Cabral Danila, Forero Ballesteros Helkin, de Melo Bruno Paes, Lourenço-Tessutti Isabela Tristan, Simões de Siqueira Kércya Maria, Obicci Luciana, Grossi-de-Sa Maria Fatima, Hemerly Adriana S, de Almeida Engler Janice
INRAE, Université Côte d'Azur, CNRS, ISA, Sophia Antipolis, France.
Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
Front Plant Sci. 2021 Apr 30;12:636663. doi: 10.3389/fpls.2021.636663. eCollection 2021.
The biogenesis of root-knot nematode ( spp.)-induced galls requires the hyperactivation of the cell cycle with controlled balance of mitotic and endocycle programs to keep its homeostasis. To better understand gall functioning and to develop new control strategies for this pest, it is essential to find out how the plant host cell cycle programs are responding and integrated during the nematode-induced gall formation. This work investigated the spatial localization of a number of gene transcripts involved in the pre-replication complex during DNA replication in galls and report their akin colocation with the cell cycle S-phase regulator Armadillo BTB Arabidopsis Protein 1 (ABAP1). ABAP1 is a negative regulator of pre-replication complex controlling DNA replication of genes involved in control of cell division and proliferation; therefore, its function has been investigated during gall ontogenesis. Functional analysis was performed upon knockdown and overexpression in . We detected promoter activity and localized ABAP1 protein in galls during development, and its overexpression displayed significantly reduced gall sizes containing atypical giant cells. Profuse expression also impaired gall induction and hindered nematode reproduction. Remarkably, knockdown likewise negatively affected gall and nematode development, suggesting its involvement in the feeding site homeostasis. Microscopy analysis of cleared and nuclei-stained whole galls revealed that ABAP1 accumulation resulted in aberrant giant cells displaying interconnected nuclei filled with enlarged heterochromatic regions. Also, imbalanced expression caused changes in expression patterns of genes involved in the cell division control as demonstrated by qRT-PCR. , , , and mRNA levels were significantly increased in galls upon overexpression, possibly contributing to the structural changes in galls during nematode infection. Overall, data obtained in galls reinforced the role of controlling DNA replication and mitosis and, consequently, cell proliferation. expression might likely take part of a highly ordered mechanism balancing of cell cycle control to prevent gall expansion. expression might prevent galls to further expand, limiting excessive mitotic activity. Our data strongly suggest that as a unique plant gene is an essential component for cell cycle regulation throughout gall development during nematode infection and is required for feeding site homeostasis.
根结线虫诱导的虫瘿生物发生需要细胞周期的过度激活，并通过有丝分裂和内复制周期程序的平衡控制来维持其稳态。为了更好地理解虫瘿的功能并开发针对这种害虫的新控制策略，弄清楚植物宿主细胞周期程序在根结线虫诱导的虫瘿形成过程中是如何响应和整合的至关重要。这项研究调查了虫瘿DNA复制过程中参与前复制复合体的多个基因转录本的空间定位，并报告了它们与细胞周期S期调节因子犰狳BTB拟南芥蛋白1（ABAP1）的共定位情况。ABAP1是前复制复合体的负调节因子，控制参与细胞分裂和增殖调控的基因的DNA复制；因此，在虫瘿发育过程中对其功能进行了研究。在拟南芥中进行了基因敲低和过表达后的功能分析。我们检测了ABAP1的启动子活性，并在虫瘿发育过程中对其蛋白进行了定位，其过表达显示含有非典型巨型细胞的虫瘿大小显著减小。大量的ABAP1表达也损害了虫瘿诱导并阻碍了线虫繁殖。值得注意的是，ABAP1基因敲低同样对虫瘿和线虫发育产生负面影响，表明其参与了取食位点的稳态维持。对透明和细胞核染色的整个虫瘿进行显微镜分析发现，ABAP1的积累导致异常巨型细胞出现，细胞核相互连接，充满扩大的异染色质区域。此外，如qRT-PCR所示，ABAP1表达失衡导致参与细胞分裂控制的基因表达模式发生变化。ABAP1过表达时，虫瘿中CYCB1;1、CYCB1;2、CYCA2;3和CYCA3;1的mRNA水平显著增加，这可能导致线虫感染期间虫瘿的结构变化。总体而言，在虫瘿中获得的数据加强了ABAP1控制DNA复制和有丝分裂从而调控细胞增殖的作用。ABAP1表达可能参与了一种高度有序的机制，平衡细胞周期控制以防止虫瘿扩大。ABAP1表达可能会阻止虫瘿进一步扩大，限制过度的有丝分裂活性。我们的数据强烈表明，ABAP1作为一个独特的植物基因，是线虫感染期间整个虫瘿发育过程中细胞周期调控的重要组成部分，也是取食位点稳态维持所必需的。
