MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China.
Planta. 2013 Apr;237(4):1135-47. doi: 10.1007/s00425-012-1834-4. Epub 2013 Jan 4.
Control of organ size by cell expansion and cell proliferation is a fundamental process during development, but the importance of BIG in this process is still poorly understood. Here, we report the isolation and characterization of a new allele mutant of BIG in Arabidopsis: big-j588. The mutant displayed small aerial organs that were characterized by reduced cell size in the epidermis and short roots with decreased cell numbers. The big-j588 axr1 double and big-j588 arf7 arf19 triple mutants displayed more severe defects in leaf expansion and root elongation than their parents, implying BIG is involved in auxin-dependent organ growth. Genetic analysis suggests that BIG may act synergistically with PIN1 to affect leaf growth. The PIN1 protein level decreased in both the root cells and the tips of leaf pavement cell lobes of big-j588. Further analysis showed that the auxin maxima in the roots and the leaves of big-j588 decreased. Therefore, we concluded that the small leaves and the short roots of big-j588 were associated with reduction of auxin maxima. Overall, our study suggested that BIG is required for Arabidopsis organ growth via auxin action.
细胞扩张和细胞增殖控制器官大小是发育过程中的一个基本过程，但 BIG 在这个过程中的重要性仍知之甚少。在这里，我们报道了拟南芥中 BIG 的一个新等位基因突变体 big-j588 的分离和鉴定。该突变体显示出小的地上器官，其特征是表皮细胞的细胞体积减小，根短且细胞数量减少。big-j588 axr1 双突变体和 big-j588 arf7 arf19 三突变体在叶片扩张和根伸长方面的缺陷比其亲本更为严重，表明 BIG 参与了依赖生长素的器官生长。遗传分析表明，BIG 可能与 PIN1 协同作用影响叶片生长。big-j588 中的根细胞和叶片铺砌细胞叶瓣的顶端的 PIN1 蛋白水平降低。进一步的分析表明，big-j588 中根和叶片中的生长素最大值降低。因此，我们得出结论，big-j588 的小叶片和短根与生长素最大值的减少有关。总的来说，我们的研究表明，BIG 通过生长素作用对拟南芥器官生长是必需的。
