Table 2. The disease indexes of the transgenic and non-transgenic cotton induced by Verticillium dahliae isolate V991 inoculation.

Lines	Disease index (2011)			Disease index (2012)
	(A)	(B)	(C)	(A)	(B)	(C)
C-19	23.3 ± 3.0	30.0 ± 2.0**	44.7 ± 2.5**	23.3 ± 3.2*	36.7  ± 1.2**	43.3 ± 4.5**
C-26	13.3 ± 3.0**	18.7 ± 1.2**	31.7 ± 2.0**	27.4 ± 1.1	38.6  ± 2.2**	49.2 ± 2.0**
C-27	24.3 ± 2.9	31.0 ± 2.0**	35.7 ± 2.5**	21.3 ± 1.2**	32.5  ± 0.9**	50.0 ± 3.5**
C-29	25.0 ± 2.0	32.7 ± 2.5*	37.7 ± 2.5**	28.9 ± 1.7	41.8  ± 2.7**	55.2 ± 2.6**
CK1	26.3 ± 1.5	39.7 ± 1.5	56.1 ± 1.0	29.2 ± 1.2	58.7 ± 1.7	73.4 ± 2.7
CK2	25.7 ± 1.2	41.3 ± 1.5	58.0 ± 2.0	30.3 ± 2.1	60.5  ± 1.6	72.4 ± 2.9

The transgenic cotton and W0 with two simples and one heart-shaped leaves were inoculated with VD spore suspension (5 × 10⁷) and 20 ml for each pot and scored for disease symptoms after 3 weeks. Data represent the mean ± SE (n ≥ 15); similar results were obtained from three independent experiments. CK1: the control transformed empty vector pBI121without GbRLK gene inoculated VD8; CK2: non transgenic plant W0 inoculated with VD8. The reaction of the plant towards the inoculated pathogen was rated on a scale from 0 to 4 modified from Ning et al.⁴⁹. Disease index = [∑ (Ni × i)/(N × 4)] × 100; i = 0 ~ 4, Ni = plant number of reaction i. (A) (B) and (C) represent the results 3, 4 and 5 weeks after inoculation, respectively. Disease index was calculated comparing data from CK. Significance of the phenotypic results was assessed using Student’s t tests (*P < 0.05, **P < 0.01).