Table 2.

Functionally characterized LBD genes and their phylogenetic classification. “-” means “no reports so far”.

Classes	Species	Genes	Biological Processes	Target or Downstream Genes	References
Class IA	Arabidopsis	AtLBD25/ DDA1	Auxin signaling, photomorphogenesis	- (no reports so far)	[15]
	Arabidopsis	AtLOB/ ASL4	Leaf adaxial–abaxial polarity, floral organ development, brassinasteroid accumulation	BAS1	[2,59,60,61]
	Arabidopsis	AtLBD6/AS2	Leaf adaxial–abaxial polarity, floral organ development	BP, KNAT2	[62,63,64,65,66]
	Arabidopsis	AtLBD36/AS1
	Arabidopsis	At LBD10	Pollen development	-	[67,68,69]
	Arabidopsis	At LBD28	Leaf adaxial–abaxial polarity, SAM genesis	-	[47]
	Rice	OsLBD1-9/ OsAS2; OsIG1	Shoot differentiation, leaf development	-	[70]
			Empty-glume identity, floral organ number control, female gametophyte development	EG1, OsMADS1 and OsMADS6	[71]
	Rice	OsRAMOSA2/ OsRA2	Panicle architecture establishment	LAX1, RCN2	[54]
	Maize	ramosa2/ ra2	Inflorescence architecture establishment	-	[56]
	Maize	IG1	Embryo sac, leaf and tassel development	KN1, RS1, LG3, LG4A/B, and KNOX3	[57]
	Wheat	TaAS2	Leaf adaxial–abaxial polarity	-	[72]
	Barley	Vrs4 / HvRA2	Control lateral spikelet fertility and row-type pathway	Vrs1, HvSRA and T6P	[50]
	Apple	MdLBD11	Leaf and flower development	-	[28]
	Lotus japonicus	LjLOB1	Compound leaf development, Floral development	-	[46]
		LjLOB3
	Lotus japonicus	SLP	Pulvinus development, leaf movement	-	[16]
	Medicago	ELP1/ PLP	Pulvinus development, leaf movement	-	[16,17,18]
	Pea	APU	Pulvinus development, leaf movement	-	[16]
Class IB	Arabidopsis	AtLBD14	ABA-mediated lateral roots formation	AtHB7 and AtHB12	[51,73]
	Arabidopsis	AtLBD16	Lateral roots formation, callus formation, gall formation	FAD-BD, ARF7 and ARF19	[21,40,43,44,52,74]
	Arabidopsis	AtLBD17	Auxin-induced callus formation	-	[52,74]
	Arabidopsis	AtLBD18	Tracheary element differentiation, lateral roots formation, callus formation, auxin signaling	ARF7 and ARF19, EXP14, E2Fa, VND6 and VND7	[44,74,75,76]
	Arabidopsis	AtLBD19	Callus formation	-	[77]
	Arabidopsis	AtLBD20	Fusarium wilt susceptibility, jasmonate signaling	MYC2, Thi2.1, VSP2, and PDF1.2	[19]
	Arabidopsis	AtLBD29	Lateral roots formation, callus formation, auxin signaling	ARF7 and ARF19	[40,52,74,78]
	Arabidopsis	AtLBD30/ JLO	Tracheary element differentiation, embryogenesis, shoot, root and floral meristems development, auxin signaling	VND6 and VND7	[66,76,79,80]
	Arabidopsis	AtLBD33	Auxin-mediated lateral roots formation	ARF7 and ARF19, E2Fa	[75]
	Rice	OsDH1	Floral organ development	-	[81]
	Rice	Crownrootless1 (crl1); OsARL1	Auxin-mediated crown root formation	FSM, GTE4 and MAP	[42,82,83]
			Auxin-mediated adventitious root formation	-	[84]
	Maize	ZmLBD2/ RTCS	Embryonic seminal and post-embryonic shoot-borne root initiation, auxin signaling	ZmArf34	[5,41,85]
	Maize	ZmLBD43/ RTCL
	Lotus japonicus	LjLOB 4	Compound leaf development, Floral development	-	[46]
Class IC	Arabidopsis	AtLBD3/ ASL9	Cytokinin-responsive biological events	-	[23]
	Arabidopsis	At LBD12	Growth of abaxial leaf surface, apical dominance and fertility	-	[86]
	Arabidopsis	At LBD13	Lateral root formation	-	[49]
	Arabidopsis	At LBD15	Tracheary element development, SAM development	WUS	[48,87]
	Rice	OsLBD3-7	Leaf rolling	-	[55]
	Rice	OsLBD12-1	SAM size control	AGO10	[53]
	Eucalyptus grandis	EgLBD29	Secondary xylem formation, response to Gibberellin (GA) and indol-3-acetic acid (IAA)	-	[35]
	Eucalyptus grandis	EgLBD37	Secondary phloem formation, response to GA and IAA	-	[35]
	Citrus	CsLOB1	Citrus bacterial canker disease susceptibility	-	[20]
Class IE	Arabidopsis	At LBD27	Pollen development	-	[67,68,69]
Class II	Arabidopsis	At LBD40	GA response	-	[22]
	Arabidopsis	AtLBD41/ ASL38	Leaf adaxial-abaxial polarity	-	[88]
	Arabidopsis	At LBD37	Anthocyanin synthesis, nitrogen responses	PAP1 and PAP2	[24]
	Arabidopsis	At LBD38
	Arabidopsis	At LBD39
	Rice	OsLBD37	Nitrogen metabolism, heading date	Ehd1	[25,26]
	Rice	OsLBD38	Heading date	Ehd1	[26]
	Medicago	MtLBD1	Lateral roots emergence, auxin signaling	HB1	[58]