College of Life sciences, Jilin Agricultural University, 2888 Xincheng Street, Changchun City, 130000, People's Republic of China.
Jilin Engineering Vocational College, Siping City, Jilin, 136000, People's Republic of China.
BMC Plant Biol. 2021 Jan 15;21(1):45. doi: 10.1186/s12870-020-02805-6.
'Regal Splendour' (Hosta variety) is famous for its multi-color leaves, which are useful resources for exploring chloroplast development and color changes. The expressions of chlorophyll biosynthesis-related genes (HrHEMA, HrPOR and HrCAO) in Hosta have been demonstrated to be associated with leaf color. Herein, we isolated, sequenced, and analyzed HrHEMA, HrPOR and HrCAO genes. Subcellular localization was also performed to determine the location of the corresponding enzymes. After plasmid construction, virus-induced gene silencing (VIGS) was carried out to reduce the expressions of those genes. In addition, HrHEMA-, HrPOR- and HrCAO-overexpressing tobacco plants were made to verify the genes function. Changes of transgenic tobacco were recorded under 2000 lx, 6000 lx and 10,000 lx light intensity. Additionally, the contents of enzyme 5-aminolevulinic acid (5-ALA), porphobilinogen (PBG), chlorophyll a and b (Chla and Chlb), carotenoid (Cxc), superoxide dismutase (SOD), peroxidase (POD), malondialdehyde (MDA), proline (Pro) and catalase (CAT) under different light intensities were evaluated.
The silencing of HrHEMA, HrPOR and HrCAO genes can induce leaf yellowing and chloroplast structure changes in Hosta. Specifically, leaves of Hosta with HrCAO silencing were the most affected, while those with HrPOR silencing were the least affected. Moreover, all three genes in tobacco were highly expressed, whereas no expression was detected in wild-type (WT). However, the sensitivities of the three genes to different light intensities were different. The highest expression level of HrHEMA and HrPOR was detected under 10,000 lx of illumination, while HrCAO showed the highest expression level under 6000 lx. Lastly, the 5-ALA, Chla, Cxc, SOD, POD, MDA, Pro and CAT contents in different transgenic tobaccos changed significantly under different light intensities.
The overexpression of these three genes in tobacco enhanced photosynthesis by accumulating chlorophyll content, but the influential level varied under different light intensities. Furthermore, HrHEMA-, HrPOR- and HrCAO- overexpressing in tobacco can enhance the antioxidant capacity of plants to cope with stress under higher light intensity. However, under lower light intensity, the antioxidant capacity was declined in HrHEMA-, HrPOR- and HrCAO- overexpressing tobaccos.
“Regal Splendour”（玉簪品种）因其多色叶片而闻名，这些叶片是探索叶绿体发育和颜色变化的有用资源。已证明玉簪中叶绿素生物合成相关基因（HrHEMA、HrPOR 和 HrCAO）的表达与叶片颜色有关。在此，我们分离、测序并分析了 HrHEMA、HrPOR 和 HrCAO 基因。还进行了亚细胞定位以确定相应酶的位置。构建质粒后，进行病毒诱导的基因沉默（VIGS）以降低这些基因的表达。此外，还构建了 HrHEMA、HrPOR 和 HrCAO 过表达的烟草植物，以验证这些基因的功能。在 2000 lx、6000 lx 和 10000 lx 光照强度下记录转基因烟草的变化。此外，还评估了不同光照强度下酶 5-氨基乙酰丙酸（5-ALA）、卟胆原（PBG）、叶绿素 a 和 b（Chla 和 Chlb）、类胡萝卜素（Cxc）、超氧化物歧化酶（SOD）、过氧化物酶（POD）、丙二醛（MDA）、脯氨酸（Pro）和过氧化氢酶（CAT）的含量。
沉默 HrHEMA、HrPOR 和 HrCAO 基因可诱导玉簪叶片黄化和叶绿体结构改变。具体来说，HrCAO 沉默的玉簪叶片受影响最大，而 HrPOR 沉默的玉簪叶片受影响最小。此外，烟草中这三个基因的表达均高度上调，而野生型（WT）中则未检测到表达。然而，这三个基因对不同光照强度的敏感性不同。HrHEMA 和 HrPOR 的表达水平在 10000 lx 的光照下最高，而 HrCAO 的表达水平在 6000 lx 时最高。最后，不同光照强度下，三种基因在不同转基因烟草中的 5-ALA、Chla、Cxc、SOD、POD、MDA、Pro 和 CAT 含量均发生显著变化。
这些基因在烟草中的过表达通过积累叶绿素含量来增强光合作用，但在不同光照强度下的影响程度不同。此外，在烟草中过表达 HrHEMA、HrPOR 和 HrCAO 可以增强植物的抗氧化能力，以应对高光强下的胁迫。然而，在低光强下，HrHEMA、HrPOR 和 HrCAO 过表达烟草的抗氧化能力下降。
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