Cysteine protease activity comprises the majority of proteolytic activities in plants. They are involved in almost every facet of the plant’s development. Accumulating evidence indicates multiple roles of this protease type in response to biotic and abiotic stress. To understand the regulations and functions of cysteine protease in rice, its evolutionary and structural evidence was uncovered in this study. Using MEROPS, a peptidase database, the 74 rice cysteine proteases belonging to six families were queried. Each of these families represents distinct proteolytic enzyme; C1 is a papain-like protease, C2 is a calpain-2-type, C12 is an ubiquitinyl hydrolase-L1 enzyme, C13 is legumain, C14 is a caspase-1 type, and C15 is a pyroglutamyl peptidase 1 enzyme type. Evolutionary expansion attributed to gene duplication and diversification was particularly evident in C1 family which showed the highest number (n = 53) of members, most of which contained the highest number and most variable introns and motifs, whereas families C13, C14, and C15 had only a few members which all contained lesser number and variation of intron and motif. Out of 74 total cysteine protease gene members, 73 were globular proteins and 55 were predicted as stable proteins. Spatial expression assay of selected C1 members showed that LOC_Os01g73980 and LOC_Os05g01810 were highly expressed in the stem and leaves, while LOC_Os02g27030 was constitutively expressed in all tissues. The expression of LOC_Os01g73980 and LOC_Os05g01810 was also highly activated by salinity stress, while LOC_Os02g27030 was activated by both salinity and heat. LOC_Os05g01810 overexpression transgenic rice exhibited moderate tolerance to salinity stress, which provides interesting clues on biological functions of these genes in rice.

中文翻译：

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水稻中半胱氨酸蛋白酶基因的全基因组鉴定和分子表征

半胱氨酸蛋白酶活性包括植物中大多数蛋白水解活性。他们几乎参与了工厂发展的各个方面。越来越多的证据表明，这种蛋白酶对生物和非生物胁迫具有多种作用。为了了解水稻中半胱氨酸蛋白酶的调控和功能，本研究发现了其进化和结构证据。使用肽酶数据库MEROPS，查询了属于六个家族的74种水稻半胱氨酸蛋白酶。这些家族中的每一个都代表不同的蛋白水解酶。C1是木瓜蛋白酶样的蛋白酶，C2是钙蛋白酶-2型，C12是泛素水解酶-L1酶，C13是豆豆蛋白酶，C14是胱天蛋白酶-1型，并且C15是焦谷氨酰肽酶1酶型。ñ = 53）个成员，其中大多数包含最多的数目和最多的可变内含子和基序，而C13，C14和C15家族只有几个成员，它们全部包含较少的内含子和基序和变体。在74个总的半胱氨酸蛋白酶基因成员中，有73个是球状蛋白，有55个是稳定蛋白。选定的C1成员的空间表达分析表明，LOC_Os01g73980和LOC_Os05g01810在茎和叶中高表达，而LOC_Os02g27030在所有组织中组成性表达。盐度胁迫也高度激活了LOC_Os01g73980和LOC_Os05g01810的表达，而盐度和热都激活了LOC_Os02g27030。LOC_Os05g01810过表达转基因水稻对盐分胁迫表现出中等耐性，