Flexibility of resource allocation in a hermaphroditic-gynomonoecious herb through deployment of female and male resources in perfect flowers.

PREMISE OF THE STUDY: It has been hypothesized that two flower types permit flexible allocation of resources to female and male functions, yet empirical evidence for the sex-allocation hypothesis remains scarce in gynomonoecious species. To characterize resource allocation to pistillate and perfect flowers and allocation of perfect flowers between gynomonoecious and hermaphroditic individuals, we examined the flexibility and whether female-biased allocation increases with plant size in the hermaphroditic-gynomonoecious herb Eremurus anisopterus. METHODS: Frequency of gynomonoecious individuals, flower production, and plant size were investigated in different populations. Floral allocation was compared among the three flower types of E. anisopterus. KEY RESULTS: Frequency of gynomonoecious plants varied from 2-17% in nine populations. Only larger plants produced female flowers at the bottom of racemes. Both female and perfect flower production tended to increase proportionately with plant size in gynomonoecious individuals. Female flowers did not produce less biomass than perfect flowers from hermaphroditic or gynomonoecious plants. However, both female and perfect flowers from gynomonoecious individuals had lighter stamen mass, but larger pistil mass, than perfect flowers from hermaphrodites. CONCLUSIONS: Although the prediction of an increase in female flower number with plant size was not observed in E. anisopterus, the flexibility of sex allocation in gynomonoecious species was confirmed in that gynomonoecious individuals had a female-biased floral allocation compared to hermaphroditic individuals. Such comparisons of gynomonoecious to hermaphroditic individuals permit us to unveil a sexual adjustment strategy: flexibility of sexual investments within plants.

Whole-transcriptome sequence analysis of differentially expressed genes in Phormium tenax under drought stress.

Phormium tenax is a kind of drought resistant garden plant with its rich and colorful leaves. To clarify the molecular mechanism of drought resistance in Phormium tenax, transcriptome was sequenced by the Illumina sequencing technology under normal and drought stress, respectively. A large number of contigs, transcripts and unigenes were obtained. Among them, only 30,814 unigenes were annotated by comparing with the protein databases. A total of 4,380 genes were differentially expressed, 2,698 of which were finally annotated under drought stress. Differentially expression analysis was also performed upon drought treatment. In KEGG pathway, the mechanism of drought resistance in Phormium tenax was explained from three aspects of metabolism and signaling of hormones, osmotic adjustment and reactive oxygen species metabolism. These results are helpful to understand the drought tolerance mechanism of Phormium tenax and will provide a precious genetic resource for drought-resistant vegetation breeding and research.