Veerabagu Manikandan, Rinne Päivi L H, Skaugen Morten, Paul Laju K, van der Schoot Christiaan
Faculty of Biosciences, Department of Plant Sciences, Norwegian University of Life Sciences, Ås, Norway.
Faculty of Chemistry, Biotechnology, and Food Science, Norwegian University of Life Sciences, Ås, Norway.
Front Plant Sci. 2021 Jul 21;12:674031. doi: 10.3389/fpls.2021.674031. eCollection 2021.
Post-embryonic cells contain minute lipid bodies (LBs) that are transient, mobile, engage in organellar interactions, and target plasmodesmata (PD). While LBs can deliver γ-clade 1,3-β-glucanases to PD, the nature of other cargo is elusive. To gain insight into the poorly understood role of LBs in meristems, we investigated their dynamics by microscopy, gene expression analyzes, and proteomics. In developing buds, meristems accumulated LBs, upregulated several LB-specific genes and produced OLEOSINs. During bud maturation, the major gene was strongly downregulated, OLEOSINs disappeared from bud extracts, whereas lipid biosynthesis genes were upregulated, and LBs were enlarged. Proteomic analyses of the LB fraction of dormant buds confirmed that OLEOSINs were no longer present. Instead, we identified the LB-associated proteins CALEOSIN (CLO1), Oil Body Lipase 1 (OBL1), Lipid Droplet Interacting Protein (LDIP), Lipid Droplet Associated Protein1a/b (LDAP1a/b) and LDAP3a/b, and crucial components of the OLEOSIN-deubiquitinating and degradation machinery, such as PUX10 and CDC48A. All mRFP-tagged LDAPs localized to LBs when transiently expressed in . Together with gene expression analyzes, this suggests that during bud maturation, OLEOSINs were replaced by LDIP/LDAPs at enlarging LBs. The LB fraction contained the meristem-related actin7 (ACT7), "myosin XI tail-binding" RAB GTPase C2A, an LB/PD-associated γ-clade 1,3-β-glucanase, and various organelle- and/or PD-localized proteins. The results are congruent with a model in which LBs, motorized by myosin XI-k/1/2, traffic on F-actin, transiently interact with other organelles, and deliver a diverse cargo to PD.
胚后细胞含有微小的脂质体（LBs），这些脂质体是短暂存在、可移动的，参与细胞器相互作用，并靶向胞间连丝（PD）。虽然脂质体可以将γ-分支1,3-β-葡聚糖酶输送到胞间连丝，但其他货物的性质尚不清楚。为了深入了解脂质体在分生组织中鲜为人知的作用，我们通过显微镜观察、基因表达分析和蛋白质组学研究了它们的动态变化。在发育中的芽中，分生组织积累了脂质体，上调了几个脂质体特异性基因并产生了油质蛋白。在芽成熟过程中，主要基因被强烈下调，油质蛋白从芽提取物中消失，而脂质生物合成基因被上调，脂质体增大。对休眠芽脂质体部分的蛋白质组分析证实油质蛋白不再存在。相反，我们鉴定出了与脂质体相关的蛋白质钙脂质体（CLO1）、油体脂肪酶1（OBL1）、脂滴相互作用蛋白（LDIP）、脂滴相关蛋白1a/b（LDAP1a/b）和LDAP3a/b，以及油质蛋白去泛素化和降解机制的关键成分，如PUX10和CDC48A。当在[具体植物名称未给出]中瞬时表达时，所有mRFP标记的LDAPs都定位于脂质体。结合基因表达分析，这表明在芽成熟过程中，增大的脂质体上的油质蛋白被LDIP/LDAPs取代。脂质体部分包含与分生组织相关的肌动蛋白7（ACT7）、“肌球蛋白XI尾部结合”RAB GTP酶C2A、一种与脂质体/胞间连丝相关的γ-分支1,3-β-葡聚糖酶，以及各种定位于细胞器和/或胞间连丝的蛋白质。这些结果与一个模型一致，即由肌球蛋白XI-k/1/2驱动的脂质体在F-肌动蛋白上运输，与其他细胞器短暂相互作用，并将多种货物输送到胞间连丝。
