Abstract
The effects of jasmonic acid (JA) and methyl jasmonate (Me-JA) on photosynthetic efficiency and expression of some photosystem (PSII) related in different cultivars of
Brassica oleracea
L. (var.
italica, capitata
, and
botrytis
) were investigated. Plants raised from seeds subjected to a pre-sowing soaking treatment of varying concentrations of JA and Me-JA showed enhanced photosynthetic efficiency in terms of qP and chlorophyll fluorescence. Maximum quantum efficiency of PSII (
F
v/
F
m) was increased over that in the control seedlings. This enhancement was more pronounced in the Me-JA-treated seedlings compared to that in JA-treated ones. The expression of PSII genes was differentially regulated among the three varieties of
B. oleracea
. The gene
PsbI
up-upregulated in var.
botrytis
after treatment of JA and Me-JA, whereas
PsbL
up-regulated in
capitata
and
botrytis
after supplementation of JA. The gene
PsbM
showed many fold enhancements in these expressions in
italica
and
botrytis
after treatment with JA. However, the expression of the gene
PsbM
increased by both JA and Me-JA treatments.
PsbTc(p)
and
PsbTc(n)
were also found to be differentially expressed which revealed specificity with the variety chosen as well as JA or Me-JA treatments. The RuBP carboxylase activity remained unaffected by either JA or Me-JA supplementation in all three varieties of
B. oleracea
L. The data suggest that exogenous application of JA and Me-JA to seeds before germination could influence the assembly, stability, and repair of PS II in the three varieties of
B. oleracea
examined. Furthermore, this improvement in the PS II machinery enhanced the photosynthetic efficiency of the system and improved the photosynthetic productivity in terms of saccharides accumulation.