Cytochrome b₆f complex is a thylakoid membrane-localized protein and catalyses the transfer of electrons from plastoquinol to plastocyanin in photosynthetic electron transport chain. In the present study, Cytochrome b₆ (KaCyt b₆) gene from Kappaphycus alvarezii (a red seaweed) was overexpressed in tobacco. A 935 base pair (bp) long KaCyt b₆ cDNA contained an open reading frame of 648 bp encoding a protein of 215 amino acids with an expected isoelectric point of 8.67 and a molecular mass of 24.37 kDa. The KaCyt b₆ gene was overexpressed in tobacco under control of CaMV35S promoter. The transgenic tobacco had higher electron transfer rate and photosynthetic yield over wild-type and vector control tobacco. The KaCyt b₆ tobacco also exhibited significantly higher photosynthetic gas exchange (P_N) and improved water use efficiency. The transgenic plants had higher ratio of P_N and intercellular CO₂. The KaCyt b₆ transgenic tobacco showed higher estimates of photosystem II quantum yield, higher activity of the water-splitting complex, PSII photochemistry, and photochemical quenching. The basal quantum yield of nonphotochemical processes in PSII was recorded lower in KaCyt b₆ tobacco. Transgenic tobacco contained higher contents of carotenoids and total chlorophyll and also had better ratios of chlorophyll a and b, and carotenoids and total chlorophyll contents hence improved photosynthetic efficiency and production of sugar and starch. The KaCyt b₆ transgenic plants performed superior under control and greenhouse conditions. To the best of our knowledge through literature survey, this is the first report on characterization of KaCyt b₆ gene from K. alvarezii for enhanced photosynthetic efficiency and growth in tobacco.

中文翻译：

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红海藻Kappaphycus alvarezii中跨膜蛋白KaCyt b6在转基因烟草中的异位表达增强了光合作用和生长。

细胞色素b ₆ f复合物是类囊体膜定位蛋白，可催化光合作用电子传输链中电子从质体喹诺酚向质体蓝蛋白的转移。在本研究中，来自烟草Kappaphycus alvarezii（一种红色海藻）的细胞色素b ₆（KaCyt b ₆）基因在烟草中过表达。一个长935个碱基对（bp）的KaCyt b ₆ cDNA包含一个648 bp的开放阅读框，编码215个氨基酸的蛋白，预期等电点为8.67，分子量为24.37 kDa。所述KaCyt b ₆该基因在CaMV35S启动子控制下在烟草中过表达。转基因烟草比野生型和载体对照烟草具有更高的电子传递速率和光合产量。所述KaCyt b ₆烟草也表现出显著较高的光合气体交换（P _Ñ）和水利用效率提高。转基因植株的P _N和细胞间CO ₂含量较高。所述KaCyt b ₆转基因烟草显示光系统II的量子产率的高的估计，该水分解复杂，PSII光化学，和光化学淬灭的更高的活性。在KaCyt b中记录到PSII中非光化学过程的基础量子产率较低₆烟草。转基因烟草中的类胡萝卜素和总叶绿素含量较高，叶绿素a和b的比例更好，类胡萝卜素和总叶绿素含量较高，因此提高了光合作用效率，提高了糖和淀粉的产量。所述KaCyt b _6种的转基因植物进行的控制和在温室条件下优异。为了最好通过文献调研我们所知，这是对的表征的第一份报告KaCyt b ₆从基因卡帕藻，增强光合效率和增长的烟草。