Wang Nanbo, Zhao Jing, He Xiaoyan, Sun Hongyan, Zhang Guoping, Wu Feibo
Institute of Crop Science, Department of Agronomy, College of Agriculture and Biotechnology, Zijingang Campus, Zhejiang University, Hangzhou, 310058, People's Republic of China.
Jiangsu Co-Innovation Center for Modern Production Technology of Grain Crops, Yangzhou University, Yangzhou 225009, China, Yangzhou University, Yangzhou, 225009, China.
BMC Genomics. 2015 Jun 5;16(1):432. doi: 10.1186/s12864-015-1657-3.
Drought is one of major abiotic stresses constraining crop productivity worldwide. To adapt to drought stress, plants have evolved sophisticated defence mechanisms. Wild barley germplasm is a treasure trove of useful genes and offers rich sources of genetic variation for crop improvement. In this study, a proteome analysis was performed to identify the genetic resources and to understand the mechanisms of drought tolerance in plants that could result in high levels of tolerance to drought stress.
A greenhouse pot experiment was performed to compare proteomic characteristics of two contrasting Tibetan wild barley genotypes (drought-tolerant XZ5 and drought-sensitive XZ54) and cv. ZAU3, in response to drought stress at soil moisture content 10% (SMC10) and 4% (SMC4) and subsequently 2 days (R1) and 5 days (R2) of recovery. More than 1700 protein spots were identified that are involved in each gel, wherein 132, 92, 86, 242 spots in XZ5 and 261, 137, 156, 187 in XZ54 from SMC10, SMC4, R1 and R2 samples were differentially expressed by drought over the control, respectively. Thirty-eight drought-tolerance-associated proteins were identified using mass spectrometry and data bank analysis. These proteins were categorized mainly into photosynthesis, stress response, metabolic process, energy and amino-acid biosynthesis. Among them, 6 protein spots were exclusively expressed or up-regulated under drought stress in XZ5 but not in XZ54, including melanoma-associated antigen p97, type I chlorophyll a/b-binding protein b, glutathione S-transferase 1, ribulosebisphosphate carboxylase large chain. Moreover, type I chlorophyll a/b-binding protein b was specifically expressed in XZ5 (Spots A4, B1 and C3) but not in both of XZ54 and ZAU3. These proteins may play crucial roles in drought-tolerance in XZ5. Coding Sequences (CDS) of rbcL and Trx-M genes from XZ5, XZ54 and ZAU3 were cloned and sequenced. CDS length of rbcL and Trx-M was 1401 bp (the partial-length CDS region) and 528 bp (full-length CDS region), respectively, encoding 467 and 176 amino acids. Comparison of gene sequences among XZ5, XZ54 and ZAU3 revealed 5 and 2 SNPs for rbcL and Trx-M, respectively, with two 2 SNPs of missense mutation in the both genes.
Our findings highlight the significance of specific-proteins associated with drought tolerance, and verified the potential value of Tibetan wild barley in improving drought tolerance of barley as well as other cereal crops.
干旱是制约全球作物生产力的主要非生物胁迫之一。为了适应干旱胁迫，植物进化出了复杂的防御机制。野生大麦种质是有用基因的宝库，为作物改良提供了丰富的遗传变异来源。在本研究中，进行了蛋白质组分析，以鉴定遗传资源并了解植物耐旱机制，这些机制可能导致对干旱胁迫的高度耐受性。
进行了温室盆栽试验，以比较两种对比鲜明的西藏野生大麦基因型（耐旱的XZ5和干旱敏感的XZ54）和栽培品种ZAU3在土壤含水量10%（SMC10）和4%（SMC4）以及随后恢复2天（R1）和5天（R2）时对干旱胁迫的蛋白质组特征。每个凝胶中鉴定出1700多个蛋白质斑点，其中来自SMC10、SMC4、R1和R2样品的XZ5中的132、92、86、242个斑点和XZ54中的261、137、156、187个斑点在干旱条件下相对于对照有差异表达。通过质谱和数据库分析鉴定出38种与耐旱性相关的蛋白质。这些蛋白质主要分为光合作用、应激反应、代谢过程、能量和氨基酸生物合成。其中，6个蛋白质斑点在XZ5中仅在干旱胁迫下表达或上调，而在XZ54中没有，包括黑色素瘤相关抗原p97、I型叶绿素a/b结合蛋白b、谷胱甘肽S-转移酶1、核酮糖二磷酸羧化酶大亚基。此外，I型叶绿素a/b结合蛋白b在XZ5中特异性表达（斑点A4、B1和C3），而在XZ54和ZAU3中均未表达。这些蛋白质可能在XZ5的耐旱性中起关键作用。克隆并测序了XZ5、XZ54和ZAU3的rbcL和Trx-M基因的编码序列（CDS）。rbcL和Trx-M的CDS长度分别为1401 bp（部分长度CDS区域）和528 bp（全长CDS区域），分别编码467和176个氨基酸。XZ5、XZ54和ZAU3之间的基因序列比较显示，rbcL和Trx-M分别有5个和2个单核苷酸多态性（SNP），两个基因中均有两个错义突变的SNP。
我们的研究结果突出了与耐旱性相关的特定蛋白质的重要性，并验证了西藏野生大麦在提高大麦以及其他谷类作物耐旱性方面的潜在价值。
