拟南芥DA1-Related Protein2基因参与调控植物对盐胁迫的响应

Functional analysis of DA1-Related Protein 2 in Arabidopsis under salt stress

土壤盐渍化是目前农业生产面临的主要问题之一,同时种子萌发转绿作为植物幼苗形态建成的基础对盐胁迫最为敏感。本研究以Col-0、Ler野生型拟南芥和osr1短根突变体拟南芥为试验材料,通过图位克隆方法得到调控根生长的DAR2(DA1-Related Protein 2)基因。本研究利用RT-PCR方法,发现生长10 d的Col-0幼苗在200 mmol·L 1氯化钠条件下处理6 h和12 h,DAR2基因受盐胁迫诱导;200 mmol·L 1氯化钠处理后,组织化学染色结果显示,萌发1 d的根尖韧皮部和3 d的叶片pDAR2::GUS的表达上升,进一步表明DAR2基因受到盐胁迫的诱导。统计不同MS培养基[0(CK)、100 mmol·L 1氯化钠、150 mmol·L 1氯化钠、200 mmol·L 1氯化钠、150 mmol·L 1氯化钾、200 mmol·L 1甘露醇]上Col-0和dar2-3的萌发率和转绿率发现:随着氯化钠浓度的逐渐增大,突变体无论萌发还是转绿时间明显比野生型晚。在150 mmol·L 1氯化钾和200 mmol·L 1甘露醇培养条件下,萌发和转绿的时间也比野生型要晚。这些结果表明突变体在萌发和转绿期对盐胁迫的敏感性比野生型明显增强,进一步证明了突变体对盐胁迫的敏感性并不是对离子的特异响应。这些研究结果为深入了解逆境胁迫下植物早期生长发育的可塑性调控机制奠定了基础,同时也为通过生物技术改良作物抗逆性提供了理论依据。

Salt stress inhibits plant growth and development, resulting in low crop yield. Therefore, the mechanism of plant response to salt stress has received much attention in plant science research. Early development （including seed germination and greening） is not only critical for seedling establishment and subsequent plant growth and development, but is also more sensitive to salt stress. However, the molecular mechanisms underlying plant salt tolerance during this developmental stage has remained largely unknown. In this study, we identified a gene, DAR2 （DA1-Related Protein 2）, which regulated primary root growth by map-based cloning in Arabidopsis. We noted that DAR2 gene was induced by 200 mmol·L-1 NaCl in 10-day-old Col-0 seedlings. GUS staining showed that the expression ofpDAR2：：GUS was altered, suggesting that DAR2 gene was induced in root tip and leaf apex phloem. We counted the Col-0 and dar2-3 seed germination and greening rates in different MS medium -- 0 （CK）, 100 mmol·L-1 NaC1, 150 mmol·L-1 NaC1, 200 mmol·L-1 NaC1, 150 mmol·L-1 KC1 and 200 mmol·L-1 mannitol. These results showed that compared with the wild type, either seed germination or greening of dar2-3 mutant obviously delayed with gradual increase in NaC1 concentration. Under 150 mmol＇L-1 KC1 and 200 mmol.L-l mannitol treatments, dar2-3 mutant seed germination and greening delayed in relation to the wild type. Interestingly, the mutant exhibited increased sensitivity to NaC1, KC1 and mannitol treatments during seed germination and greening compared with the wild type. These results suggested that while DAR2 was effective in mediating plant response to general osmotic stress, it was not specific to ion stress in the early growth and development phase. Our findings provided novel insights into salt tolerance and enhanced crop resistance to salt stress.