	250 nM	Cytosol	Krebs et al. (2012)
	NLS-YC3.6	Ratio cpVenus/ECFP	Ex 440/Em 480/530	250 nM	Nucleus	Krebs et al. (2012)
	NUP-YC3.6	Ratio cpVenus/ECFP	Ex 440/Em 480/530	250 nM	Nucleus	Costa et al. (2017)
	4mt-YC3.6	Ratio cpVenus/ECFP	Ex 440/Em 480/530	250 nM	Mitochondria	Loro et al. (2012)
	PM-YC3.6-LTI6b	Ratio cpVenus/ECFP	Ex 440/Em 480/530	250 nM	Plasma membrane	Krebs et al. (2012)
	2Bam4-YC3.6	Ratio cpVenus/ECFP	Ex 440/Em 480/530	250 nM	Chloroplasts and plastids	Loro et al. (2016)

	YC-Nano 65	Ratio cpVenus/ECFP	Ex 440/Em 480/530	65 nM	Cytosol and nucleus	Horikawa et al. (2010); Choi et al. (2014)
		Ratio cpVenus/ECFP
	SP-YC4.6-ER	Ratio cpVenus/ECFP	Ex 440/Em 480/530	58 nM/14.4 μM	Endoplasmic reticulum	Nagai et al. (2004); Iwano et al. (2009)
	2Bam4-YC4.6	Ratio cpVenus/ECFP	Ex 440/Em 480/530	58 nM/14.4 μM	Chloroplasts and plastids	Loro et al. (2016)

	4mt-D3cpv	Ratio cpVenus/ECFP	Ex 440/Em 480/530	600 nM	Mitochondria	Loro et al. (2013)
	D3cpv-KVK-SKL	Ratio cpVenus/ECFP	Ex 440/Em 480/530	600 nM	Peroxisomes	Palmer et al. (2006); Costa et al. (2010)
	TP-D3cpv	Ratio cpVenus/ECFP	Ex 440/Em 480/530	600 nM	Tonoplast	Krebs et al. (2012)

	CRT-D4ER	Ratio citrine/ECFP	Ex 440/Em 480/530	195 μM	Endoplasmic reticulum	Palmer et al. (2006); Bonza et al. (2013)

Twitch	Twitch 3	Ratio cpCit174/ECFP	Ex 440/Em 480/530	250 nM	Cytosol and nucleus	Thestrup et al. (2014); Waadt et al. (2017)
	Twitch 2B	Ratio cpVenus/mCerulean3	Ex 440/Em 480/530	200 nM	Cytosol and nucleus	Thestrup et al. (2014); Waadt et al. (2017)

CerTN-L15	CerTN-L15	Ratio citrine/cerulean	Ex 440/Em 480/530	1.2 μM	Cytosol and nucleus	Heim et al. (2007); Denninger et al. (2014)

GECOs	R-GECO1	Intensiometric mApple	Ex 561/Em 600	482 nM	Cytosol and nucleus	Zhao et al. (2011); Ngo et al. (2014); Keinath et al. (2015)
	NR-GECO1	Intensiometric mApple	Ex 561/Em 600	482 nM	Nuclear	Zhao et al. (2011); Kelner et al. (2018)
	NR-GECO1.2	Intensiometric mApple	Ex 561/Em 600	1.2 μM	Nuclear	Wu et al. (2013); Kelner et al. (2018); Leitão et al. (2019)
	CG-GECO1	Intensiometric cpGFP	Ex 488/Em 515	749 nM	Cytosol	Zhao et al. (2011); Kelner et al. (2018)
	CG-GECO1.2	Intensiometric cpGFP	Ex 405/Em 515	1.15 μM	Cytosol	Zhao et al. (2011); Kelner et al. (2018); Leitão et al. (2019)
	GEM-GECO1	Intensiometric cpGFP	Ex 405/Em 515	340 nM	Cytosol and nucleus	Zhao et al. (2011); Waadt et al. (2017)

	B-GECO1-mCherry	Ratio cpGFP/mCherry	Ex 405/561/Em 480/600	NA	Cytosol and nucleus	Waadt et al. (2017)
	G-GECO1.1-mCherry	Ratio cpGFP/mCherry	Ex 488/561/Em 515/600	NA	Cytosol and nucleus	Waadt et al. (2017)
	R-GECO1-mTurquoise	Ratio mApple/mTurqouise	Ex 405/561/Em 480/600	NA	Cytosol and nucleus	Waadt et al. (2017)

GCaMPs	GCaMP3	Intensiometric cpGFP	Ex 488/Em 515	542 nM	Cytosol and nucleus	Tian et al. (2009); Nguyen et al. (2018)
	GCaMP5	Intensiometric cpGFP	Ex 488/Em 515	NA	Cytosol and nucleus	Akerboom et al. (2012); Diao et al. (2018)
	GCaMP6f	Intensiometric cpGFP	Ex 488/Em 515	375 nM	Cytosol and nucleus	Chen et al. (2013); Waadt et al. (2017)
	GCaMP6s	Intensiometric cpGFP	Ex 488/Em 515	144 nM	Cytosol and nucleus	Liu et al. (2017); Shao et al. (2020)
	NES-GCaMP6m	Intensiometric cpGFP	Ex 488/Em 515	167 nM	Cytosol	Luo et al. (2020)
	NLS-GCaMP6m	Intensiometric cpGFP	Ex 488/Em 515	167 nM	Nucleus	Luo et al. (2020)
	ER-GCaMP6-210	Intensiometric cpGFP	Ex 488/Em 515	210 μM	Endoplasmic reticulum	de Juan-Sanz et al. (2017); Resentini et al. (2021a)
	GCaMP6f-mcherry	Ratio cpGFP/mCherry	Ex 488/561/Em 480/600	NA	Cytosol and nucleus	Waadt et al. (2017)
	MatryoshCaMP6s	Ratio cpGFP/LSSmOrange	Ex 440/Em 515/600	197 nM	Cytosol and nucleus	Ast et al. (2017)

Case	Case12	Intensiometric cpGFP	Ex 488/Em 515	1 μM	Cytosol and nucleus	Souslova et al. (2007); Zhu et al. (2013)

CEPIA	CRT1a-R-CEPIAer	Intensiometric cpGFP	Ex 561/Em 600	565 μM	Enoplasmic reticulum	Suzuki et al. (2014); Luo et al. (2020)

Aequorin	Aequorin	Bioluminescence	No Ex-/Em 465	7.2–13 μM	Cytosol and nucleus	Knight et al. (1991); Brini et al. (1995)
	Aequorin	Bioluminescence	No Ex-/Em 465	7.2–13 μM	Nucleus	van Der Luit et al. (1999)
	Aequorin	Bioluminescence	No Ex-/Em 465	7.2–13 μM	Chloroplast stroma	Johnson et al. (1995)
	Aequorin	Bioluminescence	No Ex-/Em 465	7.2–13 μM	Mitochondria	Logan and Knight (2003)
	Aequorin	Bioluminescence	No Ex-/Em 465	7.2–13 μM	Golgi	Ordenes et al. (2012)
	Aequorin	Bioluminescence	No Ex-/Em 465	7.2–13 μM	Vacuole/tonoplast	Knight et al. (1996)

YFP-aequorin	CYA	Bioluminescence	No Ex-/Em 465	7.2–13 μM	Cytosol	Mehlmer et al. (2012)
	NYA	Bioluminescence	No Ex-/Em 465	7.2–13 μM	Nucleus	Mehlmer et al. (2012)
	YA	Bioluminescence	No Ex-/Em 465	7.2–13 μM	Plasma membrane	Mehlmer et al. (2012)
	CHYA	Bioluminescence	No Ex-/Em 465	7.2–13 μM	Chloroplast/plastid stroma	Mehlmer et al. (2012); Sello et al. (2016)
	MYA	Bioluminescence	No Ex-/Em 465	7.2–13 μM	Mitochondria	Mehlmer et al. (2012)
	OEYA	Bioluminescence	No Ex-/Em 465	7.2–13 μM	Chloroplast outer envelope	Mehlmer et al. (2012); Sello et al. (2016)
	IEYA	Bioluminescence	No Ex-/Em 465	7.2–13 μM	Chloroplast inner envelope	Mehlmer et al. (2012); Sello et al. (2016)
	TL-YA	Bioluminescence	No Ex-/Em 465	7.2–13 μM	Chloroplast thylakoid lumen	Sello et al. (2018)
	TM-YA	Bioluminescence	No Ex-/Em 465	7.2–13 μM	Chloroplast thylakoid membrane	Sello et al. (2018)

GFP5-aequorin	pchitGFP5:AQ	Bioluminescence	No Ex-/Em 465	NA	Apoplast	Gao et al. (2004)

GFP-aequorin	G5A	Bioluminescence resonance energy transfer	No Ex-/Em 515	NA	Cytosol and nucleus	Baubet et al. (2000); Xiong et al. (2014)

The in vitro K_d for Ca²⁺ of the different sensors are those reported in the original works.