Calcium distribution and function in the glandular trichomes of Lavandula pinnata L.

HUANG, S-S. (The Institute of Chinese Medicine of Guangdong province, Guangzhou, 510520, China), J.-P. LIAO (South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China). AND B. K. KIRCHOFF (University of North Carolina at Greensboro, Department of Biology, Greensboro, NC 27402), Calcium distribution and function in the glandular trichomes of Lavandula pinnata L. J. Torrey Bot. Soc. 137: 1-15. 2010.-Calcium distribution during peltate and capitate glandular trichome development in Lavandula pinnata L. was examined with the potassium antimonate precipitation method. In order to establish a role for calcium in the secretory process and elucidate calcium function in the glands, the effects of calcium removal were investigated by treatment with nifedipine (Nif, a calcium channel blocker) and Ethylene glycol-bis (2-aminoethyl ether)-N, N, N', N'-tetraacetic acid (EGTA, a calcium chelator). Untreated, mature glands accumulate many calcium precipitates in the subcuticular space and adjacent cell wall during secretion. In Nif or EGTA treated plants these precipitates disappear, and the amount of secretory product is drastically reduced. Calcium removal also results in a reduction in gland density, cells with decreased cytoplasmic density, formation of a lax cell wall, abnormal formation of the subcuticular space, thinning of the cuticle, and the presence of multivesicular bodies near the plasma membrane. At the post-secretory stage, calcium precipitates are common on the degenerating organelles. These results support a role for calcium in gland development, secretion, and programmed cell death.