Methyl jasmonate changes the levels of Rubisco and other leaf proteins in Ricinus communis

The effect of methyl jasmonate (MJ) on the water-soluble protein pattern of Ricinus communis leaves was analyzed. Several dynamic changes occurred aft er a period of 24 and 48h including six proteins (M-r 13,000, 15,000, 16,00 0, 27,000, 29,000 and 60,000) whose levels increased by 48h and seven other s (M-r 11,000, 18,000, 20,000 30,000, 37,000, 40,000 and 58,000) whose leve ls decreased. Four proteins (M-r 24,000, 34,000, 64,000 and 66,000) were in duced after 24h of treatment, but returned to control levels by 48h. On the other hand, the levels of three proteins (M-r 74,000, 84,000 and 88,000) d ecreased after 24h, but returned to control levels after 48h. One of the pr oteins that accumulated after 48 h had the 13 first residues sequenced. Thi s polypeptide named MJRC-15, was identical to the C-terminal sequence of Ru bisco-large chain polypeptide (position 337-350) from tobacco chloroplast. Western-blot analysis using polyclonal antibodies against Rubisco supports the hypothesis that MJRC-15 is a degradation product of Rubisco.