Department of Genetics and Biotechnology, St. Petersburg State University, 199034, St. Petersburg, Russia.
Department of Genetics and Biotechnology, St. Petersburg State University, 199034, St. Petersburg, Russia; All-Russia Research Institute for Agricultural Microbiology, 196608, St. Petersburg, Russia.
J Plant Physiol. 2018 Feb;221:94-100. doi: 10.1016/j.jplph.2017.12.005. Epub 2017 Dec 9.
CLAVATA (CLV) system including CLV1-like kinase and CLE-peptides is the part of the AON (autoregulation of nodulation) that controls nodule number in legume plants. Moreover, CLV system plays a key role in meristems, where it regulates the expression of WOX genes in organizing centers. Recently, we found that WOX5 homolog in pea is also expressed in nodules and in tumors induced by Agrobacterium tumefaciens. Based on this, we hypothesized that both nodules and agrobacterial tumors may be regulated by and may trigger the same components of AON, including the same WOX and CLV genes. Here, we found that pea plants with agrobacterial tumors induced prior to rhizobial inoculation had reduced the number of nodules. This effect was absent in pea sym29 mutant defective in CLV1-like kinase, the key component of AON. That suggests that agrobacterial tumors may produce a signal activating CLV1-like kinase and thereby decrease the nodule number. Since CLE peptides are known to act upstream of CLV1-like kinase, expression analysis of CLE genes has been performed both in developing nodules and tumors. Overall, 45 CLE genes were identified, and among them nine nodulation-induced CLEs were found in pea. In agrobacterial tumors, no expression of nodule-specific CLE genes the homologues of which inhibit nodulation in other legumes was observed. However, increased expression of two other nodulation-induced CLE genes was observed in agrobacterial tumors, suggesting that CLE genes are expressed in tumors that may still contribute to autoregulatory processes suppressing nodulation.
CLAVATA (CLV) 系统包括 CLV1 样激酶和 CLE 肽，是豆科植物中控制结瘤数的 AON（结瘤自动调节）的一部分。此外，CLV 系统在分生组织中起关键作用，在那里它调节组织中心中 WOX 基因的表达。最近，我们发现豌豆中的 WOX5 同源物也在根瘤和根癌农杆菌诱导的肿瘤中表达。基于此，我们假设根瘤和农杆菌肿瘤可能受到 AON 相同成分的调节，并可能触发相同的 WOX 和 CLV 基因。在这里，我们发现与根瘤菌接种前诱导的根癌农杆菌肿瘤的豌豆植物的结瘤数减少。在 AON 的关键成分 CLV1 样激酶缺陷的豌豆 sym29 突变体中，这种效应不存在。这表明根癌农杆菌肿瘤可能产生激活 CLV1 样激酶的信号，从而减少结瘤数。由于已知 CLE 肽在上游作用于 CLV1 样激酶，因此对发育中的根瘤和肿瘤中的 CLE 基因进行了表达分析。总体而言，鉴定出 45 个 CLE 基因，其中包括豌豆中的 9 个结瘤诱导型 CLEs。在根癌农杆菌肿瘤中，没有观察到抑制其他豆科植物结瘤的结瘤特异性 CLE 基因同源物的表达。然而，在根癌农杆菌肿瘤中观察到两个其他结瘤诱导型 CLE 基因的表达增加，表明 CLE 基因在可能仍有助于抑制结瘤的自动调节过程的肿瘤中表达。
