Study Of Fruit Development Morphology,Drought Transcriptome And Functional Analysis Of HaHSFA1,HaNAC2 Genes On Haloxylon Ammodendron

Haloxylon ammodendron is a perennial shrub and belongs to Haloxylon Bunge(Chenopodiaceae).H.ammodendron is concentrated in northwest of China and plays an important role in the desert vegetation restoration.After a long period of evolution,H.ammodendorn has adapted to the harsh desert environment due to the efficient using of water and the ability of adversity resistance.The flowering period of H.ammodendron occurs from late April to mid-May,however,the ovary almost does not swell until late August or early September.Some researchers defined this phenomenon as "reproductive dormancy after flowering"(RDF),and demonstrated that photoperiod was the pivotal factor inducing H.ammodendron to represent RDF.But,it is necessary to describe the process of fruit development and deep research on the phenomenon.So,in the present study,we explored the phenomenon and characterized the morphology of H.ammodendron fruit development.Study on drought resistance in H.ammodendron carried out earlier and focused on ecology,morphology,anatomy,physiology biochemistry and molecular biology,but the researchs of transcriptomics were less.This study presented transcriptome analysis of H.ammodendron seedings treated by drought and rehydration sequenced by the next-sequencing platform of Illumina Hiseq 2500 and Miseq.We got 2 transcription factor genes HaHSFA1 and HaNAC2,and analyzed their biological function,and verified the transcriptome data by the expression patterns of 2 genes under drought stress.Main results are as follows:1.The RDF phenomenon of H.ammodendron was the slowly development of fruit and not significant in morphology.The result of anatomy demonstrated that it was the slowly development of embryo rather than long time dormancy of zygote or proembryo.The RDF phenomenon of H.ammodendron regulated by photoperiod was a typical photoperiodism and an effective reproductive strategy.And the long day delayed the reproductive development progress after flowering while the short day released it and accelerated the reproductive development progress.2.The transcriptome of drought and rehydration were profiled and compared,and a total of 420.14 Mb reads and 51.24 Gb bases were identified.Through quality control of raw data and de nove assembled,we got 41381 unigenes with an average length of 1539 nt,and N50 was 2115 nt.26154 unigenes(63.2%)were annotated by containing NR GO and KEGG databases,other 15227 unigenes(36.8%)could not be annotated successfully that might be new coding protein sequences and were expecting for further research.Gene expressions were significant difference in drought treatment and between assimilating branche and root:compared with control in material 1,2430 genes were up-regulated and 2278 genes were down-regulated in assimilating branche,4349 genes were up-regulated and 2550 genes were down-regulated in roots,but only 996 and 590 genes were up and down regulated respectively both in assimilating branche and root.And just 269 and 384 genes were up/down regulated both in material land 2.3.1 unigene(comp99842_c0_seq4)was annotated for heat shock transcription factor and up-regulated in roots under drought stress based on analysis of the transcriptome data.We isolated the gene and analyzed its structure.The predicted amino acid sequence analysis showed that:it contained a typical HSFA1 domain,so we defined it as HaHSFA1.Real-time quantitative-PCR analysis showed that expression levels of HaHSFA1 were difference in high/low temperature treatment and drought stress,and only up-regulated in root under drought stress.Transient expression of the HaHSFA1 protein in tobacco leaf cells showed that it was localized in cell nucleus.The HaNAC2 gene cloned into pCAMBIA1304 vector and then transferred into tobacco by Agrobacterium infection in this study.The experiments showed that expression of HaNAC2 in transgenic plants enhanced the tolerance of drought NaCl and low temperature.And the transcriptome data was verified to be reliable by expression patterns analysis of the 2 genes in drought treatment.In this study,the results of fruit development of H.ammodendron regulated by photoperiod will be helpful to accelerate seed production;the transcriptome data of drought and rehydration provide a large number of useful genetic informations for the research of plant resistance;the functional verification of HaHSFA1 and HaNAC2 have verified that the transcriptome data was reliable and showed the potential value for crop stress-resistant genetic engineering.