Invertases as Genetic Determinants of Sink Strength

Current population growth combined with increasing development and urbanization worldwide is putting strain on the terrestrial ecosystem’s main carbon sink, forests. One way to combat this increasing demand of decreasing forest resources is to manipulate the carbon allocation patterns in trees to direct carbon into the most desirable organs such as stems to meet industrial demands, or roots to help increase the long term carbon storage capacity in the soil. Plants utilize carbon by partitioning the reduced carbon obtained through photosynthesis into different locations within the cell and subsequently allocating it to sink tissues throughout the plant. We are utilizing Populus as a model system in which to study invertase and its role in sink strength determination with the aim of applying this knowledge to tree breeding and genetic modifications. Using the newly sequenced poplar genome, we have identified eight acid invertase family members through amino acid sequence similarity searches. Three of these family members encode invertases targeted to the vacuole, while the other five invertases are targeted to the apoplast. With only two exceptions, poplar invertases share the intron/ exon structure generally conserved in plants of seven exons separated by six introns. PtIVR1, a vacuolar invertase apparently lacks introns and constitutes the first putative intronless invertase found to date. PtIVR4, another vacuolar invertase is missing the conserved mini-exon NDPN. Although the absence of this exon is unusual, it is not unprecedented in plant invertases.

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Author(s): P. N. Bocock, L. F. Huang, K. E. Koch, John M. Davis

Publication: Tree Improvement and Genetics - Southern Forest Tree Improvement Conference - 2005