Drought stress affects the growth and development of rice, resulting in severe loss in yield and quality. Ectopic expression of the bacterial RNA chaperone, cold shock protein (Csp), can improve rice drought tolerance. Archaeal TRAM (TRM2 and MiaB) proteins have similar structure and biochemical functions as bacterial Csp. Moreover, DNA replication, transcription and translation of archaea are more similar to those in eukaryotes. To test if archaeal RNA chaperones could confer plant drought tolerance, we selected two TRAM proteins, Mpsy_3066 and Mpsy_0643, from a cold-adaptive methanogenic archaea Methanolobus psychrophilus R15 to study. We overexpressed the TRAM proteins in rice and performed drought treatment at seedling and adult stage. The results showed that overexpression both TRAM proteins could significantly improve the tolerance of rice to drought stress. We further demonstrated in rice protoplasts that the TRAMs could abolish misfolded RNA secondary structure and improve translation efficiency, which might explain how TRAMs improve drought tolerance transgenic rice. Our work supports that ectopic expression of archaeal TRAMs effectively improve drought tolerance in rice.
干旱会直接影响水稻的生长发育，导致其产量和品质下降。在水稻中异源表达细菌RNA 分子伴侣Csp能够显著提高水稻的耐旱能力，并且不影响水稻的正常生长。古菌中也发现具有类似细菌分子伴侣Csp 功能的TRAM (TRM2 and MiaB) 蛋白，且古菌的DNA 复制、转录和翻译等过程与真核生物有着更为相似的调控方式，然而，古菌中RNA 分子伴侣蛋白能否调控植物耐旱能力还未见报道。我们选取了嗜冷甲烷古菌Methanolobus psychrophilus R15 中两个TRAM 蛋白在水稻中进行研究，发现在水稻中过量表达Mpsy_3066 和Mpsy_0643 两个TRAM 蛋白均能显著提高水稻苗期和成株期时对干旱胁迫的耐受能力。同时，我们在水稻原生质体中验证了TRAM 蛋白可以发挥其分子伴侣的功能消除RNA 的错误折叠对翻译的影响，这可能是TRAM 转基因植物发挥其耐旱能力的作用机制。该工作初步展示了异源表达古菌TRAMs 可以作为提高水稻耐旱能力的一种有效手段。.
Keywords: RNA chaperon; TRAM; archaea; drought stress; rice.