The Plant Cytoskeleton and Crosslinking Factors

Cytoskeleton exists in all eukaryotes and is involved in many significant cytobiological processes, especially the movements and developmental changes of plant cells. The cytoskeleton consists of microtubule (MT), microfilament (MF), and intermediate filament (IF). MT and MF are vital components of plant cytoskeleton. Crosslinking factor acts as a bridge between MF and MT. They play an important role in cellular life process and have always been a hot topic and key point in plant cytobiology, and the IF is a difficult point in this field. In this paper, the latest research on the cytoskeleton of plants is introduced, which focuses on the structure and dynamics of MT, MF, and IF, and summarizes the crosslinking factors between MT and MF. Also, the paper prospects the future research direction of plant cytoskeleton and the possible research hotspot, which provides a certain reference for people to continue to explore the function of plant cytoskeleton in the future.

The Effects of He-Ne Laser and Enhanced Ultraviolet-B Radiation on Proliferating-Cell Nuclear Antigen in Wheat Seedlings

The level of ultraviolet-B (UV-B) radiation on the Earth’s surface has increased due to depletion of the ozone layer. Here, we explored the effects of continuous wave He-Ne laser irradiation (632 nm, 5 mW·mm-2, 2 min·d-1) on proliferating-cell nuclear antigen (PCNA) damage repair function of wheat seedlings exposed to enhanced UV-B radiation (10.08 kJ&middotm-2·d-1) at the early growth stages. Wheat seedlings were irradiated with enhanced UV-B, He-Ne laser treatment or a combination of the two. We explored the transcripts of PCNA in each treatment group using RT-PCR. In addition, total proteins were extracted from the 7-day-old wheat leaves, analyzed by SDS-PAGE and identified by western blot. The results showed that the transcription of PCNA was weakened following UV-B radiation compared to the control. However, when seedlings were subjected to elevated UV-B-damaging radiation followed by He-Ne laser irradiation, the expression of PCNA was signifi-cantly higher than UV-B radiation alone. These results suggest that He-Ne laser has an active role in repairing the UV-B damaging effects. In order to further investigate the function of PCNA, dynamic arrangements of PCNA in wheat root-tip cells were observed with confocal laser scanning microscopy (CLSM). The PCNA was marked fluorescent dimming and strength weakened in en-hanced UV-B radiation (UV-B) compared with the control group (CK) during processing. It shows that PCNA may be involved in the separation of chromosomes.

Advances in the Application of Virus-Induced Gene Silencing in Plants

VIGS (Virus-induced gene silencing) can effectively silence target genes at the RNA level to investigate their functions. The virus vectors used for silencing are divided into three categories, DNA virus, RNA virus, and satellite virus, which can be used to silence the target genes in different species based on existing research. The genes used as markers for silencing system identification include PDS and PCNA. VIGS can be applied to some plants, in particular cash crops and fruit trees, to study their disease-resistance genes and genes related to growth and development to provide a basis for improving crop characteristics.

Application of VIGS system to explore the function of common wheat TaADF7

As an allohexaploid plant,common wheat has a complex gene structure,making it difficult to study its gene function.Virus-induced gene silencing(VIGS)is an important tool for the rapid analysis of plant gene function.In this study,the gene silencing system,namely,barley stripe mosaic virus(BSMV)-VIGS induced by BSMV was used to silence the wheat phytoene desaturase(TaPDS)and actin depolymerization factor(TaADF7)genes and determine the effect of gene silencing on wheat.TaPDS was used as an indicator gene to determine the feasibility of VIGS system,while TaADF7 was used as a test gene to determine its effect on wheat growth.Results showed that the leaves of tobacco and wheat were bleached by the mixture of pCaBS-α,pCaBS-β,and pCaBS-γ::TaPDS,indicating that the TaPDS gene was silenced,and the bleached leaves had physiological activity as determined by trypan blue staining.Therefore,the VIGS system was efficient and available.After the tobacco was treated with pCaBS-α,pCaBS-β,and pCaBS-γ::TaADF7,the viral suspension was obtained.The expression of TaADF7 gene was downregulated after wheat leaves were infected by friction,indicating that the expression of TaADF7 was silenced.Laser confocal scanning microscopy showed that the silencing of TaADF7 enhanced the fluorescence of microfilament skeleton in mesophyll protoplasts and significantly reduced the plant height.Results showed that TaADF7 affected cell division and plant growth by inhibiting microfilament depolymerization.In conclusion,the BSMV-VIGS system was used to silence wheat TaPDS and TaADF7 genes.Bleaching phenomenon was observed in wheat leaves after TaPDS silencing.After TaADF7 silencing,microfilaments in wheat mesophyll cells gathered into coarse bundles,which affected the dynamics of microfilaments and inhibited plant growth.

Different Doses of the Enhanced UV-B Radiation Effects on Wheat Somatic Cell Division

Being sessile, plants are continuously exposed to DNA-damaging agents presenting in the environment such as ultraviolet (UV). Sunlight acts as an energy source for photosynthetic plants;hence, avoidance of UV radiations (namely, UV-A, 315 - 400 nm;UV-B, 280 - 315 nm;and UV-C, 1 group: 4.05 kJ&#8226m-2&#8226d-1, B2 group: 10.08 kJ&#8226m-2&#8226d-1, B3 group: 7.05 kJ&#8226m-2&#8226d-1, B4 group: 23.02 kJ&#8226m-2&#8226d-1) treatment wheat, then, explored on the growth of wheat root and wheat root tip cell of chromosome aberration effect. In wheat, root-tip cells were observed with confocal laser scanning microscopy (CLSM), the results showed that low doses of B1 group (4.05 kJ&#8226m-2&#8226d-1) promoted the growth of wheat root and cell mitosis frequency. But high dose of B2 group (10.08 kJ&#8226m-2&#8226d-1), B3 group (17.05 kJ&#8226m-2&#8226d-1), B4 group (23.02 kJ&#8226m-2&#8226d-1) inhibited the growth of wheat root tip, and made crooked growth of wheat root, and inhibited the wheat root tip cell mitotic frequency and processed that induce root tip cells of wheat produce all kinds of aberration of chromosome in the interphase containing “multiple nucleoli nuclei”, “incomplete nuclei”, “long round nuclei”, “bean sprouts nucleus”. In mitosis M period contains “dissociative chromosome”, “chromosome bridge”, “adhesion chromosome”, “multi-bundle divide”, “nuclear anomalies”. After, high doses of enhanced UV-B radiation treatment, most of the cell cycle anomaly concentrated in mitosis interphase. In mitosis M period, with UV-B radiation dose enhanced chromosome aberration rate was on the rise and the aberration types also increasing.

拟南芥黏连蛋白RAD21对增强UV-B辐射后细胞分裂的响应

UV-B辐射对植物的影响体现在多个水平,其会引起植物DNA损伤,造成有丝分裂异常,最终影响植物的生长发育及生理生化过程。RAD21.3是黏连蛋白复合物的一个亚基,参与有丝分裂中染色体的分离。该研究以哥伦比亚生态型拟南芥(Arabidopsis thaliana)和atrad21.3突变体为材料,设置对照(CK)及UV-B处理组,对野生型(WT)、atrad21.3及过表达株系的根长、株高、抽薹时间和生理生化指标进行统计分析。利用碱性品红染色观察拟南芥根尖的有丝分裂现象,并统计畸变率。SPSS分析结果表明,UV-B处理后,WT UV-B和atrad21.3 CK的抽薹时间、株高及各项生理生化指标与WT CK相比无显著差异,但atrad21.3UV-B与之相比差异显著。通过烟草(Nicotianabenthamiana)的瞬时表达和亚细胞定位观察,发现RAD21.3集中在细胞核;进一步观察分裂期细胞发现落后染色体、染色体桥和游离染色体等异常现象。统计结果表明,与WT CK相比,WT UV-B和atrad21.3 CK的畸变率较高,但atrad21.3 UV-B的畸变率更高,表明RAD21.3可能响应UV-B辐射诱导的异常有丝分裂。

氮掺杂石墨烯量子点对拟南芥主根生长方向的影响

石墨烯量子点(GQDs)在电化学生物传感器、生物成像和生物医学等领域具有巨大的应用潜力,在公众和环境中的暴露程度也越来越高,近年来其生物安全性备受关注。截至目前,有关石墨烯量子点对植物生长发育影响的研究较少。该文从细胞和分子水平探究了氮掺杂石墨烯量子点(N-GQDs)处理对拟南芥(Arabidopsis thaliana)主根生长方向的影响。结果表明,N-GQDs能够被根摄取,并通过维管束运输。50-100 mg·L^(-1) N-GQDs处理可改变主根的生长方向,使其朝着远离培养基的方向发生弯曲。研究发现,N-GQDs处理导致根尖小柱细胞中淀粉粒的积累减少,生长素外排载体PIN3的表达量降低,小柱细胞中的PIN3重新定位到远离培养基一侧的细胞外侧膜(即朝向空气),促进根尖生长素的不对称分布,从而引发主根朝着远离培养基的方向弯曲生长,以避开较高浓度的N-GQDs环境。研究结果为进一步阐明N-GQDs处理改变根生长方向的机制提供了重要线索,同时也为N-GQDs的生物安全性评价提供参考依据。