Liu Hanmei, Yu Guiling, Wei Bin, Wang Yongbin, Zhang Junjie, Hu Yufeng, Liu Yinghong, Yu Guowu, Zhang Huaiyu, Huang Yubi
College of Life Science, Sichuan Agricultural University Ya'an, China.
Maize Research Institute, Sichuan Agricultural University Chengdu, China.
Front Plant Sci. 2015 Nov 20;6:1013. doi: 10.3389/fpls.2015.01013. eCollection 2015.
Starch is an important reserve of carbon and energy in plants, providing the majority of calories in the human diet and animal feed. Its synthesis is orchestrated by several key enzymes, and the amount and structure of starch, affecting crop yield and quality, are determined mainly by starch synthase (SS) activity. To date, five SS isoforms, including SSI-IV and Granule Bound Starch Synthase (GBSS) have been identified and their physiological functions have been well characterized. Here, we report the identification of a new SS isoform in maize, designated SSV. By searching sequenced genomes, SSV has been found in all green plants with conserved sequences and gene structures. Our phylogenetic analysis based on 780 base pairs has suggested that SSIV and SSV resulted from a gene duplication event, which may have occurred before the algae formation. An expression profile analysis of SSV in maize has indicated that ZmSSV is mainly transcribed in the kernel and ear leaf during the grain filling stage, which is partly similar to other SS isoforms. Therefore, it is likely that SSV may play an important role in starch biosynthesis. Subsequent analysis of SSV function may facilitate understanding the mechanism of starch granules formation, number and structure.
淀粉是植物中碳和能量的重要储备，为人类饮食和动物饲料提供了大部分热量。其合成由几种关键酶协调进行，而影响作物产量和品质的淀粉数量和结构主要由淀粉合酶（SS）活性决定。迄今为止，已鉴定出五种SS同工型，包括SSI-IV和颗粒结合淀粉合酶（GBSS），并且它们的生理功能已得到充分表征。在此，我们报告了在玉米中鉴定出一种新的SS同工型，命名为SSV。通过搜索已测序的基因组，在所有绿色植物中均发现了具有保守序列和基因结构的SSV。我们基于780个碱基对的系统发育分析表明，SSIV和SSV源于一次基因复制事件，该事件可能发生在藻类形成之前。对玉米中SSV的表达谱分析表明，ZmSSV在籽粒灌浆期主要在籽粒和穗叶中转录，这与其他SS同工型部分相似。因此，SSV可能在淀粉生物合成中发挥重要作用。随后对SSV功能的分析可能有助于理解淀粉颗粒形成、数量和结构的机制。
