A constitutive and drought-responsive mRNA undergoes long-distance transport in pear (Pyrus betulaefolia) phloem
A constitutive and drought-responsive mRNA undergoes long-distance transport in pear (Pyrus betulaefolia) phloem
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DOI：
10.1016/j.plantsci.2020.110419
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发表时间：
2020-04-01
期刊：
影响因子：
5.2
通讯作者：
Li, Wei
中科院分区：
文献类型：
--
作者：
Hao, Li;Zhang, Yi;Li, Wei
梨是世界上最重要的商业果树之一，广泛种植于温带地区。干旱胁迫严重限制了梨果实的产量和品质。杜梨（Pyrus betulaefolia Bunge）是我国北方地区常用的一种抗旱性优良的梨砧木，它能通过韧皮部移动mRNA等大分子物质的运输，使梨接穗对干旱胁迫做出快速反应。然而，干旱响应mRNA如何作为韧皮部移动信号发挥作用仍然未知。在此，我们使用RNA测序（RNA-seq）结合SNP分析来鉴定杜松中的移动的mRNA。我们研究了响应干旱胁迫的移动的mRNA，发现干旱条件下，几个不同品种的接穗嫁接到白桦砧木上后，一种名为PbDRM（P. betulaefoliaDROUGHT-RESPONSIVE MOBILE GENE）的新mRNA的丰度显著增加。另外，通过病毒诱导的基因沉默（VIGS）下调PbDRM，提高了杜宾的干旱敏感性。CAPS RT-PCR分析证实了PbDRM mRNA在微嫁接系统中从砧木移动到接穗。因此，PbDRM mRNA在梨干旱胁迫下充当韧皮部移动信号。
Pear is one of the most commercially important fruit trees worldwide and is widely cultivated in temperate zones. Drought stress can greatly limit pear fruit yield and quality. Pyrus betulaefolia Bunge, a drought-resistant pear rootstock that is commonly used in northern China, confers favourable characteristics to pear scions, allowing them to respond rapidly to drought stress via the transport of macromolecules such as phloem-mobile mRNAs. How drought-responsive mRNAs function as phloem-mobile signals remains unknown, however. Here, we used RNA sequencing (RNA-seq) combined with SNP analysis to identify mobile mRNAs in P. betulaefolia. We focused on mobile mRNAs that respond to drought stress and found that the abundance of a novel mRNA named PbDRM (P. betulaefoliaDROUGHT-RESPONSIVE MOBILE GENE) significantly increased in several different scion cultivars when they were grafted onto P. betulaefolia rootstock under drought conditions. In addition, down-regulating PbDRM by virus-induced gene silencing (VIGS) increased the drought sensitivity of P. betulaefolia. CAPS RT-PCR analysis confirmed that PbDRM mRNA moves from rootstock to scion in micrografting systems. Therefore, PbDRM mRNA acts as a phloem-mobile signal in pear under drought stress.