An Arabidopsis mutant named defective repression of OLE3::LUC 1 (drol1) was originally isolated as a mutant with defects in the repression of OLEOSIN3 (OLE3) after seed germination. In this study, we show that DROL1 is an Arabidopsis homolog of yeast DIB1, a subunit of U5 snRNP in the spliceosome. It is also part of a new subfamily that is specific to a certain class of eukaryotes. Comprehensive analysis of the intron splicing using RNA-Seq analysis of the drol1 mutants revealed that most of the minor introns with AT–AC dinucleotide termini had reduced levels of splicing. Only two nucleotide substitutions from AT–AC to GT–AG enabled AT–AC-type introns to be spliced in drol1 mutants. Forty-eight genes, including those having important roles in abiotic stress responses and cell proliferation, exhibited reduced splicing of AT–AC-type introns in the drol1 mutants. Additionally, drol1 mutant seedlings showed retarded growth, similar to that caused by the activation of abscisic acid signaling, possibly as a result of reduced AT–AC-type intron splicing in the endosomal Na⁺/H⁺ antiporters and plant-specific histone deacetylases. These results indicate that DROL1 is specifically involved in the splicing of minor introns with AT–AC termini, and that this plays an important role in plant growth and development.

中文翻译：

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剪接体中 U5 snRNP 的 DROL1 亚基是在拟南芥中剪接 AT-AC 型内含子所必需的

一种名为OLE3::LUC 1 ( drol1 )抑制缺陷的拟南芥突变体最初被分离为在种子萌发后具有OLEEOSIN3 ( OLE3 )抑制缺陷的突变体。在这项研究中，我们表明 DROL1 是酵母 DIB1的拟南芥同源物，酵母 DIB1 是剪接体中 U5 snRNP 的亚基。它也是特定于某类真核生物的新亚科的一部分。使用drol1 的RNA-Seq 分析综合分析内含子剪接突变体显示，大多数具有 AT-AC 二核苷酸末端的次要内含子的剪接水平降低。仅从 AT-AC 到 GT-AG 的两个核苷酸替换使 AT-AC 型内含子能够在drol1突变体中剪接。48 个基因，包括在非生物应激反应和细胞增殖中具有重要作用的基因，在drol1突变体中表现出 AT-AC 型内含子剪接减少。此外，drol1突变体幼苗表现出生长迟缓，类似于脱落酸信号激活引起的生长，可能是内体 Na ⁺ /H ^{+ 中}AT-AC 型内含子剪接减少的结果逆向转运蛋白和植物特异性组蛋白去乙酰化酶。这些结果表明 DROL1 特别参与了小内含子与 AT-AC 末端的剪接，这在植物生长发育中起着重要作用。