Spatial and temporal distribution of the major isoforms of puroindolines (puroindoline-a and puroindoline-b) and non specific lipid transfer protein (ns-LTPle(1)) of Triticum aestivum seeds. Relationships with their in vitroantifungal properties

In wheat endosperm, the main isoforms of puroindolines (PIN-a and PIN-b) an d nonspecific lipid transfer protein (ns-LTP1e(1)), structurally related li pid binding proteins, were asynchronously synthesized during maturation and are partially degraded during germination. These proteins are not detected in roots and hypocotyls of seedlings, while ns-LTP1e(1), but not PINs, was synthesized during germination in the scutellum and/or mesocotyl. In matur e wheat seeds, ns-LTP1-e(1) was specifically localised within aleurone cell s but not in cell walls in marked contrast with most other plant ns-LTP1s. PINs are both located in the starchy endosperm and in the aleurone layer. I n the latter cells, PINs and ns-LTP1-e(1) were both localised in small incl usions within protein-rich aleurone grains. In the mature starchy endosperm , PINs were localised in the protein matrix and at the interface between st arch granules and protein matrix. It was shown that both PIN-a and PIN-b, h ave antifungal properties in vitro and a synergistic enhancement of the ant ifungal properties of alpha-purothionins (alpha-PTH) was observed in the pr esence of PINs. This synergism could have biological significance since alp ha-PTH and PINs are both located in the protein matrix of starchy endosperm . ns-LTP1e(1) is not capable to inhibit growth of fungi and a synergy rathe r weak in comparison with PINs was also observed between ns-LTP1e(1) and al pha-PTH. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.