近年來全球暖化對於作物產量造成威脅，因此如何幫助水稻抵抗惡劣環境及提升作物產量皆現在重要的議題。水稻是世界上重要的糧食作物，其供應全球一半以上的人口食用，除此之外它亦是研究單子葉植物的模式植物，可提供我們研究其基因功能。根據我們先前的研究，除熱誘導外，水稻第一族小分子熱休克蛋白質中，OsHSP16.9A會在種子成熟時期表現及OsHSP18.0會受到重金屬銅或鎘誘導表現。為了更進一步了解它們的功能，我們建立OsHSP16.9A和OsHSP18.0持續性表現的轉殖株 (OsHSP16.9A-OE, OsHSP18.0-OE)，並建立抑制OsHSP16.9A、OsHSP18.0和sHSPs表現的轉殖株(Oshsp16.9A-RNAi, Oshsp18.0-RNAi, Osshsp-RNAi)。試驗結果發現OsHSP16.9A-OE種子和幼苗與OsHSP18.0-OE的幼苗皆具有對高溫的耐受性；Oshsp18.0-RNAi及Osshsp-RNAi不論在種子或幼苗對於高溫是敏感的。而利用基因表現或缺失的方式分析sHSPs是否參與在水稻的生長與發育中，結果發現Osshsp-RNAi植株其分櫱數會增加同時生長也較遲緩，因此從這個結果，我們推論sHSPs不只扮演著chaperone的功用保護失去活性的蛋白質外，同樣也參與在水稻的生長過程中。此外，我們也發現在Cu及Cd處理下，OsHSP18.0-OE植株比OsHSP16.9A-OE 和野生型植株對於重金屬逆境有較高的耐受性，而所受的氧化性傷害也是較少的，另OsHSP18.0-OE會降低銅誘導的細胞膜破損。這些結果都說明了OsHSP18.0-OE在水稻對抗重金屬逆境時扮演著重要的角色。 Recently global warming is threatening the crop yield. It becomes a critical issue to improve tolerance of rice to harsh environment as well as crop yield. Rice (Oryza sativa) is one of the most important crops in the world and feeds nearly 50% of the world’s population. Besides, it can be a model plant for providing insights into gene functions of monocotyledonous plants. Based on our previous data, we found that rice class I small heat shock proteins (sHSP-CIs) selectively expressed during seed maturation (OsHSP16.9A) and Cu or Cd treatment (OsHSP18.0). To further characterize physiological function of sHSP-CIs, we constructed two transgenic rice plants constitutively overexpressing OsHSP16.9A (OsHSP16.9A-OE) and OsHSP18.0 (OsHSP18.0-OE) and three transgenic rice plants repressing OsHSP16.9A (Oshsp16.9A-RNAi), OsHSP18.0 (Oshsp18.0-RNAi), and sHSPs (Osshsp-RNAi). Our results indicated that Oshsp16.9A-OE seeds and seedlings and Oshsp18.0-OE seedlings had higher thermotolerance than wild type during heat stress. Besides, Osshsp-RNAi plants were sensitive to heat stress. Interesting, gain- and loss-of-function analyses identified that sHSPs involved in rice growth and development. Osshsp-RNAi plants were shown increased in tiller number and delayed in growth. These results suggest that sHSPs can not only function as chaperone to protect denatured proteins but also involve in rice growth process. Furthermore, OsHSP18.0-OE plants showed more resistance than OsHSP16.9A-OE and wild-type plants under Cu and Cd treatment. Similarly, OsHSP18.0-OE plants were less oxidative damage. In addition, OsHSP18.0-OE plants reduced Cu-induced membrane damage. These results indicated OsHSP18.0-OE play important role in heavy metal stress.
