Department of Plant Molecular Biology, University of Delhi South Campus, New Delhi, 110021, India.
Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India.
Planta. 2019 Dec 3;251(1):26. doi: 10.1007/s00425-019-03318-9.
Silencing of CI-sHsps by RNAi negatively affected the seed germination process and heat stress response of rice seedlings. Seed size of RNAi 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 (RNAi) rice lines. The major vegetative and reproductive attributes of the RNAi plants were comparable to the wild-type rice plants. Basal and acquired thermotolerance response of RNAi seedlings of rice was mildly affected. The seed length of RNAi rice plants was significantly reduced. The seed germination process was delayed and seed thermotolerance of RNAi was negatively affected than the non-transgenic seeds. We, thus, implicate that sHsp genes are critical in seedling thermotolerance and seed physiology.
通过 RNAi 沉默 CI-sHsps 会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，RNAi 的种子大小减小。小分子热休克蛋白（sHsps）是在各种环境和发育信号下普遍表达的无 ATP 依赖性伴侣蛋白。细胞质 sHsps 构成 sHsp 家族的主要组成部分。水稻细胞质 I 类（CI）-sHsps 由七个成员组成（Hsp16.9A、Hsp16.9B、Hsp16.9C、Hsp17.4、Hsp17.7、Hsp17.9A 和 Hsp18）。纯化的 OsHsp17.4 和 OsHsp17.9A 蛋白通过防止模型底物柠檬酸合酶形成大聚集体表现出伴侣活性。OsHsp16.9A 和 OsHsp17.4 显示核质定位，而 OsHsp17.9A 的定位则优先在核内。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应激后恢复过程中对各自的宿主表现出耐热性提高。设计了单发夹构建体以产生所有 CI-sHsp 沉默（RNAi）水稻系。RNAi 植物的主要营养和生殖属性与野生型水稻植物相当。RNAi 幼苗的基础和获得的耐热性反应受到轻微影响。RNAi 水稻植物的种子长度显著减小。种子萌发过程延迟，种子耐热性受到负面影响，不如非转基因种子。因此，我们认为 sHsp 基因在幼苗耐热性和种子生理学中至关重要。
