Shen Jie, Xu Guoxin, Zheng Hui Qiong
Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Fenglin Road, 200032, Shanghai, China.
Protoplasma. 2015 Jan;252(1):173-80. doi: 10.1007/s00709-014-0669-1. Epub 2014 Jun 26.
The development of apoplastic barriers was studied in Zea mays seedling roots grown in hydroculture solution supplemented with 0-200 mM NaCl or 20% polyethylene glycol (PEG). Casparian bands in the endodermis of both NaCl- and PEG-treated roots were observed closer to the root tip in comparison with those of control roots, but the cell wall modifications in the endodermis and exodermis induced by salt and osmotic stresses differed. High salinity induced the formation of a multiseriate exodermis, which ranged from several cell layers to the entire cortex tissue but did not noticeably influence cell wall suberization in the endodermis. In contrast, osmotic stress accelerated suberization in both the endodermis and exodermis, but the exodermis induced by osmotic stress was limited to several cell layers in the outer cortex adjacent to the epidermis. The hydrostatic hydraulic conductivity (Lp) had decreased significantly after 1 day of PEG treatment, whereas in NaCl-treated roots, Lp decreased to a similar level after 5 days of treatment. Peroxidase activity in the roots increased significantly in response to NaCl and PEG treatments. These data indicate that salt stress and osmotic stress have different effects on the development of apoplastic barriers and water transport in Z. mays seedling roots.
研究了在添加0-200 mM NaCl或20%聚乙二醇（PEG）的水培溶液中生长的玉米幼苗根中质外体屏障的发育情况。与对照根相比，NaCl和PEG处理的根的内皮层中的凯氏带在根尖附近被观察到，但盐胁迫和渗透胁迫诱导的内皮层和外皮层中的细胞壁修饰有所不同。高盐度诱导形成多层外皮层，其范围从几层细胞到整个皮层组织，但对内皮层中的细胞壁栓质化没有明显影响。相反，渗透胁迫加速了内皮层和外皮层中的栓质化，但渗透胁迫诱导的外皮层仅限于表皮附近外皮层的几层细胞。PEG处理1天后，静水水力传导率（Lp）显著降低，而在NaCl处理的根中，处理5天后Lp降至相似水平。根中的过氧化物酶活性响应于NaCl和PEG处理而显著增加。这些数据表明，盐胁迫和渗透胁迫对玉米幼苗根中质外体屏障的发育和水分运输有不同的影响。
