Silencing of CI-sHsps by RNAi negatively affected the seed germination process and heat stress response of rice seedlings. Seed size of RNAiCI-sHsp was reduced as compared to wild-type plants. Small heat shock proteins (sHsps) are the ATP-independent chaperones ubiquitously expressed in response to diverse environmental and developmental cues. Cytosolic sHsps constitute the major repertoire of sHsp family. Rice cytosolic class I (CI)-sHsps consists of seven members (Hsp16.9A, Hsp16.9B, Hsp16.9C, Hsp17.4, Hsp17.7, Hsp17.9A and Hsp18). Purified OsHsp17.4 and OsHsp17.9A proteins exhibited chaperone activity by preventing formation of large aggregates with model substrate citrate synthase. OsHsp16.9A and OsHsp17.4 showed nucleo-cytoplasmic localization, while the localization of OsHsp17.9A was preferentially in the nucleus. Transgenic tobacco plants expressing OsHsp17.4 and OsHsp17.9A proteins and Arabidopsis plants ectopically expressing OsHsp17.4 protein showed improved thermotolerance to the respective trans-hosts during the post-stress recovery process. Single hairpin construct was designed to generate all CI-sHsp silenced (RNAiCI-sHsp) rice lines. The major vegetative and reproductive attributes of the RNAiCI-sHsp plants were comparable to the wild-type rice plants. Basal and acquired thermotolerance response of RNAiCI-sHsp seedlings of rice was mildly affected. The seed length of RNAiCI-sHsp rice plants was significantly reduced. The seed germination process was delayed and seed thermotolerance of RNAiCI-sHsp was negatively affected than the non-transgenic seeds. We, thus, implicate that sHsp genes are critical in seedling thermotolerance and seed physiology.

中文翻译：

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I类小热休克蛋白的沉默影响水稻幼苗的种子相关属性和耐热性

RNAi 沉默 CI-sHsps 对水稻幼苗的种子萌发过程和热应激反应产生负面影响。与野生型植物相比，RNAiCI-sHsp 的种子大小减小。小热休克蛋白 (sHsps) 是独立于 ATP 的伴侣蛋白，普遍表达以响应不同的环境和发育线索。细胞溶质 sHsps 构成了 sHsp 家族的主要组成部分。水稻胞质 I 类 (CI)-sHsps 由七个成员（Hsp16.9A、Hsp16.9B、Hsp16.9C、Hsp17.4、Hsp17.7、Hsp17.9A 和 Hsp18）组成。纯化的 OsHsp17.4 和 OsHsp17.9A 蛋白通过防止与模型底物柠檬酸合酶形成大聚集体而表现出伴侣活性。OsHsp16.9A和OsHsp17.4显示出核质定位，而OsHsp17.9A优先定位在细胞核中。表达OsHsp17.4 和OsHsp17.9A 蛋白的转基因烟草植物和异位表达OsHsp17.4 蛋白的拟南芥植物在后应激恢复过程中对各自的反式宿主表现出改善的耐热性。单发夹构建体旨在生成所有 CI-sHsp 沉默 (RNAiCI-sHsp) 水稻品系。RNAiCI-sHsp 植物的主要营养和繁殖特性与野生型水稻植物相当。水稻 RNAiCI-sHsp 幼苗的基础和获得性耐热反应受到轻微影响。RNAiCI-sHsp 水稻植株的种子长度显着减少。与非转基因种子相比，种子发芽过程延迟并且种子对 RNAiCI-sHsp 的耐热性受到负面影响。因此，我们暗示 sHsp 基因在幼苗耐热性和种子生理学中至关重要。