Nagpal Punita, Ellis Christine M, Weber Hans, Ploense Sara E, Barkawi Lana S, Guilfoyle Thomas J, Hagen Gretchen, Alonso José M, Cohen Jerry D, Farmer Edward E, Ecker Joseph R, Reed Jason W
Department of Biology, University of North Carolina at Chapel Hill, CB #3280, Coker Hall, Chapel Hill, NC 27599-3280, USA.
Development. 2005 Sep;132(18):4107-18. doi: 10.1242/dev.01955. Epub 2005 Aug 17.
Pollination in flowering plants requires that anthers release pollen when the gynoecium is competent to support fertilization. We show that in Arabidopsis thaliana, two paralogous auxin response transcription factors, ARF6 and ARF8, regulate both stamen and gynoecium maturation. arf6 arf8 double-null mutant flowers arrested as infertile closed buds with short petals, short stamen filaments, undehisced anthers that did not release pollen and immature gynoecia. Numerous developmentally regulated genes failed to be induced. ARF6 and ARF8 thus coordinate the transition from immature to mature fertile flowers. Jasmonic acid (JA) measurements and JA feeding experiments showed that decreased jasmonate production caused the block in pollen release, but not the gynoecium arrest. The double mutant had altered auxin responsive gene expression. However, whole flower auxin levels did not change during flower maturation, suggesting that auxin might regulate flower maturation only under specific environmental conditions, or in localized organs or tissues of flowers. arf6 and arf8 single mutants and sesquimutants (homozygous for one mutation and heterozygous for the other) had delayed stamen development and decreased fecundity, indicating that ARF6 and ARF8 gene dosage affects timing of flower maturation quantitatively.
开花植物的授粉需要花药在雌蕊具备支持受精能力时释放花粉。我们发现，在拟南芥中，两个同源的生长素响应转录因子ARF6和ARF8调控雄蕊和雌蕊的成熟。arf6 arf8双缺失突变体花朵发育停滞，成为不育的闭合花蕾，花瓣短小，雄蕊花丝短，花药不开裂，不释放花粉，雌蕊不成熟。许多受发育调控的基因未能被诱导表达。因此，ARF6和ARF8协调了从不成熟到成熟可育花的转变。茉莉酸（JA）测量和JA饲喂实验表明，茉莉酸产量降低导致花粉释放受阻，但未导致雌蕊发育停滞。双突变体的生长素响应基因表达发生了改变。然而，在花成熟过程中，整朵花的生长素水平并未改变，这表明生长素可能仅在特定环境条件下，或在花的局部器官或组织中调控花的成熟。arf6和arf8单突变体及半突变体（一个突变纯合，另一个突变杂合）的雄蕊发育延迟，育性降低，这表明ARF6和ARF8的基因剂量定量影响花成熟的时间。
