Chen Tianzi, Li Wenjuan, Hu Xuehong, Guo Jiaru, Liu Aimin, Zhang Baolong
Provincial Key Laboratory of Agrobiology, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China These authors contributed equally to this work.
Provincial Key Laboratory of Agrobiology, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China College of Agriculture, Nanjing Agricultural University, Nanjing 210095, China These authors contributed equally to this work.
Plant Cell Physiol. 2015 May;56(5):917-29. doi: 10.1093/pcp/pcv019. Epub 2015 Feb 4.
Drought stress negatively affects plant growth and limits plant productivity. Genes functioning in plant responses to drought stress are essential for the development of drought-tolerant crops. Here, we report that an R2R3-type MYB transcription factor gene in Gossypium barbadense, GbMYB5, confers drought tolerance in cotton and transgenic tobacco. Virus-induced gene silencing of GbMYB5 compromised the tolerance of cotton plantlets to drought stress and reduced the post-rewatering water recovery survival rate to 50% as compared with the 90% survival rate in the wild type (WT). Silencing GbMYB5 decreased proline content and antioxidant enzyme activities and increased malondialdehyde (MDA) content in cotton under drought stress. The expression levels of drought-inducible genes NCED3, RD22 and RD26 were not affected by the silencing of GbMYB5. However, GbMYB5-overexpressing tobacco lines displayed hypersensitivity to ABA and improved survival rates as well as reduced water loss rates under drought stress. Furthermore, stomatal size and the rate of opening of stomata were markedly decreased in transgenic tobacco. The overexpression of GbMYB5 enhanced the accumulation of proline and antioxidant enzymes while it reduced production of MDA in transgenic tobacco as compared with the WT under drought stress. The transcript levels of the antioxidant genes SOD, CAT and GST, polyamine biosynthesis genes ADC1 and SAMDC, the late embryogenesis abundant protein-encoding gene ERD10D and drought-responsive genes NCED3, BG and RD26 were generally higher in GbMYB5-overexpressing tobacco than in the WT under drought stress. Collectively, our data suggested that GbMYB5 was positively involved in the plant adaptive response to drought stress.
干旱胁迫对植物生长产生负面影响并限制植物生产力。在植物对干旱胁迫的响应中发挥作用的基因对于耐旱作物的培育至关重要。在此，我们报道了海岛棉中的一个R2R3型MYB转录因子基因GbMYB5，其赋予棉花和转基因烟草耐旱性。与野生型（WT）90%的复水后水分恢复存活率相比，通过病毒诱导的GbMYB5基因沉默损害了棉苗对干旱胁迫的耐受性，使复水后水分恢复存活率降至50%。在干旱胁迫下，沉默GbMYB5降低了棉花中的脯氨酸含量和抗氧化酶活性，并增加了丙二醛（MDA）含量。干旱诱导基因NCED3、RD22和RD26的表达水平不受GbMYB5沉默的影响。然而，过表达GbMYB5的烟草品系在干旱胁迫下对脱落酸表现出超敏感性，存活率提高且水分流失率降低。此外，转基因烟草中的气孔大小和气孔开放速率显著降低。与干旱胁迫下的野生型相比，过表达GbMYB5增强了转基因烟草中脯氨酸和抗氧化酶的积累，同时降低了MDA的产生。在干旱胁迫下，过表达GbMYB5的烟草中抗氧化基因SOD、CAT和GST、多胺生物合成基因ADC1和SAMDC、晚期胚胎发生丰富蛋白编码基因ERD10D以及干旱响应基因NCED3、BG和RD26的转录水平通常高于野生型。总体而言，我们的数据表明GbMYB5积极参与植物对干旱胁迫的适应性反应。
