Table 1.

Main features of phytocytokines in biotic stress.

Phytocytokine	Species of Origin	Signal Transduction	Induced Defense Responses and Signaling	References
Peps	Arabidopsis	PEPR1 and PEPR2	media alkalinization, H2O2 PDF1.2 and PROPEPs expression	[11]
		BAK1	Ca2+, ET, callose	[9]
		BIK1/PBL1	Ca2+, H2O2 NO MPK3 and WRKY33 expression	[18]
ZmPep1	Maize		JA, ET, defense gene expression, defense metabolites accumulation	[12]
ZmPep3	Maize		JA, ET, defense gene expression, volatiles emission, phytoalexin	[19]
PIP1	Arabidopsis	RLK7	ROS, FRK1, WRKY30, WRKY33, WRKY53, MYB51 and PR1 expression	[14]
		partially BAK1- dependent	MAPK, Callose, Stomatal closure
SCOOP12	Arabidopsis	MIK2-BAK1/SERK4	ROS, callose	[16]
			Phosphatidic acid (PA) FRK1 expression	[20]
SCOOPs		BIK1/PBL1	Ca2+, ROS, MAPK Ethylene, defense gene expression	[21]
PNP-A	Arabidopsis	PNP-R2	antagonizes SA responses, stomatal closure	[22]
RALF23	Arabidopsis	FER-BAK1	Ca2+, Media alkalinization	[23]
			Antagonizes PAMP-induced ROS
IDL6	Arabidopsis	HAE and HSL2	Poligalacturonase gene ADPG2	[24]
GRI	Arabidopsis	PRK5	ROS-dependent Cell death, hormones	[25,26]
CEP4	Arabidopsis	CEPR1/2 and RLK7	Ca2+, MAPK Ethylene, FRK1 expression	[27]
Systemin	Tomato	SYR1	Opening of ion channels, Ca2+, MAPKs JA, defense genes	[10]
		SYR2	CDPKs, ROS Protease inhibitors	[28]
		PORK1	CAT and APX activity Volatiles emission	[29]
PotSys1 and 2	Potato	SYR1 and SYR2	Proteinase inhibitors	[30]
PepSys	Pepper
NishSys	Nightshade
HypSys1, 2 and 3	Tomato		Media alkalinization JA, PI-I, and PI-II	[31]
	Potato		H2O2 PIs, JA, defense-related genes, antioxidant defensive enzymes	[32]
TobHypSys 1 and 2	tobacco		Media alkalinization, MAPK Proteinase inhibitors	[33]
CAPE1	Tomato		H2O2 SA, defense gene expression	[15]
PSK	Arabidopsis	PSRKs	Ca2+ IAA and Auxin-dependent responses	[34]
	Tomato			[35]
PSY1	Arabidopsis	PSY1R		[34]
SubPep	Soybean		Media alkalinization Chitinase1b, CYP93A1, chalcone synthase and PDR12 gene expression	[36]
Pep914	Soybean		Media alkalinization CYP93A1, Chib1-1, and chalcone synthase gene expression	[13]
Pep890
Zip1	Maize		SA, SA, and JA marker genes, defense-related genes	[37]
SAMP	Citrus		Defense gene expression	[17]