LAT52 protein is essential for tomato pollen development: pollen expressing antisense LAT52 RNA hydrates and germinates abnormally and cannot achieve fertilization

MUSCHIETTI, JORGE; DIRCKS, LORI; MCCORMICK, SHEILA

PLANT JOURNAL

Año: 1994 vol. 3 p. 321 - 328

0960-7412

The LAT52 gene of tomato is expressed in a pollen-specific manner. We show that LAT52 encodes a heat stable, glycosylated protein that traverses the secretory pathway when expressed in a baculovirus expression system. The LAT52 protein shows some similarity with Kunitz trypsin inhibitors and with pollen proteins from maize, rice and olive, but the biological function of these pollen proteins is unknown. To test whether the LAT52 protein plays an important role during pollen development, we transformed tomato plants with an antisense LAT52 gene driven by the LAT52 promoter. Because the LAT52 gene is expressed gametophytically, only 50% of the pollen of the primary transformants would be expected to express the antisense construct. Self-progeny of 19 of the primary transformants showed the predicted 3:1 segregation for a single locus insertion of the linked kanamycin resistance gene. However, the self-progeny of the other 32 primary transformants showed a 1:1 segregation pattern and could not transmit the linked kanamycin resistance gene through the male. We examined a subset of these 1:1 segregation class plants in detail. The pollen showed lower levels of LAT52 mRNA and LAT52 protein when compared to wild type. In vitro, approximately 50% of the pollen grains appear to hydrate abnormally; this anomaly is not present when the same pollen grains are incubated in a medium with higher water potential. In vivo pollination experiments showed that the growth of around 50% of the pollen tubes is arrested in the style. The 3:1 segregation class plants showed no significant differences from untransformed control plants. Taken together, our results show a direct correlation between the reduced expression of LAT52 protein and abnormal pollen function, and suggest that the LAT52 protein plays a role in pollen hydration and/or pollen germination.