Instituto Agronômico do Paraná, IAPAR, LBI-AMG, Londrina, Paraná, Brazil.
Plant Biol (Stuttg). 2011 May;13(3):462-71. doi: 10.1111/j.1438-8677.2010.00400.x. Epub 2010 Oct 29.
As a first step towards understanding the physiological role and regulation of the expansin gene (EXP) family in Coffea arabica fruits during growth and maturation, we identified 11 expansin genes, nine belonging to the α-expansin family (EXPA), one EXLA and one EXLB, through in silico analysis of expressed sequence tags (ESTs). Within the α-expansin family, three isoforms were selected for detailed examination based on their high expression in coffee fruits or because they were specifically induced during different fruit developmental stages, according to the EST information. The expression patterns were analysed in different fruit tissues (perisperm, endosperm and pericarp) of C. arabica cv. IAPAR-59 and C. arabica cv. IAPAR-59 Graúdo, the latter being a closely related cultivar with a larger fruit size. Accumulation of CaEXPA1 and CaEXPA3 transcripts was high in the perisperm (tissue responsible for coffee bean size) and in the early stages of pericarp development. Transcripts of CaEXPA2 were detected only in the pericarp during the later stages of fruit maturation and ripening. There was no detectable transcription of the three EXPs analysed in the endosperm. The observed differences in mRNA expression levels of CaEXPA1 and CaEXP3 in the perisperm of IAPAR-59 and IAPAR-59 Graúdo suggest the participation of these two isoforms in the regulation of grain size.
为了初步了解在咖啡果实生长和成熟过程中膨胀素基因（EXP）家族的生理功能和调控机制，我们通过对表达序列标签（EST）的生物信息学分析，鉴定了 11 个膨胀素基因，其中 9 个属于α-膨胀素家族（EXPA），1 个 EXLA 和 1 个 EXLB。在α-膨胀素家族中，根据 EST 信息，选择了三个同工型进行详细研究，因为它们在咖啡果实中表达水平较高，或者在不同的果实发育阶段特异性诱导。在阿拉比卡咖啡品种 IAPAR-59 和 IAPAR-59 Graúdo 的不同果实组织（胚乳、胚和果皮）中分析了表达模式，后者是一个亲缘关系较近的品种，果实较大。CaEXPA1 和 CaEXPA3 的转录物在胚乳（负责咖啡豆大小的组织）和果皮发育的早期阶段积累量较高。在果实成熟和成熟的后期阶段，仅在果皮中检测到 CaEXPA2 的转录物。在胚乳中未检测到三种 EXP 的转录。在 IAPAR-59 和 IAPAR-59 Graúdo 的胚乳中，CaEXPA1 和 CaEXP3 的 mRNA 表达水平存在差异，表明这两个同工型参与了粒大小的调控。
