Table 1 Biotype classification of 32E. melilotiisolates on the basis of their symbiotic profiles

Strain name^a	Symbiotic pattern^b	Ratio of E:O:I	Biotype^c	Specificity^d
QL2, WLG1	EOOOO	1:4:0	I	E1
LL11	OEOOO	1:4:0	II	E1
G3L3, LP3	OOEOO	1:4:0	III	E1
LL1	OOOEO	1:4:0	IV	E1
LL2	EEOOO	2:3:0	V	E2
WLP2	OEOEO	2:3:0	VI	E2
G9L3, G9L8	OIOEO	1:3:1	VII	E1I1
G3L2, G3L6, G3L8, G3T2, G9L4, G9L6, LL5, LL6, LL7	OOOOO	0:5:0	VIII	N
G3L4, G3L7, G3L10, G3L12, G3L13, G9L5, LL10	OIOOO	0:4:1	IX	I1
G3L9	OOOIO	0:4:1	X	I1
G3L5, LL8, QL4, QL5	OOOOI	0:4:1	XI	I1
G9L7	OOOII	0:3:2	XII	I2

^aA prefix was assigned to inform plant cultivar from which the strains was originally isolated: G3 for Gannong No. 3; G9, Gannong No. 9; L, Longzhong; Q, Qingshui; WL, WL168HQ
^bThe symbiotic pattern was obtained by combining the marked symbiotic efficiency of each strain in the order of cultivar G3, G9, L, Q and WL. Letter E (effective), O (noneffective), or I (inhibitory) indicates shoot dry weight value was significantly higher, not significantly different, or significantly lower (P< 0.05) when compared with uninoculated plants, respectively (Additional files8)
^cRoman numerals refer to rhizobial biotypes for strains determined based on the symbiotic pattern
^dE1 Effective one-cultivar specific biotype, E2 Effective two-cultivars specific biotype, E1I1 Effective one-cultivar and inhibitive one-cultivar specific biotype, N Non-specific biotype, I1 Inhibitory one-cultivar specific biotype, I2 Inhibitory two-cultivars specific biotype