脂肪酰辅酶A还原酶（Fattyacyl‐CoAreductases,FAR）能够参与植物蜡质的合成，在植物生长发育中具有重要作用。最近，石河子大学刘峰和孙杰领衔的团队发现棉花中的一个FAR基因在叶片蜡质形成和增强植株抗旱性上具有重要作用。

研究人员对陆地棉的FAR基因进行了全基因组鉴定。共发现了10个GhFARs，形成5对同源基因（GhFAR2A-GhFAR3.4D），分布在6条染色体上。这10个GhFARs被分成两个亚家族。大多数GhFARs表现出组织特异性的表达模式，并且每对同源基因中至少有一对GhFAR在至少一个组织中相对高表达。其中，GhFAR3.1在叶片中高表达。利用VIGS技术沉默了GhFAR3.1的表达后，棉花叶片的总蜡至含量和相对含水量分别降低60%和13%以上，表明GhFAR3.1具有蜡质合成和抗失水的作用。干旱胁迫下，野生型植株叶片中蜡质的积累显著，而GhFAR3.1沉默植株叶片中蜡质的积累却不明显，导致GhFAR3.1沉默植株的保水能力降低，植株枯萎迅速。GhFAR3.1的沉默对处于GhFAR3.1上游的蜡质生物合成基因KAS、KCS和LACS的表达水平没有影响，但却降低了GhFAR3.1下游基因WSD的转录水平。

这些结果表明，叶片中的蜡质含量对棉花叶片保水性和抗旱性具有重要作用，GhFAR3.1是棉花叶片蜡质合成所必需的。

PlantDirect,07April

SilencingGhFAR3.1reduceswaxaccumulationincottonleavesandleadstoincreasedsusceptibilitytodroughtstress

Author

YajieLu,XinqiCheng,MengjiaoJia,XinyuZhang,FeiXue,YanjunLi,JieSun,FengLiu*

*:KeyLaboratoryofOasisEco-agriculture,CollegeofAgriculture,ShiheziUniversity,China

Abstract

Fattyacyl‐CoAreductases(FAR)areinvolvedinplantwaxsynthesisandplayimportantrolesinplantgrowthanddevelopment.However,littleinformationisavailableforcottonFARgenes.Inthisstudy,wecarriedoutagenome‐wideidentificationofFARgenesinUplandcotton(GossypiumhirsutumL.)andfound10GhFARsthatformfivepairsofhomoeologs(GhFAR2AtoGhFAR3.4D)distributedonsixchromosomes.The10GhFARswereseparatedintotwosubfamilies.MostGhFARsshowedtissue‐specificexpressionpatterns,andatleastoneGhFARofeachpairofhomoeologswasrelativelyhighlyexpressedinatleastoneofthetissuesinvestigated.GhFAR3.1washighlyexpressedinleaves.ThefunctionofGhFAR3.1inwaxaccumulationanddroughttolerancewasanalyzedusingvirus‐inducedgenesilencing(VIGS).SilencingGhFAR3.1reducedthetotalwaxcontentandrelativewatercontentofleavesbyover60%and13%,respectively,suggestingaroleofGhFAR3.1inwaxsynthesisandprotectionagainstwaterloss.Comparedtothewell‐wateredconditions,droughtstressinducedsignificantaccumulationofwaxinleavesofwild‐typeplantsbutnotinleavesofGhFAR3.1silencedplants,leadingtolesswaterholdingcapacityinGhFAR3.1silencedplantsandplantwilting.SilencingGhFAR3.1hadnoeffectontheexpressionlevelsofthewaxbiosynthesispathwaygenesKAS,KCS,andLACS(upstreamGhFAR3.1),butreducedthetranscriptlevelofitsdownstreamgeneWSD.Together,theseresultssuggestthatleafwaxcontentisimportantforwaterretentionanddroughttoleranceandthatGhFAR3.1isessentialforwaxsynthesisincottonleaves.TheseresultsalsoprovidethebasisforfurtherstudyonthemolecularregulationmechanismofGhFARsincottondevelopmentandsurfacelipidsynthesis.

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