Genome Editing for Plasmodesmal Biology

Abstract

Plasmodesmata (PD) are cytoplasmic canals that facilitate intercellular communication and molecular exchange between adjacent plant cells. PD-associated proteins are considered as one of the foremost factors in regulating PD function that is critical for plant development and stress responses. Although its potential to be used for crop engineering is enormous, our understanding of PD biology was relatively limited to model plants, demanding further studies in crop systems. Recently developed genome editing techniques such as Clustered Regularly Interspaced Short Palindromic Repeats/CRISPR associate protein (CRISPR/Cas) might confer powerful approaches to dissect the molecular function of PD components and to engineer elite crops. Here, we assess several aspects of PD functioning to underline and highlight the potential applications of CRISPR/Cas that provide new insight into PD biology and crop improvement.

Keywords: CRISPR/Cas; crop engineering; genome editing; plant stress; plasmodesmata.

FIGURE 1

Major genome editing techniques for crop improvement through plasmodesmal engineering. Many PD-associated proteins are involved in a variety of environmental stresses (abiotic and biotic stresses). Depending on the impact on stress mechanism, particular PD-associated proteins can be classified as negative (A) or positive (B) regulators. PD-associated proteins that negatively regulate stress tolerance in plants (summarized in panel A) can be targeted using genome editing tools such as simple knockout by CRISPR/Cas, base editor, prime editor, gene targeting and directed evolution tools (C). On the other hand, PD-associated proteins that positively regulate stress tolerance in plants (summarized in panel B) may provide the easiest way to overexpress them by transgenic approach. Targeting PD-associated proteins by genome editing or transgenically possess potential avenues to improve crop quality and productivity. ER, Endoplasmic reticulum; PM, plasma membrane; BAM1 and 2, barely any meristem 1 and 2; GLU I and III, β-1,3-glucanase class I and III; ANK1, ankyrin repeat-containing protein; SYTA, Synaptotagmin A; NbHIPP26, Nicotiana benthamiana heavy metal-associated isoprenylated plant protein; NbEXPA1, N. benthamiana α-expansin 1; PDLP1, 2, 3, 5, and 7, Plasmodesmata-located protein 1, 2, 3, 5, and 7; PATL3 and 6, patellin 3 and 6; CML41, calmodulin-like protein 41; REM1.3, Remorin 1.3; CRK2, Cys-rich receptor-like kinase 2; QSK1, Qian Shou kinase 1; DHyPRP1, double hybrid proline-rich protein 1; LYM2, lysin motif domain-containing glycosylphosphatidylinositol-anchored protein 2; IMK2, inflorescence meristem kinase 2; RGP2, reversibly glycosylated polypeptide 2.