Table 1.

Published HD-Zip IV genes and their characteristics.

Plant	Gene name	Accession	Tissue localisation	Suggested function*	Cited
Arabidopsis thaliana	HDG1	NP_191674	In trichomes at the base of young leaf, endodermal cell lines around emergent lateral root, stamen filament	Cuticle development	[24,29]
Arabidopsis thaliana	HDG2	NP_172015	Outer cell layers of shoot apical meristems, early flower primordia, nucellus, seed coat, epidermal layers of young leaves, hairless cell files of hypocotyl epidermis, primary root tips	Embryo development	[24]
Arabidopsis thaliana	HDG3	NP_180796	Siliques and seedlings	Cotyledon development	[24]
Arabidopsis thaliana	HDG4	NP_193506	Flowers	Flower organ development	[24]
Arabidopsis thaliana	HDG5	NP_199499	All plant organs except root, outer cell layers of shoot apical meristems, early flower primordia, nucellus, epidermis of the stamen filament, stomatal guard cells of the carpel	Not determined	[24]
Arabidopsis thaliana	FWA/HDG6	NP_567722	Endosperm	Endosperm development	[30]
Arabidopsis thaliana	HDG7	NP_200030	Base of leaf primordia, apical region of the heart-stage embryo, lateral root primordia and tips, seedlings	Not determined	[24]
Arabidopsis thaliana	HDG8	NP_186976	Endosperm and embryo at early stages of development, after flower organ development	Flower, seed development	[24]
Arabidopsis thaliana	HDG9	NP_197234	Developed flowers, chalazal, embryo sac	Embryonic development	[24]
Arabidopsis thaliana	HDG12	NP_564041	Apical meristem, stamen filament, nucellus, embryo, young epidermal tissues, lateral root tip	Trichome development	[24]
Arabidopsis thaliana	GL2	NP_565223	Epidermis of leaves and roots, developing trichomes and surrounding epidermal cells, hairless cell files of hypocotyl epidermis	Trichome and root hair development	[31]
Arabidopsis thaliana	ANL2	NP_567183	Leaves, stems, buds, roots	Anthocyanin distribution and root development	[32]
Arabidopsis thaliana	ATML1	NP_193906	Flower bud, lower parts of siliques	Shoot epidermal cell differentiation	[33]
Arabidopsis thaliana	PDF2	NP_567274	Flower buds, shoot apices	Shoot epidermal cell differentiation, cotyledon development	[33]
Picea abies	PaHB1	AAG43405	Embryo	Embryo development	[34]
Picea abies	PaHB2	AAL83725	Embryo	Embryo development	[35]
Gossypium spp.	GaHOX1	ABY41242	Fibre cells	Cotton fibre development	[36]
Gossypium spp.	GaHOX2	ABY67263	Fibre cells at early developmental stages	Seed coat development	[36]
Gossypium hirsutum	GhHD-1A	AFO11041	Epidermal cells	Epidermal cell determination	[37]
Gossypium hirsutum	GhHD-1D	AFO11042	Epidermal cells	Epidermal cell determination	[37]
Zea mays	ZmOCL1	CAG38614	Immature ears, epidermis specific expression in embryo, meristems, young organ primordia, juvenile leaves	Kernel development, cuticle deposition	[7]
Zea mays	ZmOCL2	CAB96422	Apical meristem, sub-epidermal layer of floral meristems immature ears, young female gametophyte, kernels, root	Not determined	[38]
Zea mays	ZmOCL3	CAB96423	Developing embryo and endosperm, epidermis specific expression in embryo, meristems, young organ primordial, juvenile leaves	Specification of organ identity	[38]
Zea mays	ZmOCL4	CAB96424.2	Shoot epidermis, meristems and young organ primordia, immature tassels	Anther and trichome development	[39]
Zea mays	ZmOCL5	CAB96425	Immature tassels, epidermis specific expression in embryo, meristems, young organ primordia,	Not determined	[40]
Zea mays	ZmOCL6	DAA34955	Immature tassels, immature ears, epidermal cells of juvenile leaves	Not determined	[40]
Zea mays	ZmOCL7	DAA34956	Immature ears, epidermal cells	Not determined	[40]
Zea mays	ZmOCL8	DAA34957	Immature tassels, epidermal cells	Not determined	[40]
Zea mays	ZmOCL9	DAA34958	Young developing kernels, L2 cells of shoot apical meristem	Not determined	[40]
Zea mays	ZmOCL10	DAA34959	Immature tassels, epidermal layer of juvenile leaves	Not determined	[40]
Zea mays	ZmOCL11	DAA34960	Mature tassels that include pollen	Not determined	[40]
Zea mays	ZmOCL12	DAA34961	Not determined	Not determined	[40]
Zea mays	ZmOCL13	DAA34962	Immature tassels, epidermis of shoot apical meristem	Not determined	[40]
Zea mays	ZmOCL14	DAA34963	Immature tassels, epidermal cells	Not determined	[40]
Zea mays	ZmOCL15	DAA34964	Immature tassels, epidermis of shoot apical meristem	Not determined	[40]
Zea mays	ZmOCL16	DAA34965	Young developing kernels, epidermal cells	Not determined	[40]
Zea mays	ZmOCL17	DAA34966	Immature tassels, epidermis of shoot apical meristem	Not determined	[40]
Oryza sativa	OsRoc1	BAB85750	Shoot apex, inflorescence apex, leaf blade	Embryogenesis	[41]
Oryza sativa	OsRoc2	BAC77155	Shoot apex, inflorescence apex, leaf blade	Not determined	[42]
Oryza sativa	OsRoc3	BAC77156	Shoot apex, inflorescence	Not determined	[42]
Oryza sativa	OsRoc4	BAC77157	Roots	Not determined	[42]
Oryza sativa	OsRoc5	BAC77158	Leaf epidermis	Epidermal differentiation, bulliform cells development	[42]
Oryza sativa	OsROC6	Q7Y0V7	Not determined		[42]
Oryza sativa	OsRoc7	BAC77160	Epidermis	Epidermal differentiation	[42]
Oryza sativa	OsRoc8	BAC77161	Epidermis	Epidermal differentiation	[42]
Oryza sativa	OsRoc9	BAC77162	Epidermis	Epidermal differentiation	[42]
Oryza sativa	OsTF1	Q5ZAY0	Grain	Embryogenesis	[43]
Oryza sativa	OsHOX9	A2Z8L4	Not determined		[44]
Triticum aestivum	TaGL9	AEI99592	Grain specific expression	Not determined	[45]
Triticum durum	TdGL9H	AEI99593	Early embryo, endosperm around embryo, later in scutellar vascular bundle	Maintenance of scutellar vascular bundle	[45]
Solanum lycopersicum	SlCD2	NP_001234657	Epidermal cell and cuticle	Epidermal cell and cuticle development	[20]
Physcomitrella patens	PpHDZ41	DAA05775	Not determined	Not determined	[46]
Selaginella moellendorffii	SmHDZ44	DAA05774	Not determined	Not determined	[46]

^*It should be taken in consideration that the current data on HD-Zip IV function are dependent on the available data, and thus in some instances function of HD-Zip IV TFs could be speculative.