为探究干旱胁迫对大蒜(Allium sativum Linn.)叶绿素合成的影响，本研究基于大蒜转录组测序数据，筛选出响应干旱胁迫的大蒜叶绿素合成基因家族成员，利用实时荧光定量PCR（qRT-PCR）技术验证其表达情况后，采用生物信息学方法鉴定其序列属性。结果表明：从大蒜转录组数据中搜索得到的17个叶绿素合成基因家族中，筛选出6个积极响应干旱胁迫的大蒜叶绿素合成基因家族，即AsHEMA、AsHEMB、AsGSA、AsCHLD、AsCHLI和AsCAO。qRT-PCR和RNA-Seq结果显示：干旱胁迫6 d，AsHEMA、AsHEMB、AsGSA、AsCHLD、AsCHLI和AsCAO基因家族成员的表达量总体上显著增加。生物信息学分析结果显示：大蒜上述6个基因家族32个unigenes编码序列的氨基酸残基数为104~773，理论相对分子质量为11 978~84 411，理论等电点为pI 4.78至pI 9.86，不稳定指数为24.66~60.13，脂溶系数为80.04~104.59；除AsGSA家族外，其余5个家族成员的总平均亲水性为负值，即AsGSA家族成员为亲水蛋白，其余5个家族成员为疏水蛋白。保守基序分析结果表明：大蒜这6个叶绿素合成基因家族成员编码的氨基酸序列具有较高的保守性和相似性，其中，AsHEMA、AsGSA和AsCHLD家族高度保守；AsHEMB、AsCHLI和AsCAO家族保守性也较高，仅个别家族成员存在差异。进化树结果显示：大蒜同一叶绿素合成基因家族成员聚在一起，说明各基因家族的成员在进化上具有较高的保守性和相似性；AsHEMA、AsHEMB、AsCHLD、AsCHLI和AsCAO基因家族与单子叶植物小麦（Triticum aestivum Linn.）、石刁柏（Asparagus officinalis Linn.）和玉簪〔Hosta plantaginea (Lam.) Aschers.〕相关基因的同源性较高。上述研究结果显示：AsHEMA、AsHEMB、AsGSA、AsCHLD、AsCHLI和AsCAO基因家族的保守性和相似性较高，在大蒜响应干旱胁迫中发挥重要作用。

To explore the effect of drought stress on chlorophyll synthesis of Allium sativum Linn., members of chlorophyll synthesis gene families of A. sativum in response to drought stress were screened based on the transcriptome sequencing data of A. sativum, and their sequence properties were identified with  bioinformatics method after validation of expression levels by using realtime fluorescence quantification PCR (qRT-PCR). The results show that six chlorophyll synthesis gene families of A. sativum namely AsHEMA, AsHEMB, AsGSA, AsCHLD, AsCHLI, and AsCAO, which are actively responsive to drought stress, are selected from 17 chlorophyll synthesis gene families searched from the transcriptome data of A. sativum. The qRT-PCR and RNA-Seq results show that after 6 d of drought stress, the expression levels of members of AsHEMA, AsHEMB, AsGSA, AsCHLD, AsCHLI, and AsCAO gene families significantly increase in general. The bioinformatics analysis result shows that the numbers of amino acid residues of sequences encoded by 32 unigenes in above-mentioned six gene families of A. sativum are 104-773, their theoretical relative molecular mass are 11 978-84 411, their theoretical isoelectric points are from pI 4.78 to pI 9.86, their instability indexes are 24.66-60.13, and their aliphatic indexes are 80.04-104.59. Except for AsGSA family, grand average of hydropathicity of members of the other five families are negative, indicating that members of AsGSA family are of hydrophilic protein, while members of the other five families are of hydrophobic proteins. The conserved motif analysis result shows that the amino acid sequences encoded by members of these six chlorophyll synthesis gene families of A. sativum have high conservation and similarity, in which, AsHEMA, AsGSA, and AsCHLD families are highly conserved; AsHEMB, AsCHLI, and AsCAO families are also relatively well conserved, and there are differences only in a few family members. The result of phylogenetic tree shows that members of the same chlorophyll synthesis gene family are clustered together, which have high conservation and similarity in evolution; AsHEMA, AsHEMB, AsCHLD, AsCHLI, and AsCAO  gene families have high homology with related genes in monocotyledons Triticum aestivum Linn., Asparagus officinalis Linn., and Hosta plantaginea (Lam.) Aschers. It is suggested that  AsHEMA,  AsHEMB, AsGSA, AsCHLD, AsCHLI, and AsCAO gene families are highly conserved and similar, which play important roles in response to drought stress in A. sativum.