Structure and function of class III pistil-specific extensin-like protein in interspecific reproductive barriers

Abstract

Background The transmitting tissue of the style is the pathway for pollen tube growth to the ovules and has components that function in recognizing and discriminating appropriate pollen genotypes. In Nicotiana tabacum , the class III pistil extensin-like (PELPIII) arabinogalactan protein is essential for the inhibition of N. obtusifolia pollen tube growth. The transmitting tissue-specific (TTS) arabinogalactan protein amino acid sequence and expression pattern is similar to PELPIII, but it facilitates self-pollinated N. tabacum . The TTS and PELPIII arabinogalactan protein can be divided into the less conserved N-terminal (NTD) and the more conserved C-terminal (CTD) domains. This research tested whether the NTD is the key domain in determining PELPIII function in the inhibition of interspecific pollen tube growth. Three variant PELPIII gene constructs were produced where the PELPIII NTD was exchanged with the TTS NTD and a single amino acid change (cysteine to alanine) was introduced into the PELPIII NTD. The PELPIII variants of N. tabacum were tested for activity by measuring the inhibition N. obtusifolia pollen tube growth by using them to complement a 3’UTR RNAi transgenic line with reduced PELPIII mRNA. Results The RNAi N. tabacum line had reduced PELPIII mRNA accumulation and reduced inhibition of N. obtusifolia pollen tube growth, but had no effect on self-pollen tube growth or pollen tube growth of 12 other Nicotiana species. The NTD of PELPIII with either the PELPIII or TTS CTDs complemented the loss PELPIII activity in the RNAi transgenic line as measured by inhibition of N. obtusifolia pollen tube growth. The TTS NTD with the PELPIII CTD and a variant PELPIII with a cysteine to alanine mutation in its NTD failed to complement the loss of PELPIII activity and did not inhibit N. obtusifolia pollen tube growth. Conclusion The NTD is a key determinant in PELPIII’s function in regulating interspecific pollen tube growth and is a first step toward understanding the mechanism of how PELPIII NTD regulates pollen tube growth. Electronic supplementary material The online version of this article (10.1186/s12870-019-1728-8) contains supplementary material, which is available to authorized users.

Genomic imprinted genes in reciprocal hybrid endosperm of Brassica napus

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Functional and Transcriptome Analysis Reveal Specific Roles of Dimocarpus longan DlRan3A and DlRan3B in Root Hair Development, Reproductive Growth, and Stress Tolerance

“…Notably, extensins have been reported in reproductive development in some plants. For instance, the class III pistil-specific extensin-like proteins (PELPIIIs) of Nicotiana were associated with interspecific incompatibility, specific inhibition of pollen tube, and growth [ 37 , 38 ]. p DlRan3A -driven expression of DlRan3A led to abnormal fruits, larger seeds, a reduced seed setting rate, and increased seed weight, coinciding with increased and abnormal expression of PELP in PA_A.…”

Sweet Modifications Modulate Plant Development

“…Pistil-specific EXT-Like Proteins (PELP) make sure that the appropriate pollen type will germinate on compatible stigmas. This form of incompatibility prevents interspecies hybridization [ 178 , 181 , 182 ]. The concept of incompatibility can also apply to self-pollination.…”