Gene expression studies on developing kernels of maize sucrose synthase (SuSy) mutants show evidence for a third SuSy gene
Gene expression studies on developing kernels of maize sucrose synthase (SuSy) mutants show evidence for a third SuSy gene
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DOI：
10.1023/a:1014457901992
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发表时间：
2002-05-01
影响因子：
5.1
通讯作者：
Datta, R
中科院分区：
文献类型：
--
作者：
Carlson, SJ;Chourey, PS;Datta, R
先前的研究已经确定了两个具有组织和细胞特异性但功能冗余的蔗糖合酶（SuSy）基因，Sh1和Sus1，它们编码生化性质相似的同工酶SH1和SUS1（先前分别称为SS1和SS2）。在此我们报道了玉米中第三个SuSy基因Sus3的证据，它与双子叶植物的SuSy基因比与单子叶植物的更为相似。对发育中的籽粒和其他组织进行的RNA和/或蛋白质印迹分析显示了Sus3表达的证据，尽管其在三个SuSy基因产物中处于最低的稳态水平，且没有独特的组织特异性模式。对缺乏或缺失胚特异性SUS1蛋白的shlsusl - 1胚胎进行的免疫印迹分析显示出一条蛋白质条带，我们将其归因于Sus3基因，并且它可能对双突变体胚胎中残留的酶活性有贡献。我们还研究了缺失99.5% SuSy酶活性的双突变体shlsusl - 1发育中的种子，以寻找糖代谢的几个基因共同调控的证据。我们发现与同系的shlSusl和shlSusl籽粒相比，双突变体中Miniature - 1编码的细胞壁转化酶2和蔗糖转运蛋白（Sut）mRNA的稳态水平显著降低。MW基因的下调也反映在细胞壁转化酶活性的显著降低上。在蔗糖磷酸合酶、UDP - 葡萄糖焦磷酸化酶和ADP - 葡萄糖焦磷酸化酶的表达中未观察到共同调控的变化。
Previous studies have identified two tissue- and cell-specific, yet functionally redundant, sucrose synthase (SuSy) genes, Sh1 and Sus1, which encode biochemically similar isozymes, SH1 and SUS1 (previously referred to as SS1 and SS2, respectively). Here we report evidence for a third SuSy gene in maize, Sus3, which is more similar to dicot than to monocot SuSys. RNA and/or protein blot analyses on developing kernels and other tissues show evidence of expression of Sus3, although at the lowest steady-state levels of the three SuSy gene products and without a unique pattern of tissue specificity. Immunoblots of shlsusl-l embryos that are either lacking or deficient for the embryo-specific SUS1 protein have shown a protein band which we attribute to the Sus3 gene, and may contribute to the residual enzyme activity seen in embryos of the double mutant. We also studied developing seeds of the double mutant shlsusl-l, which is missing 99.5% of SuSy enzyme activity, for evidence of co-regulation of several genes of sugar metabolism. We found a significant reduction in the steady-state levels of Miniature-1 encoded cell wall invertase2, and Sucrose transporter (Sut) mRNAs in the double mutant. relative to the lineage-related shlSusl and shlSusl kernels. Down-regulation of the MW gene was also reflected in significant reductions in cell wall invertase activity. Co-regulatory changes were not seen in the expression of Sucrose phosphate synthase, UDP-glucose pyrophosphorylase, and ADP-glucose pyrophosphorylase.