Intra- and extracellular lipid composition and associated gene expression patterns during pollen development in <i>Brassica napus</i> Export

@article{citeulike:4075254, abstract = {Pollen development in angiosperms is regulated by the interaction of products contributed by both the gametophytic (haploid) and sporophytic (diploid) genomes. In entomophilous species, lipids are major products of both sporophytic and gametophytic metabolism during pollen development. Mature pollen grains of Brassica napus are shown to contain three major acyl lipid pools as follows: (i) the extracellular tryphine mainly consisting of medium-chain neutral esters; (ii) the intracellular membranes, particularly endoplasmic reticulum, mainly containing phospholipids; and (iii) the intracellular storage lipids, which are mostly triacylglycerols. This paper reports on the kinetics of accumulation of these lipid classes during pollen maturation and the expression patterns of several lipid biosynthetic genes and their protein products that are differentially regulated in developing microspores/ pollen grains (gametophyte) and tapetal cells (sporophyte) of B. napus. Detailed analysis of three members of the stearoyl-ACP desaturase (sad) gene family by Northern blotting, in situ hybridization and RT-PCR showed that the same individual genes were expressed both in gametophytic and sporophytic tissues, although under different temporal regulation. In the tapetum, maximal expression of two marker genes for lipid biosynthesis (sad and ear) occurred at a bud length of 220133 mm, and the corresponding gene products SAD and EAR were detected by Western blotting in 320134 mm buds, coinciding with the maximal rates of tapetal lipid accumulation. These lipids are released following tapetal cell disintegration and are relocated to form the major structural component of the extracellular tryphine layer that coats the mature pollen grain. In contrast, in developing microspores/pollen grains, maximal expression of the lipid marker genes sad, ear, acp and cyb5 was at the 320135 mm bud stages, with the SAD and EAR gene products detected in 420137 mm buds. This pattern of expression coincided with accumulation of the intracellular storage and membrane lipid components of pollen. These results suggest that, although the same genes may be expressed in the sporophytic tapetal cells and in gametophytic tissues, they are regulated differentially leading to the production of the various contrasting lipidic structures that are assembled together to give rise to a viable, fertile pollen grain.}, address = {Department of Brassica and Oilseeds Research, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK}, author = {Piffanelli, Pietro and Ross, Joanne H. E. and Murphy, Denis J.}, citeulike-article-id = {4075254}, citeulike-linkout-0 = {http://dx.doi.org/10.1046/j.1365-313X.1997.11030549.x}, citeulike-linkout-1 = {http://www3.interscience.wiley.com/cgi-bin/abstract/119158846/ABSTRACT}, doi = {10.1046/j.1365-313X.1997.11030549.x}, journal = {The Plant Journal}, keywords = {pollen}, number = {3}, pages = {549--562}, posted-at = {2009-02-20 19:00:41}, priority = {2}, title = {Intra- and extracellular lipid composition and associated gene expression patterns during pollen development in <i>Brassica napus</i>}, url = {http://dx.doi.org/10.1046/j.1365-313X.1997.11030549.x}, volume = {11}, year = {1997} }

TY - JOUR ID - citeulike:4075254 L3 - citeulike-article-id:4075254 N2 - Pollen development in angiosperms is regulated by the interaction of products contributed by both the gametophytic (haploid) and sporophytic (diploid) genomes. In entomophilous species, lipids are major products of both sporophytic and gametophytic metabolism during pollen development. Mature pollen grains of Brassica napus are shown to contain three major acyl lipid pools as follows: (i) the extracellular tryphine mainly consisting of medium-chain neutral esters; (ii) the intracellular membranes, particularly endoplasmic reticulum, mainly containing phospholipids; and (iii) the intracellular storage lipids, which are mostly triacylglycerols. This paper reports on the kinetics of accumulation of these lipid classes during pollen maturation and the expression patterns of several lipid biosynthetic genes and their protein products that are differentially regulated in developing microspores/ pollen grains (gametophyte) and tapetal cells (sporophyte) of B. napus. Detailed analysis of three members of the stearoyl-ACP desaturase (sad) gene family by Northern blotting, in situ hybridization and RT-PCR showed that the same individual genes were expressed both in gametophytic and sporophytic tissues, although under different temporal regulation. In the tapetum, maximal expression of two marker genes for lipid biosynthesis (sad and ear) occurred at a bud length of 220133 mm, and the corresponding gene products SAD and EAR were detected by Western blotting in 320134 mm buds, coinciding with the maximal rates of tapetal lipid accumulation. These lipids are released following tapetal cell disintegration and are relocated to form the major structural component of the extracellular tryphine layer that coats the mature pollen grain. In contrast, in developing microspores/pollen grains, maximal expression of the lipid marker genes sad, ear, acp and cyb5 was at the 320135 mm bud stages, with the SAD and EAR gene products detected in 420137 mm buds. This pattern of expression coincided with accumulation of the intracellular storage and membrane lipid components of pollen. These results suggest that, although the same genes may be expressed in the sporophytic tapetal cells and in gametophytic tissues, they are regulated differentially leading to the production of the various contrasting lipidic structures that are assembled together to give rise to a viable, fertile pollen grain. IS - 3 JF - The Plant Journal AD - Department of Brassica and Oilseeds Research, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK EP - 562 TI - Intra- and extracellular lipid composition and associated gene expression patterns during pollen development in <i>Brassica napus</i> VL - 11 SP - 549 KW - pollen AU - Piffanelli, Pietro AU - Ross, Joanne AU - Murphy, Denis PY - 1997/// UR - http://dx.doi.org/10.1046/j.1365-313X.1997.11030549.x ER -