Table I. Requirement of MeSA and its modulating esterases and methyl transferase for induction of SAR in tobacco is dependent on light.

Six-week-old wild-type, RNAi::NtSABP2 #1-2, and RNAi::NtSAMT1 #28 plants were subjected to 1° and 2° inoculations either in the morning (9:00–9:30 am) or late afternoon (5:30–6:00 pm). SAR development was assessed by monitoring the reduction in the size of 2° TMV lesions on plants that received a 1° inoculation of TMV versus that on plants that received a 1° inoculation of HEPES buffer (Mock). The sizes of lesions are presented as means ± sd. The experiment was done at least twice with similar results. N/A, Not applicable.

	am Infection						pm Infection
Parameter	Wild Type		RNAi::NtSABP2 #1-2		RNAi::NtSAMT1 #28		Wild Type		RNAi::NSABP2 #1-2		RNAi::NtSAMT1 #28
1° Infection	Mock	TMV	Mock	TMV	Mock	TMV	Mock	TMV	Mock	TMV	Mock	TMV
2° TMV lesion size (mm ± sd)	1.58 ± 0.56	0.91 ± 0.33	1.99 ± 0.57	1.34 ± 0.53	1.67 ± 0.54	1.28 ± 0.44	1.69 ± 0.52	1.2 ± 0.56	1.66 ± 0.49	1.52 ± 0.52	1.48 ± 0.49	1.46 ± 0.48
Reduction (%) in 2° lesion size to Mock	N/A	42.8	N/A	32.8	N/A	23.2	N/A	29.1	N/A	8.4	N/A	1.3
SAR	N/A	+	N/A	+	N/A	+	N/A	+	N/A	−	N/A	−