KNOTTED1-LIKE HOMEOBOX 3: a new regulator of symbiotic nodule development.
KNOTTED1-LIKE HOMEOBOX 3: a new regulator of symbiotic nodule development.
复制标题
DOI：
10.1093/jxb/erv414
复制
发表时间：
2015-12
影响因子：
6.9
通讯作者：
Lutova LA
中科院分区：
文献类型：
--
作者：
Azarakhsh M;Kirienko AN;Zhukov VA;Lebedeva MA;Dolgikh EA;Lutova LA
KNOX 3基因参与了蒺藜苜蓿和豌豆共生根瘤的发育，为它可能调控根瘤形成过程中细胞分裂素的生物合成/活化提供了证据。KNOX转录因子主要通过影响植物激素代谢来调控植物发育的各个方面。特别是，KNOX TF SHOOTMERISTEMLESS激活茎顶端分生组织中的细胞分裂素生物合成异戊烯基转移酶（IPT）基因。然而，迄今为止，还没有研究过KNOX转录因子在共生根瘤发育中的作用以及它们在结瘤过程中对植物激素代谢的可能影响。细胞分裂素是一种众所周知的根瘤发育调节因子，在根瘤原基形成过程中对细胞分裂的调节起关键作用。最近，IPT基因的激活被证明发生在排卵期间。因此，假设KNOX TF可以调节根瘤发育并在结瘤后激活细胞分裂素生物合成。本研究分析了蒺藜苜蓿不同KNOX基因的表达。和豌豆Pisum sativum L.其中，KNOX 3基因在两个物种的根瘤菌接种反应上调。pKNOX 3：：GUS在根瘤原基发育过程中具有活性。KNOX 3异位表达导致在没有细菌接种的情况下在转基因根上形成结节样结构，这种表型类似于先前描述的具有细胞分裂素受体组成性激活的豆类。此外，在MtKNOX 3敲低的转基因根中，发现A型细胞分裂素应答基因的下调，以及MtIPT 3和LONELYGUY 2（MtLOG 2）基因参与细胞分裂素激活。这些结果表明，KNOX 3基因参与了豆科植物共生根瘤的发育，并可能调控根瘤发育过程中细胞分裂素的生物合成/活化。
KNOX3 gene is involved in symbiotic nodule development in Medicago truncatula and Pisum sativum, providing evidence that it may regulate cytokinin biosynthesis/activation upon nodulation. KNOX transcription factors (TFs) regulate different aspects of plant development essentially through their effects on phytohormone metabolism. In particular, KNOX TF SHOOTMERISTEMLESS activates the cytokinin biosynthesis ISOPENTENYL TRANSFERASE (IPT) genes in the shoot apical meristem. However, the role of KNOX TFs in symbiotic nodule development and their possible effects on phytohormone metabolism during nodulation have not been studied to date. Cytokinin is a well-known regulator of nodule development, playing the key role in the regulation of cell division during nodule primordium formation. Recently, the activation of IPT genes was shown to take place during nodulation. Therefore, it was hypothesized that KNOX TFs may regulate nodule development and activate cytokinin biosynthesis upon nodulation. This study analysed the expression of different KNOX genes in Medicago truncatula Gaertn. and Pisum sativum L. Among them, the KNOX3 gene was upregulated in response to rhizobial inoculation in both species. pKNOX3::GUS activity was observed in developing nodule primordium. KNOX3 ectopic expression caused the formation of nodule-like structures on transgenic root without bacterial inoculation, a phenotype similar to one described previously for legumes with constitutive activation of the cytokinin receptor. Furthermore, in transgenic roots with MtKNOX3 knockdown, downregulation of A-type cytokinin response genes was found, as well as the MtIPT3 and LONELYGUY2 (MtLOG2) gene being involved in cytokinin activation. Taken together, these findings suggest that KNOX3 gene is involved in symbiotic nodule development and may regulate cytokinin biosynthesis/activation upon nodule development in legume plants.