ZmES genes encode peptides with structural homology to defensins and are specifically expressed in the female gametophyte of maize

Abstract

SummaryAll four members of a gene family, which are highly expressed in the cells of the female gametophyte (ZmES1±4: Zea mays embryo sac), were isolated from a cDNA library of maize egg cells. High expression of ZmES genes in the synergids around the micropylar region was detected in thin sections of maize ovaries. Single-cell RT±PCR analyses with the various cells of the female gametophyte con®rmed the expression in synergids and also showed expression in the egg cell and central cell, and low expression in the antipodals. The expression of the whole gene family is suppressed after fertilization of the embryo sac, and expression in two-cell or later embryo stages or other tissues of maize could not be detected. In order to investigate ZmES mRNA gradients in the highly polarized and vacuolized cells of the maize embryo sac, a whole-mount in situ protocol with isolated single cells was developed: as for total RNA, ZmES transcripts are uniformly distributed in the cytoplasm of egg cell, synergids and central cell. ZmES genes encode small, cysteine-rich proteins with an N-terminal signal peptide, probably for translocation into the embryo sac cell wall. The four ZmES proteins display high sequence identity with each other, and the proposed tertiary structure of the mature peptides is similar to that of plant and animal defensins. The function of ZmES1±4 during the fertilization process is discussed.

She's the boss: signaling in pollen tube reception

“…Small cysteine rich proteins (CRPs) have been implicated in many different phases of pollen-pistil interactions, from self-incompatibility early in pollination, to PT growth and guidance (reviewed in [8,9] been shown. However, CRPs were also identified to be highly expressed in maize synergid cells [11] and another short, secreted protein, ZmEA1, was shown to be involved in micropylar PT guidance in maize [12].…”

DiSUMO-like DSUL is required for nuclei positioning, cell specification and viability during female gametophyte maturation in maize

“…Cells of the maize embryo sac before fertilization were isolated according to Kranz et al (Kranz et al, 1991) and after fertilization according to Cordts et al (Cordts et al, 2001) with the exception that ears were kept on wet paper instead of MS medium. Tobacco (Nicotiana benthamiana) plants were grown at 22°C with 16 hours light and at 18°C in the dark with a relative air humidity of ~70%.…”

“…Hybridization, washing and exposure were performed according to the procedure described for DNA gel blots by the manufacturer (Roche). Single-cell (SC) RT-PCR analysis was performed as described (Cordts et al, 2001) with minor modifications. SC reverse transcription was performed using primers ZmDSULRev (5Ј-GCTGCCATCAATGATG-GAGCAG-3Ј), ZmSUMO1aRev (5Ј-GTCCCTCAGCAATGGCACAAG-3Ј) or ZmSUMO1bRev (5Ј-CAAGGAGCCAGAGCATCACAAG-3Ј) in addition to ZmGap2 (5Ј-GTAGCCCCACTCGTTGTCGTA-3Ј) for cDNA synthesis.…”

The Plant Peptidome: An Expanding Repertoire of Structural Features and Biological Functions

“…The ES family of maize encodes 61-to 68-amino acid peptides with eight Cys residues, and they are highly conserved with little variation at the C terminus. Secondary structure analysis of mature ES peptides predicts an a-helix and a triple-stranded antiparallel b-sheet (Cordts et al, 2001;Woriedh et al, 2015) (Figure 3). EMBRYO SURROUNDING FACTOR1 (ESF1) peptides were recently discovered in Arabidopsis as regulators of suspensor development and auxin distribution in early developing embryos (Costa et al, 2014).…”