Plant Cell Culture Technology Section, Nuclear Agriculture and Biotechnology Division, Bhabha Atomic Research Centre, Trombay, Mumbai, India.
Plant Biotechnol J. 2013 Oct;11(8):942-52. doi: 10.1111/pbi.12086. Epub 2013 Jun 10.
Water transport across cellular membranes is regulated by a family of water channel proteins known as aquaporins (AQPs). As most abiotic stresses like suboptimal temperatures, drought or salinity result in cellular dehydration, it is imperative to study the cause-effect relationship between AQPs and the cellular consequences of abiotic stress stimuli. Although plant cells have a high isoform diversity of AQPs, the individual and integrated roles of individual AQPs in optimal and suboptimal physiological conditions remain unclear. Herein, we have identified a plasma membrane intrinsic protein gene (MusaPIP1;2) from banana and characterized it by overexpression in transgenic banana plants. Cellular localization assay performed using MusaPIP1;2::GFP fusion protein indicated that MusaPIP1;2 translocated to plasma membrane in transformed banana cells. Transgenic banana plants overexpressing MusaPIP1;2 constitutively displayed better abiotic stress survival characteristics. The transgenic lines had lower malondialdehyde levels, elevated proline and relative water content and higher photosynthetic efficiency as compared to equivalent controls under different abiotic stress conditions. Greenhouse-maintained hardened transgenic plants showed faster recovery towards normal growth and development after cessation of abiotic stress stimuli, thereby underlining the importance of these plants in actual environmental conditions wherein the stress stimuli is often transient but severe. Further, transgenic plants where the overexpression of MusaPIP1;2 was made conditional by tagging it with a stress-inducible native dehydrin promoter also showed similar stress tolerance characteristics in in vitro and in vivo assays. Plants developed in this study could potentially enable banana cultivation in areas where adverse environmental conditions hitherto preclude commercial banana cultivation.
水跨细胞膜的运输是由一类被称为水通道蛋白（AQP）的水通道蛋白家族调节的。由于大多数非生物胁迫，如不适宜的温度、干旱或盐度，导致细胞脱水，因此研究 AQP 与非生物胁迫刺激的细胞后果之间的因果关系至关重要。尽管植物细胞具有高度的 AQP 同工型多样性，但单个和综合的 AQP 在最佳和次优生理条件下的作用仍不清楚。在此，我们从香蕉中鉴定出一种质膜内在蛋白基因（MusaPIP1;2），并通过在转基因香蕉植物中过表达对其进行了表征。使用 MusaPIP1;2::GFP 融合蛋白进行的细胞定位测定表明，MusaPIP1;2 易位到转化香蕉细胞的质膜。过表达 MusaPIP1;2 的转基因香蕉植物持续表现出更好的非生物胁迫生存特征。与在不同非生物胁迫条件下的相应对照相比，转基因系的丙二醛水平较低，脯氨酸和相对水含量升高，光合效率更高。在温室中保持硬化的转基因植物在停止非生物胁迫刺激后，向正常生长和发育的恢复速度更快，这突显出这些植物在实际环境条件下的重要性，在实际环境条件下，胁迫刺激通常是短暂但严重的。此外，通过标记带有胁迫诱导的天然脱水素启动子，使 MusaPIP1;2 的过表达成为条件性的转基因植物也在体外和体内试验中表现出类似的胁迫耐受性特征。在这项研究中开发的植物有可能使香蕉种植能够在以前因环境条件恶劣而无法进行商业香蕉种植的地区进行。
