Sugar-Hormone Cross-Talk in Seed Development: Two Redundant Pathways of IAA Biosynthesis Are Regulated Differentially in the Invertase-Deficient miniature1 (mn1) Seed Mutant in Maize
Sugar-Hormone Cross-Talk in Seed Development: Two Redundant Pathways of IAA Biosynthesis Are Regulated Differentially in the Invertase-Deficient miniature1 (mn1) Seed Mutant in Maize
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DOI：
10.1093/mp/ssq057
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发表时间：
2010-11-01
期刊：
影响因子：
27.5
通讯作者：
Kumar, Dibyendu
中科院分区：
文献类型：
--
作者：
Chourey, Prem S.;Li, Qin-Bao;Kumar, Dibyendu
miniature 1（mn 1）种子表型是编码细胞壁转化酶的Mn 1基因座的功能缺失突变;其缺陷导致多效性变化，包括在整个种子发育过程中糖水平改变和IAA水平降低。为了了解这种糖-激素关系的分子细节，我们已经开始了对玉米种子发育中IAA生物合成基因的研究。IAA生物合成的两个依赖于色氨酸的途径，色胺（TAM）和吲哚-3-异丁酸（IPA），特别令人感兴趣。我们报告的IPA分支的胚乳特异性ZmTARelated 1（ZmTar 1）基因的分子分离和表征，我们最近还报道了TAM分支的ZmYuc 1基因。比较基因表达分析表明：（1）ZmTar 1转录物的水平比ZmYuc 1高约10倍;（2）虽然这两个基因在授粉后8-12天表达量最高，与IAA水平的早期高峰一致，在Mn 1和mn 1胚乳中，这两种酶在12和16 DAP表现出高度分歧（拮抗）的反应，但在20和28 DAP表现出相似的模式。然而，ZmTAR 1蛋白的Western印迹分析显示不一致的蛋白/转录表达模式。总体而言，这些数据报告新的观察多余的色氨酸依赖途径生长素的生物合成发育中的玉米种子，并建议，IAA在这个重要的水槽的稳态控制是非常复杂的，可能是受蔗糖代谢和发育信号。
The miniature1 (mn1) seed phenotype is a loss-of-function mutation at the Mn1 locus that encodes a cell wall invertase; its deficiency leads to pleiotropic changes including altered sugar levels and decreased levels of IAA throughout seed development. To understand the molecular details of such a sugar-hormone relationship, we have initiated studies on IAA biosynthesis genes in developing seeds of maize. Two tryptophan-dependent pathways of IAA biosynthesis, tryptamine (TAM) and indole-3-pyruvic acid (IPA), are of particular interest. We report on molecular isolation and characterization of an endosperm-specific ZmTARelated1 (ZmTar1) gene of the IPA branch; we have also reported recently on ZmYuc1 gene in the TAM branch. Comparative gene expression analyses here have shown that (1) the ZmTar1 transcripts were approximately 10-fold higher levels than the ZmYuc1; (2) although both genes showed the highest level of expression at 8-12 d after pollination (DAP) coincident with an early peak in IAA levels, the two showed highly divergent (antagonistic) response at 12 and 16 DAP but similar patterns at 20 and 28 DAP in the Mn1 and mn1 endosperm. The Western blot analyses for the ZmTAR1 protein, however, displayed disconcordant protein/transcript expression patterns. Overall, these data report novel observations on redundant trp-dependent pathways of auxin biosynthesis in developing seeds of maize, and suggest that homeostatic control of IAA in this important sink is highly complex and may be regulated by both sucrose metabolism and developmental signals.