ZmBET5L1 inhibits primary root growth and decreases osmotic stress tolerance by mediating vesicle aggregation and tethering in maize

Abstract

Improving osmotic stress tolerance is critical to help crops to thrive and maintain high yields in adverse environments. Here, we characterized a core subunit of the transport protein particle (TRAPP) complex, ZmBET5L1, in maize using knowledge‐driven data mining and genome editing. We found that ZmBET5L1 can interact with TRAPP I complex subunits and act as a tethering factor to mediate vesicle aggregation and targeting from the endoplasmic reticulum to the Golgi apparatus. ZmBET5L1 knock‐out increased the primary root elongation rate under 20% polyethylene glycol‐simulated osmotic stress and the survival rate under drought stress compared to wild‐type seedlings. In addition, we found that ZmBET5L1 moderates PIN1 polar localization and auxin flow to maintain normal root growth. ZmBET5L1 knock‐out optimized auxin flow to the lateral side of the root and promoted its growth to generate a robust root, which may be related to improved osmotic stress tolerance. Together, these findings demonstrate that ZmBET5L1 inhibits primary root growth and decreases osmotic stress tolerance by regulating vesicle transport and auxin distribution. This study has improved our understanding of the role of tethering factors in response to abiotic stresses and identified desirable variants for breeding osmotic stress tolerance in maize.

Regulation of adaptive growth decisions via phosphorylation of the TRAPPII complex in Arabidopsis

“…One such example is ZmBet5L1 (Zhao et al, 2023), which encodes a core subunit of the TRAPPII complex (Kalde et al, 2019;Thellmann et al, 2010). Null alleles of ZmBet5L1 enhance root growth also in the absence of stress (Zhao et al, 2023). The TRAPPII complex has two distinct molecular functions: it acts as a tethering complex and as a Rab-GTPase guanine nucleotide exchange factor (Rab-GEF).…”

“…In the literature, there are few examples of null mutants that are associated with the TGN and that have a positive influence on growth. One such example is ZmBet5L1 (Zhao et al , 2023), which encodes a core subunit of the TRAPPII complex (Kalde et al , 2019; Thellmann et al , 2010). Null alleles of ZmBet5L1 enhance root growth also in the absence of stress (Zhao et al , 2023).…”