Table 1.

Evidence from the literature for selection of target genes to improve forage quality

Target trait	Gene	Species	Suppression mode	Effect on trait	Pleiotropic effects	Reference
Digestibility	4CL/Class I	Sorghum bicolor	Missense mutant bmr2	17 % increased saccharification		Saballos et al. (2008); Sattler et al. (2010)
		Saccharum officinarum	RNAi	52 %, 76 % improved saccharification (field-grown)	0 %, 30 % DM yield penalty (field-grown)	Jung et al. (2016)
	BAHD01	Setaria viridis, Saccharum officinarum	RNAi	40–80 % increased saccharification	No growth penalty in GH	de Souza et al. (2018, 2019)
	BAHD05	Setaria viridis	RNAi	10–20 % increased saccharification	No growth penalty in GH	Mota et al. (2021)
	COMT	Zea mays	bm3 LOF mutant	Used in commercial hybrids with improved digestibility for cattle	Some reports yield penalty, sometimes no yield penalty	Sattler et al. (2010);Vignols et al. (1995)
		Sorghum bicolor	bmr12 LOF mutant	30 % increased tract digestibility	10 % DM yield penalty	Saballos et al. (2008); Sattler et al. (2010)
		Panicum virgatum	RNAi	30 % increased digestibility	No growth penalty in GH	Fu et al. (2011a)
		Saccharum officinarum	TALEN induced LOF mutations in multiple paralogues	40 % improved saccharification (field-grown)	No DM yield penalty (field-grown)	Kannan et al. (2018)
	CAD/Group I	Brachypodium distachyon	Missense mutants	40 % increased saccharification	No growth penalty in GH	Bouvier d’Yvoire et al. (2013)
		Sorghum bicolor	Missense mutant bmr6-3	20 % increased tract digestibility	15 % DM yield penalty	(Saballos et al. (2009);Sattler et al. (2010)
		Zea mays	bm1		No yield penalty	Halpin et al. (1998); Sattler et al. (2010)
		Panicum virgatum	RNAi	20 % increased saccharification	Normal GH growth	Fu et al. (2011b)
	CCR	Zea mays	RNAi	20 % increased saccharification	Increased growth GH	Park et al. (2012)
	GT43A/IRX14	Brachypodium distachyon	Missense mutant?	10 % increased saccharification	No growth penalty in GH	Whitehead et al. (2018)
	CCoAOMT	Zea mays	Association with polymorphisms	Correlation with fibre digestibility		Brenner et al. (2010)
Lipid content	SDP1, SDP1-like	Arabidopsis	LOF mutant	Increase in leaf triacylglycerol	Poor seedling establishment in oilseeds	Kelly et al. (2013)
		Medicago truncatula	VIGS	Increase in leaf lipid content	None	Wijekoon et al. (2020)
	CGI-58	arabidopsis	LOF mutant	Increase in leaf triacylglycerol	None	James et al. (2010)
	PXA1, PXA1-like	arabidopsis	LOF mutant	Increase in leaf triacylglycerol	poor seedling establishment in oilseeds, starvation sensitive, jasmonate deficient	Slocombe et al. (2009)
		Medicago truncatula	VIGS	Increase in leaf lipid content	none	Wijekoon et al. (2020)
	TGD1	arabidopsis	Leaky mutant	Increase in leaf triacylglycerol	embryo defect, growth penalty	Xu et al. (2005)
	TGD2	arabidopsis	Leaky mutant	Increase in leaf triacylglycerol	embryo defect, growth penalty	Awai et al. (2006)
	TGD3	arabidopsis	Leaky mutant	Increase in leaf triacylglycerol	Embryo defect, growth penalty	Lu et al. (2007)