SINK LIMITATION INDUCES THE EXPRESSION OF MULTIPLE SOYBEAN VEGETATIVELIPOXYGENASE MESSENGER-RNAS WHILE THE ENDOGENOUS JASMONIC ACID LEVEL REMAINS LOW

The response of individual members of the lipoxygenase multigene famil y in soybeans to sink deprivation was analyzed. RNase protection assay s indicated that a novel vegetative lipoxygenase gene, vlxC, and three other vegetative lipoxygenase mRNAs accumulated in mature leaves in r esponse to a variety of sink limitations. These data suggest that seve ral members of the lipoxygenase multigene family are involved in assim ilate partitioning. The possible involvement of jasmonic acid as a sig naling molecule regulating assimilate partitioning into the vegetative storage proteins and lipoxygenases was directly assessed by determini ng the endogenous level of jasmonic acid in leaves from plants with th eir pods removed. Them was no rise in the level of endogenous jasmonic acid coincident with the strong increase in both vlxC and vegetative storage protein YspB transcripts in response to sink limitation. Thus, expression of the vegetative lipoxygenases and vegetative storage pro teins is not regulated by jasmonic acid in sink-limited leaves.