Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Titre : Molecular and Physio-anatomical Responses of Populus under Drought Stress

Auteur : UMAIR AHMED

Grade : Doctoral Dissertation 2022

Université : Huazhong Agricultural University

Résumé partiel
Populus spp.consists of fast-growing forest tree species,and are extensively cultivated for paper,pulp and timber,and also have tremendous potential for biomass energy production.They contribute significantly in preventing soil-water loss or soil erosion,and in regularizing climate along with maintaining ecological stability.It is a diversified and wide spread genus,and has comprehensively been propagated.Most of the species growing in arid and semi-arid climatic zone are exposed to extended water deficit duration.We hypothesized that there would be a large set of parallel changes in the molecular,physiological and anatomical responses when plants exposed to drought stress ;these changes may enhance the capability of plants to survive and grow during drought periods.Therefore,in this study,we used hybrid poplar Populus tremula×Populus alba INRA no.717–1B4（hereafter referred to as poplar 717）as a model species to investigate the molecular,physiological and anatomical basis of woody plants involved in abiotic stress tolerance especially the drought stress,in order to better understand the mechanisms that enable plants to adapt to water stress and maintain growth,development and productivity during stress periods and to aid in for drought resistance.Moreover,we also investigated different Populus species to find out reliable set of reference genes（RGs）under different developmental tissues.The main results are as following:1.The quantitative real-time polymerase chain reaction（q RT-PCR）analysis revealed that the expression of flavonoid biosynthesis genes（Pt PAL,Pt4-CL,Pt CHS,Pt FLS-1,Pt F3H,Pt DFR,and Pt ANS）gradually increased in the leaves of hybrid poplar（P.tremula×P.alba）,corresponding to the drought stress duration.In addition,the activity and capacity of antioxidants have also increased,which is positively correlated with the increment of phenolic,flavonoid,anthocyanin,and carotenoid compounds under drought stress.As the drought stress prolonged,the level of reactive oxygen species such as hydrogen peroxide（H2O2）and singlet oxygen（O2-）too increased.The concentration of phytohormone salicylic acid（SA）also increased significantly in the stressed poplar717 leaves.2.With the use of transcriptome data generated from different Populus species under developmental and abiotic stress conditions,we describe a methodology to identify candidate RGs from high-throughput sequencing data available at public platforms.We retrieved the novel and reported RGs in transcriptome datasets of different Populus species,and selected 12 novel RGs and 6 reported RGs according to the coefficient of variation（CV）and fold change（FC）value of gene expression

Mots clés : Populus ;Drought stress ;Flavonoids biosynthesis ;Reference genes ;RNA-Seq ;Vascular tissues ;

Présentation (CNKI)