Table 2.

Effects of different carotenoid biosynthetic genes on carotenoid composition and content as well as plastid morphology.

Common name	Organ/tissue	Gene	Approach	Effects on carotenoids	Effects on plastids	Reference
Tomato	Leaf	GGPPS	CRISPR-cas9	Decrease: β-carotene	similar number and size of chloroplasts in guard cell; smaller chloroplasts in mesophyll cells	(Barja et al., 2021)
Tomato	Fruit	GGPPS	CRISPR-cas9	Decrease: phytoene, lycopene and total carotenoids	NA
Tomato	Fruit	PSY1	Over-expression	Increase: phytoene, lycopene, β-carotene, lutein and total carotenoids	absence of distinct thylakoid membranes in mature green fruit	(Fraser et al., 2007)
Tomato	Fruit	PSY1	Mutation	Decrease: phytoene, lycopene, β-carotene and lutein	NA	(Gady et al., 2012)
Oncidium hybrid orchid	Leaf	PSY	RNA-i	Decrease: lycopene and lutein	decreased number of plastids in leaves; containing barely any grana, no starch grains and oil droplets, and little thylakoid lamellar structures	(Liu et al., 2014)
Tomato	Fruit	PDS	Over-expression	Decrease: phytoene Increase: ζ-carotene, lycopene, β-carotene	NA	(McQuinn et al., 2018)
Arabidopsis	Leaf	PDS3	Mutation	Decrease: lutein and β-carotene Increase: phytoene	no mature plastids and no thylakoid membrane system; lost ability to develop into mature chloroplasts	(Qin et al., 2007)
Tomato	Fruit	ZISO	VIGS	Decrease: ζ-carotene, lycopene and β-carotene Increase: phytoene and lutein	NA	(Fantini et al., 2013)
Watermelon	Fruit	ZISO	Mutation	Decrease: lycopene and β-carotene	NA	(Zhang J. et al., 2022)
Arabidopsis	Leaf	ZISO	Mutation	Increase: phytoene	Reduced number of carotenoid globules	(Cazzonelli et al., 2020)
Tomato	Leaf/fruit	ZDS	RNA-i	Decrease: lycopene, β-carotene and total carotenoids Increase: phytoene	disrupted thylakoid membrane structure in the leaf; green-white plastid structures in fruit	(Babu et al., 2020)
Tomato	Fruit	ZDS	Over-expression	Decrease: lycopene, β-carotene and lutein Increase: phytoene and ζ-carotene	NA	(McQuinn et al., 2020)
Arabidopsis	Leaf	CRTISO	Mutation	Decrease: lutein Increase: violaxanthin	lack of prolamellar bodies in etioplasts; less prothylakoid membranes	(Park et al., 2002)
Tomato	Fruit	CRTISO	Mutation	Decrease: lycopene, β-carotene and total carotenoids Increase: phytoene and ζ-carotene	NA	(Isaacson et al., 2002)
Sweet potato	Storage roots	LCYB2	Over-expression	Increase: β-carotene, lutein and total carotenoid	large numbers of carotenoid globules	(Chen et al., 2018a)