Pollen tube growth is an essential step for successful plant reproduction. Vacuolar trafficking and dynamic organization are important for pollen tube growth; however, the key proteins involved in these processes are not well understood. Here, we report that the ADAPTOR PROTEIN-3 (AP-3) complex and its tonoplast cargo PROTEIN S-ACYL TRANSFERASE10 (PAT10) are critical for pollen tube growth in Arabidopsis (). AP-3 is a heterotetrameric protein complex consisting of four subunits, δ, β, µ, and σ. AP-3 regulates tonoplast targeting of several cargoes, such as PAT10. We show that functional loss of any of the four AP-3 subunits reduces plant fertility. In mutants, pollen development was normal but pollen tube growth was compromised, leading to reduced male transmission. Functional loss of caused a similar reduction in pollen tube growth, suggesting that the tonoplast association of PAT10 mediated by AP-3 is crucial for this process. Indeed, the Ca gradient during pollen tube growth was reduced significantly due to loss of function, consistent with the abnormal targeting of CALCINUERIN B-LIKE2 (CBL2) and CBL3, whose tonoplast association depends on PAT10. Furthermore, we show that the pollen tubes of mutants have vacuoles with simplified tubules and bulbous structures, indicating that AP-3 affects vacuolar organization. Our results demonstrate a role for AP-3 in plant reproduction and provide insights into the role of vacuoles in polarized cell growth.

The small GTPase Sar1, components of the COPII complex that mediates vesicular trafficking from ER to Golgi, participate in sporophytic and gametophytic control of pollen development in Arabidopsis, with different isoforms playing distinct or redundant roles.

Micron-sized holes distributed in the cross section of photonic crystal fibers allow the integration of the microfluidic analyte and fiber which makes it possible for rapid and effective chemical analysis. The innovation of this paper is that the polarization states of the fiber modes vary with the wavelength. The polarization directions of the two polarized modes are nearly 45 degrees with the horizontal direction at a certain wavelength, then the resonance wavelength will appear by a fiber Sagnac interferometer. The average sensitivity is up to −19040 nm/RIU as the refractive index of the microfluidic analyte varies from 1.33 to 1.37.

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SUMMARY Propagation of angiosperms mostly relies on sexual reproduction, in which gametophytic development is a pre‐requisite. Male gametophytic development requires both gametophytic and sporophytic factors, most importantly early secretion and late programmed cell death of the tapetum. In addition to transcriptional factors, proteins at endomembrane compartments, such as receptor‐like kinases and vacuolar proteases, control tapetal function. The cellular machinery that regulates their distribution is beginning to be revealed. We report here that ADP‐RIBOSYLATION FACTOR‐A1s (ArfA1s) are critical for tapetum‐controlled pollen development. All six ArfA1s in the Arabidopsis genome are expressed during anther development, among which ArfA1b is specific to the tapetum and developing microspores. Although the ArfA1b loss‐of‐function mutant showed no pollen defects, probably due to redundancy, interference with ArfA1s by a dominant negative approach in the tapetum resulted in tapetal dysfunction and pollen abortion. We further showed that all six ArfA1s are associated with the Golgi and the trans‐Golgi network/early endosome, suggesting that they have roles in regulating post‐Golgi trafficking to the plasma membrane or to vacuoles. Indeed, we demonstrated that the expression of ArfA1bDN interfered with the targeting of proteins critical for tapetal development. The results presented here demonstrate a key role of ArfA1s in tapetum‐controlled pollen development by mediating protein targeting through post‐Golgi trafficking routes.