Graduate School of Life and Environmental Science, University of Tsukuba, Tsukuba, Ibaraki, 305-8572, Japan.
Department of Biosciences, Teikyo University, Utsunomiya, Tochigi, 320-8551, Japan.
J Plant Res. 2023 Nov;136(6):865-877. doi: 10.1007/s10265-023-01494-0. Epub 2023 Sep 14.
Plants are exposed to a variety of biotic and abiotic stresses, including wounding at the stem. The healing process (tissue reunion) begins immediately after stem wounding. The plant hormone auxin plays an important role during tissue reunion. In decapitated stems, auxin transport from the shoot apex is reduced and tissue reunion does not occur but is restored by application of indole-3-acetic acid (IAA). In this study, we found that plasmodesmata callose binding protein 2 (PDCB2) affects the expansion of the cambium/phloem region via changes in auxin response during the process of tissue reunion. PDCB2 was expressed in the cortex and endodermis on the incised side of stems 1-3 days after incision. PDCB2-knockout plants showed reduced callose deposition at plasmodesmata and DR5::GUS activity in the endodermis/cortex in the upper region of the incision accompanied by an increase in size of the cambium/phloem region during tissue reunion. In addition, PIN(PIN-FORMED)3, which is involved in lateral auxin transport, was induced by auxin in the cambium/phloem and endodermis/cortex in the upper part of the incision in wild type, but its expression of PIN3 was decreased in pdcb2 mutant. Our results suggest that PDCB2 contributes to the regulation of cambium/phloem development via auxin response.
植物会受到各种生物和非生物胁迫的影响，包括茎部受伤。受伤后，植物会立即启动愈合过程（组织重组）。植物激素生长素在组织重组过程中起着重要作用。在去顶的茎中，来自茎尖的生长素运输减少，组织无法重组，但通过施加吲哚-3-乙酸（IAA）可以恢复。在这项研究中，我们发现质膜胞间连丝结合蛋白 2（PDCB2）通过改变组织重组过程中的生长素反应，影响形成层/韧皮部区域的扩展。在切口后 1-3 天，PDCB2 在茎的切口侧皮层和内皮层中表达。PDCB2 敲除植物在切口上部的质膜胞间连丝处的胼胝质沉积减少，DR5::GUS 活性在内皮层/皮层中降低，同时在组织重组过程中形成层/韧皮部区域增大。此外，参与侧方生长素运输的 PIN（PIN-FORMED）3 在野生型切口上部的形成层/韧皮部和内皮层/皮层中被生长素诱导，但在 pdcb2 突变体中，PIN3 的表达减少。我们的结果表明，PDCB2 通过生长素反应有助于调节形成层/韧皮部的发育。
