Transcriptome analysis of Idesia polycarpa Maxim. var vestita Diels fl owers during sex differentiation

Idesia polycarpa Maxim.var vestita Diels.is a dioecious tree species native to eastern Asia.There are diffi culties associated with distinguishing the sex of the plant at the seedling stage.In order to explore the mechanism of sex diff erentiation in fl ower development,we conducted the transcriptome profi les of male and female fl owers at early,metaphase and late developmental stages.Approximately 123,335 unigenes with a total length of 83,996 Mb and an average length of 168 bp were assembled.The unigenes were blasted into Nr,Nt,Pfam,KOG/COG,Swiss-prot,KEGG,GO databases.Homology analysis demonstrated that I.polycarpa and black cottonwood had the highest homology with the alignment of 92,871 sequences.This study identifi ed 80 groups of transcription factor families with a total of 1475 unigenes,mainly including MYB,WRKY,AP2 and bHLH transcription factor families.KEGG pathway analysis showed that the expression of numerous plant hormones(cytokinin,gibberellin and ethylene)and fl avonoid biosynthesis pathway were diff erent at various stages of female and male fl ower development.In addition,a number of unigenes associated with fl owering were identifi ed which were key genes associated with photoperiodic,vernalization,thermosensory,gibberellin,and autonomic pathways.The results show that I.polycarpa fl oral organ development was in accordance with the ABCDE model,in which the down-regulation of the B gene family might aff ect stamen fertility in late stages of female fl ower development.qRTPCR experiments validated that the expression patterns of 15 unigenes were consistent with those in RNA-seq results.The results highlight a central role for plant sex identifi cation in seedling production and a sex-determining mechanism for dioecious plants.In addition,the transcriptome data provided a theoretical basis for I.polycarpa genetic diversity analysis and molecular-assisted breeding.

Morphological and physiological differences in heteromorphic leaves of male and female Populus euphratica Oliv.

Leaf traits can directly reflect the adaptation strategies of plants to the environment.However,there is limited knowledge on the adaptation strategies of heteromorphic leaves of male and female Populus euphratica Oliv.in response to individual developmental stages(i.e.,diameter class)and canopy height changes.In this study,morphological and physiological properties of heteromorphic leaves of male and female P.euphratica were investigated.Results showed that both male and female P.euphratica exhibited increased leaf area(LA),leaf dry weight(LDW),leaf thickness(LT),net photosynthetic rate(P_(n)),transpiration rate(T_(r)),stomatal conductance(g_(s)),proline(Pro),and malondialdehyde(MDA)concentration,decreased leaf shape index(LI)and specific leaf area(SLA)with increasing diameter and canopy height.Leaf water potential(LWP)increased with increasing diameter,LWP decreased significantly with increasing canopy height in both sexes,and carbon isotope fraction(δ^(13)C)increased significantly with canopy height in both sexes,all of which showed obvious resistance characteristics.However,males showed greater LA,LT,P_(n),T_(r),and Pro than females at the same canopy height,and males showed significantly higher LA,SLA,LT,P_(n),T_(r),g_(s),and MDA,but lower LWP and δ_(1)3C than females at the same canopy height,suggesting that male P.euphratica have stronger photosynthetic and osmoregulatory abilities,and are sensitive to water deficiency.Moreover,difference between male and female P.euphratica is closely related to the increase in individual diameter class and canopy height.In summary,male plants showed higher stress tolerance than female plants,and differences in P_(n),g_(s),T_(r),Pro,MDA,δ_(13)C,and LWP between females and males were related to changes in leaf morphology,diameter class,and canopy height.The results of this study provide a theory for the differences in growth adaptation strategies during individual development of P.euphratica.