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Characterization and expression of plasma and tonoplast membrane aquaporins in elongating cotton fibers 总被引:2,自引:0,他引:2
Cotton fiber (Gossypium hirsutum L. and G. barbadense L.) is a good model for studies of plant cell elongation and cell wall biogenesis. Aquaporins are ancient membrane channel proteins that facilitate the permeation of water across biological membranes. We studied GhPIP1-2, encoding plasma membrane intrinsic protein, and GhgammaTIP1, encoding tonoplast intrinsic protein, during cotton fiber development. The full-length cDNAs of GhPIP1-2 and GhgammaTIP1 were obtained through 5' RACE. The deduced amino acid sequences of GhPIP1-2 and GhgammaTIP1 share high sequence identity with aquaporins from diverse plant species. Phylogenetic analysis of GhPIP1-2 and GhgammaTIP1 with other plant aquaporins showed that GhPIP1-2 belongs to the PIP1 group of the PIP subfamily and GhgammaTIP1 belongs to the gammaTIP group of the TIP subfamily. GhPIP1-2 and GhgammaTIP1 contain three and two introns, respectively. Genomic Southern blot analysis indicated that GhPIP1-2 and GhgammaTIP1 have several copies and multiple homologous genes in allotetraploid cotton. Northern blot analysis with gene-specific probes and real-time PCR demonstrated that GhPIP1-2 and GhgammaTIP1 are predominantly expressed during cotton fiber elongation, with the highest expression levels at 5 days post-anthesis. Moreover, expression patterns of the two genes in G. hirsutum and G. barbadense are similar, whereas the expression levels in G. barbadense are much lower than that in G. hirsutum. The high and preferential expression of GhPIP1-2 and GhgammaTIP1 during fiber cell elongation suggests that they may play important roles in supporting the rapid influx of water into vacuoles during cotton fiber cell expansion. 相似文献
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植物三萜皂苷生物合成中关键后修饰酶研究进展 总被引:1,自引:0,他引:1
三萜皂苷是由三萜苷元、糖基、糖醛酸等组成的C30萜类化合物,是许多药用植物的主要活性成分,具有广泛的药理作用。三萜皂苷的生物合成包括前体和三萜皂苷骨架的形成以及调控皂苷结构多样性的后修饰。三萜皂苷的后修饰包括三萜骨架的氧化/羟基化和糖基化,分别由不同超基因家族编码的细胞色素P450单加氧酶和糖基转移酶进行催化。三萜皂苷通过后修饰最终可形成多种单体皂苷。目前,已在少数植物中识别和确认了个别与三萜皂苷生物合成相关的关键后修饰酶,发现了部分很可能参与后修饰过程的候选基因。该文就近年来国内外有关三萜皂苷生物合成途径关键后修饰酶的研究进行综述,为进一步开展相关研究和对合成精细途径的解析提供参考。 相似文献