Sex‐biased gene expression in dioecious garden asparagus (Asparagus officinalis)

Abstract

SummarySex chromosomes have evolved independently in phylogenetically diverse flowering plant lineages. The genes governing sex determination in dioecious species remain unknown, but theory predicts that the linkage of genes influencing male and female function will spur the origin and early evolution of sex chromosomes. For example, in an XY system, the origin of an active Y may be spurred by the linkage of female suppressing and male promoting genes.Garden asparagus (Asparagus officinalis) serves as a model for plant sex chromosome evolution, given that it has recently evolved an XX/XY sex chromosome system. In order to elucidate the molecular basis of gender differences and sex determination, we used RNAsequencing (RNA-Seq) to identify differentially expressed genes between female (XX), male (XY) and supermale (YY) individuals.We identified 570 differentially expressed genes, and showed that significantly more genes exhibited male-biased than female-biased expression in garden asparagus. In the context of anther development, we identified genes involved in pollen microspore and tapetum development that were specifically expressed in males and supermales.Comparative analysis of genes in the Arabidopsis thaliana, Zea mays and Oryza sativa anther development pathways shows that anther sterility in females probably occurs through interruption of tapetum development before microspore meiosis.

Slow evolution of sex‐biased genes in the reproductive tissue of the dioecious plant Salix viminalis

“…The level of sex‐biased gene expression found in the S. viminalis reproductive tissue is markedly lower than that in animal species (Jiang & Machado, ; Pointer et al., ), consistent with the significantly higher degree of sexual dimorphism in animal systems. On the other hand, we found a larger percentage of sex‐biased genes compared to several plant and algae species with low levels of sexual dimorphism (Harkess et al., ; Lipinska et al., ; Zemp et al., ). This is indicative of higher intersexual morphological differences in the S. viminalis reproductive tissue, which is consistent with previous descriptions of the structural differences between male and female catkins (Cronk et al., ).…”

Retrotransposon Proliferation Coincident with the Evolution of Dioecy inAsparagus

“…The transcriptome assembly and translation for A. officinalis was taken from Harkess et al (2015) (http://datadryad.org/resource/doi:10.5061/dryad.92c6010.5061/dryad.92c60). We generated leaf RNA-Seq for A. asparagoides by first isolating total RNA from mature leaf tissue using a Qiagen RNeasy Plant Mini kit.…”

Sex-oriented research on dioecious crops of Indian subcontinent: an updated review

“…Male asparagus plants are comparatively more disease resistant, have better yields and live longer than female plants (Kabir 1993) and also they do not produce seeds to create 'asparagus weed problem'. According to Harkess et al (2015), the chromosome number of diploid asparagus is 2n = 20 with x = 10. The females, males and supermales have XX, XY and YY sex chromosomes, respectively, and specifically males as well as supermales possess genes involved in pollen microspore and tapetum development.…”

“…and C. grandis (L.) Voigt), kiwifruit (Actinidia deliciosa var. deliciosa) and hemp (C. sativa L.) homogametic female (XX) and heterogametic male (XY) plants were documented (Ming et al 2007;Cherif et al 2013) but, a recent study also reported supermales (YY) in asparagus (Harkess et al 2015). In papaya (Carica papaya), which is trioecious in nature due to availability of three sex types (male, female and hermaphrodite), XY system is available and two distinct Y chromosomes viz.…”