Ozga Jocelyn A, Yu Jody, Reinecke Dennis M
Plant Physiology and Molecular Biology Research Group, Department of Agricultural, Food, and Nutritional Science, University of Alberta, Edmonton, Alberta, Canada T6G 2P5.
Plant Physiol. 2003 Mar;131(3):1137-46. doi: 10.1104/pp.102.015974.
To understand further how pollination, seeds, auxin (4-chloroindole-3-acetic acid [4-Cl-IAA]), and gibberellins (GAs) regulate GA biosynthesis in pea (Pisum sativum) fruit, we studied expression of the gene PsGA3ox1 that codes for the enzyme that converts GA(20) to biologically active GA(1) using real-time reverse transcription-polymerase chain reaction analysis. PsGA3ox1 mRNA levels were minimally detectable in prepollinated pericarps and ovules (-2 d after anthesis [DAA]), increased dramatically after pollination (0 DAA), then decreased by 1 DAA. Seed PsGA3ox1 mRNA levels increased at 4 DAA and again 8 to 12 DAA, when seed development was rapid. Pericarp PsGA3ox1 mRNA levels peaked coincidentally with rapid pod diameter expansion (6-10 DAA) to accommodate the growing seeds. The effects of seeds and hormones on the expression of pericarp PsGA3ox1 were investigated over a 24-h treatment period. Pericarp PsGA3ox1 mRNA levels gradually increased from 2 to 3 DAA when seeds were present; however, when the seeds were removed, the pericarp transcript levels dramatically declined. When 2-DAA deseeded pericarps were treated with 4-Cl-IAA, PsGA3ox1 mRNA levels peaked 4 h after hormone treatment (270-fold increase), then decreased. PsGA3ox1 mRNA levels in deseeded pericarps treated with indole-3-acetic acid or GA(3) were the same or lower than deseeded controls. These data show that PsGA3ox1 is expressed and developmentally regulated in pea pericarps and seeds. These data also show that pericarp PsGA3ox1 expression is hormonally regulated and suggest that the conversion of GA(20) to GA(1) occurs in the pericarp and is regulated by the presence of seeds and 4-Cl-IAA for fruit growth.
为了进一步了解授粉、种子、生长素（4-氯吲哚-3-乙酸[4-Cl-IAA]）和赤霉素（GAs）如何调节豌豆（Pisum sativum）果实中的GA生物合成，我们使用实时逆转录-聚合酶链反应分析研究了编码将GA(20)转化为生物活性GA(1)的酶的基因PsGA3ox1的表达。在授粉前的果皮和胚珠中（开花后-2天[DAA]），PsGA3ox1 mRNA水平几乎检测不到，授粉后（0 DAA）急剧增加，然后在1 DAA时下降。种子PsGA3ox1 mRNA水平在4 DAA时增加，并在种子发育迅速的8至12 DAA时再次增加。果皮PsGA3ox1 mRNA水平在豆荚直径迅速扩大（6-10 DAA）以适应种子生长时达到峰值。在24小时的处理期内研究了种子和激素对果皮PsGA3ox1表达的影响。当有种子时，果皮PsGA3ox1 mRNA水平从2 DAA到3 DAA逐渐增加；然而，当种子被去除时，果皮转录水平急剧下降。当用4-Cl-IAA处理2-DAA去籽果皮时，PsGA3ox1 mRNA水平在激素处理后4小时达到峰值（增加270倍），然后下降。用吲哚-3-乙酸或GA(3)处理的去籽果皮中的PsGA3ox1 mRNA水平与去籽对照相同或更低。这些数据表明PsGA3ox1在豌豆果皮和种子中表达并受到发育调控。这些数据还表明果皮PsGA3ox1表达受激素调控，并表明GA(20)向GA(1)的转化发生在果皮中，并受种子和4-Cl-IAA的存在调控以促进果实生长。
