RNAi-Mediated Knockdown of Calreticulin3a Impairs Pollen Tube Growth in <i>Petunia</i>
Pollen tube growth depends on several complex processes, including exo/endocytosis, cell wall biogenesis, intracellular transport, and cell signaling. Our previous results provided evidence that calreticulin (CRT)—a prominent calcium (Ca<sup>2+</sup>)-buffering molecular chaperone in the...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2022-04-01
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| Series: | International Journal of Molecular Sciences |
| Subjects: | |
| Online Access: | https://www.mdpi.com/1422-0067/23/9/4987 |
| Summary: | Pollen tube growth depends on several complex processes, including exo/endocytosis, cell wall biogenesis, intracellular transport, and cell signaling. Our previous results provided evidence that calreticulin (CRT)—a prominent calcium (Ca<sup>2+</sup>)-buffering molecular chaperone in the endoplasmic reticulum (ER) lumen—is involved in pollen tube formation and function. We previously cloned and characterized the <i>CRT</i> gene belonging to the <i>CRT1/</i>2 subgroup from <i>Petunia hybrida</i> (<i>PhCRT1/2</i>), and found that post-transcriptional silencing of <i>PhCRT1/2</i> expression strongly impaired pollen tube growth in vitro. Here, we report cloning of a new <i>PhCRT3a</i> homolog; we identified the full-length cDNA sequence and described its molecular characteristics and phylogenetic relationships to other plant <i>CRT3</i> genes. Using an RNA interference (RNAi) strategy, we found that knockdown of <i>PhCRT3a</i> gene expression caused numerous defects in the morphology and ultrastructure of cultivated pollen tubes, including disorganization of the actin cytoskeleton and loss of cytoplasmic zonation. Elongation of si<i>PhCRT3a</i> pollen tubes was disrupted, and some of them ruptured. Our present data provide the first evidence that <i>PhCRT3a</i> expression is required for normal pollen tube growth. Thus, we discuss relationships between diverse CRT isoforms in several interdependent processes driving the apical growth of the pollen tube, including actomyosin-dependent cytoplasmic streaming, organelle positioning, vesicle trafficking, and cell wall biogenesis. |
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| ISSN: | 1661-6596 1422-0067 |