Two cytosolic glutamine synthetase isoforms of maize are specifically involved in the control of grain production
Two cytosolic glutamine synthetase isoforms of maize are specifically involved in the control of grain production
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DOI：
10.1105/tpc.106.042689
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发表时间：
2006-11-01
期刊：
影响因子：
11.6
通讯作者：
Hirel, Bertrand
中科院分区：
文献类型：
--
作者：
Martin, Antoine;Lee, Judy;Hirel, Bertrand
通过研究敲除突变对玉米籽粒产量的影响，研究了两种胞质玉米谷氨酰胺合成酶同工酶（GS 1），Gln 1 -3和Gln 1 -4基因的产物的作用。在gln 1 -3和gln 1 -4单突变体和gln 1 -3 gln 1 -4双突变体中，GS mRNA表达受损，导致GS 1蛋白和活性降低。gln 1 -4表型显示减少的籽粒大小和gln 1 -3减少的籽粒数，与两种表型显示在gln 1 -3 gln 1 -4。然而，在成熟时，地上部生物量的生产没有修改的单突变体或双突变体，这表明在这两个突变体的粮食生产的具体影响。Asn增加的突变体的叶片在灌浆过程中，这表明它可能积累规避铵积累造成较低的GS 1活性。韧皮部汁液分析表明，不像谷氨酰胺，天冬酰胺不能有效地运输到发展中的内核，显然导致减少内核生产。当Gln 1 -3在叶片中组成型过表达时，籽粒数增加30%，进一步证明GS1-3在籽粒产量中起主要作用。细胞免疫化学和原位杂交显示，GS 1 -3是存在于叶肉细胞，而GS 1 -4是专门定位于束鞘细胞。这两种GS 1同工酶在其组织特异性定位方面发挥着非冗余的作用。
The roles of two cytosolic maize glutamine synthetase isoenzymes (GS1), products of the Gln1-3 and Gln1-4 genes, were investigated by examining the impact of knockout mutations on kernel yield. In the gln1-3 and gln1-4 single mutants and the gln1-3 gln1-4 double mutant, GS mRNA expression was impaired, resulting in reduced GS1 protein and activity. The gln1-4 phenotype displayed reduced kernel size and gln1-3 reduced kernel number, with both phenotypes displayed in gln1-3 gln1-4. However, at maturity, shoot biomass production was not modified in either the single mutants or double mutants, suggesting a specific impact on grain production in both mutants. Asn increased in the leaves of the mutants during grain filling, indicating that it probably accumulates to circumvent ammonium buildup resulting from lower GS1 activity. Phloem sap analysis revealed that unlike Gln, Asn is not efficiently transported to developing kernels, apparently causing reduced kernel production. When Gln1-3 was overexpressed constitutively in leaves, kernel number increased by 30%, providing further evidence that GS1-3 plays a major role in kernel yield. Cytoimmunochemistry and in situ hybridization revealed that GS1-3 is present in mesophyll cells, whereas GS1-4 is specifically localized in the bundle sheath cells. The two GS1 isoenzymes play nonredundant roles with respect to their tissue-specific localization.