Duman Zvi, Hadas-Brandwein Gal, Eliyahu Avi, Belausov Eduard, Abu-Abied Mohamad, Yeselson Yelena, Faigenboim Adi, Lichter Amnon, Irihimovitch Vered, Sadot Einat
The Institute of Plant Sciences, The Volcani Center, ARO, 68 HaMaccabim Road, Rishon LeZion 7528809, Israel.
The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 7610001, Israel.
Plants (Basel). 2020 Nov 3;9(11):1481. doi: 10.3390/plants9111481.
Dark-grown (etiolated) branches of many recalcitrant plant species root better than their green counterparts. Here it was hypothesized that changes in cell-wall properties and hormones occurring during etiolation contribute to rooting efficiency. Measurements of chlorophyll, carbohydrate and auxin contents, as well as tissue compression, histological analysis and gene-expression profiles were determined in etiolated and de-etiolated branches of the avocado rootstock VC801. Differences in chlorophyll content and tissue rigidity, and changes in xyloglucan and pectin in cambium and parenchyma cells were found. Interestingly, lignin and sugar contents were similar, suggesting that de-etiolated branches resemble the etiolated ones in this respect. Surprisingly, the branches that underwent short de-etiolation rooted better than the etiolated ones, and only a slight difference in IAA content between the two was observed. Gene-expression profiles revealed an increase in ethylene-responsive transcripts in the etiolated branches, which correlated with enrichment in xyloglucan hydrolases. In contrast, transcripts encoding pectin methylesterase and pectolyases were enriched in the de-etiolated branches. Taken together, it seems that the short de-etiolation period led to fine tuning of the conditions favoring adventitious root formation in terms of auxin-ethylene balance and cell-wall properties.
许多顽拗植物物种的黄化（黑暗生长）枝条比绿色枝条更容易生根。在此，我们假设黄化过程中细胞壁特性和激素的变化有助于提高生根效率。对鳄梨砧木VC801的黄化和脱黄化枝条进行了叶绿素、碳水化合物和生长素含量的测定，以及组织压缩、组织学分析和基因表达谱分析。结果发现，叶绿素含量和组织硬度存在差异，形成层和薄壁细胞中的木葡聚糖和果胶也发生了变化。有趣的是，木质素和糖含量相似，这表明脱黄化枝条在这方面与黄化枝条相似。令人惊讶的是，经历短期脱黄化的枝条比黄化枝条生根更好，两者之间仅观察到生长素含量的细微差异。基因表达谱显示，黄化枝条中乙烯反应转录本增加，这与木葡聚糖水解酶的富集相关。相反，编码果胶甲酯酶和果胶裂解酶的转录本在脱黄化枝条中富集。综上所述，短期脱黄化似乎在生长素-乙烯平衡和细胞壁特性方面对有利于不定根形成的条件进行了微调。
