Shunkang Zhou

The white-backed planthopper ( Sogatella furcifera ) serves as the vector for the southern rice black-streaked dwarf virus (SRBSDV), with varying transmission efficiencies across populations. This research identifies Wolbachia , a common insect symbiont, as a key facilitator in breaching the salivary gland barrier for SRBSDV, revealing a mechanism by which the virus exploits an insect symbiont for transmission. Through field and laboratory investigations, it was observed that high-transmission (HT) planthopper populations contained high levels of Wolbachia , while low-transmission (LT) populations had minimal titers. Experiments involving thoracic injections confirmed Wolbachia ’s specific role in infiltrating salivary glands, as SRBSDV was unable to colonize glands in Wolbachia -depleted insects despite being present systemically. Ultrastructural analysis showed Wolbachia enveloping SRBSDV particles within gland cells, further supported by molecular assays indicating a direct interaction between Wolbachia surface protein (WSP) and viral P8 capsid protein. Disruption of this interaction using anti-WSP antibodies reduced salivary gland viral load and transmission rates, underscoring its functional importance. These results contrast with Wolbachia ’s antiviral effects in mosquitoes, highlighting a context-dependent “hitchhiking” strategy for viral dissemination. The WSP–P8 interaction presents a specific target for inhibiting SRBSDV transmission without resorting to pesticides, proposing a symbiont-informed approach as a sustainable strategy against rice viral diseases.

Cucumber mosaic virus (CMV), a representative species of the genus Cucumvirus in the family Bromoviridae, is globally distributed and infects over 1200 monocot and dicot plants. 14-3-3 proteins serve as molecular adaptors that bind phosphorylated target proteins and play significant roles in multiple signaling pathways, including plant growth and development, hormone signaling, and responses to abiotic and biotic stimuli. Although an increasing body of evidence supports the prominent roles of 14-3-3 proteins in regulating plant immunity, their specific roles in plant responses to CMV infection remain unclear. Here, we demonstrate that 14-3-3λ and 14-3-3κ knockout Arabidopsis plants display enhanced tolerance to CMV infection, with significantly suppressed viral replication compared to wild-type (WT) plants. Additionally, we conducted transcriptomics analysis by comparing the CMV-infected 14-3-3λ 14-3-3κ (14-3-3λ/κ) double mutant to the WT using RNA-seq. The KEGG (Kyoto Encyclopedia of Genes and Genomes) enrichment and differentially expressed gene (DEG) results mainly suggest that plant hormone signaling, transcription factor activity, and the autophagy pathway are significantly involved in 14-3-3-mediated CMV tolerance in Arabidopsis. This study reveals new functions and potential molecular mechanisms of 14-3-3 proteins in regulating plant response to CMV infection and provides valuable insights into agricultural production.

Cadmium (Cd), an environmentally ubiquitous heavy metal, causes phytotoxic effects to plants even at low concentrations. Plants have evolved sophisticated methods to reduce Cd toxicity. However, the regulatory mechanisms of macroautophagy/autophagy in plant tolerance to Cd remain poorly elucidated. Here, we describe the link between autophagy and Cd response in Arabidopsis, demonstrating that the metallochaperone heavy metal‐associated isoprenylated plant protein 33 (HIPP33) acts as a cargo receptor to modulate the Cd response by facilitating autophagy‐mediated vacuolar sequestration of Cd. In Arabidopsis thaliana, Cd exposure activated autophagy pathway. Consistently, autophagy‐defective (atg) mutants displayed enhanced hypersensitivity with increased reactive oxygen species accumulation and considerably lower Cd concentrations in both roots and shoots. Moreover, we discovered that the core autophagy protein ATG8e associated with HIPP33 and recruited it for autophagic degradation in an AIM (ATG8‐interacting motif)‐dependent manner. Furthermore, purified HIPP33 protein directly bound with Cd in vitro. Accordingly, loss function of HIPP33 exhibited compromised Cd tolerance compared to wild‐type Arabidopsis. Collectively, our findings propose a novel regulatory mechanism where HIPP33 serves as a selective autophagy receptor to target Cd for autophagy‐dependent vacuolar sequestration in response to Cd stress, demonstrating the modulation of Cd detoxification by selective autophagy in plants.

In multicellular eukaryotes, autophagy is a conserved process that delivers cellular components to the vacuole or lysosome for recycling during development and stress responses. Induction of autophagy activates AUTOPHAGY-RELATED PROTEIN 1 (ATG1) and ATG13 to form a protein kinase complex that initiates autophagosome formation. However, the detailed molecular mechanism underlying the regulation of this protein complex in plants remains unclear. Here, we determined that in Arabidopsis thaliana, the regulatory proteins 14-3-3λ and 14-3-3κ redundantly modulate autophagy dynamics by facilitating SEVEN IN ABSENTIA OF ARABIDOPSIS THALIANA (SINAT)-mediated proteolysis of ATG13a and ATG13b. 14-3-3λ and 14-3-3κ directly interacted with SINATs and ATG13a/b in vitro and in vivo. Compared to wild-type (WT), the 14-3-3λ 14-3-3κ double mutant showed increased tolerance to nutrient starvation, delayed leaf senescence, and enhanced starvation-induced autophagic vesicles. Moreover, 14-3-3s were required for SINAT1-mediated ubiquitination and degradation of ATG13a. Consistent with their roles in ATG degradation, the 14-3-3λ 14-3-3κ double mutant accumulated higher levels of ATG1a/b/c and ATG13a/b than the WT upon nutrient deprivation. Furthermore, the specific association of 14-3-3s with phosphorylated ATG13a was crucial for ATG13a stability and formation of the ATG1–ATG13 complex. Thus, our findings demonstrate that 14-3-3λ and 14-3-3κ function as molecular adaptors to regulate autophagy by modulating the homeostasis of phosphorylated ATG13.

Southern rice black-streaked dwarf virus (SRBSDV), a Fijivirus in the Reoviridae family, is transmitted by the white-backed planthopper (Sogatella furcifera, WBPH), a long-distance migratory insect, and presents a serious threat to rice production in Asia. It was first discovered in China’s Guangdong Province in 2001 and has been endemic in the south of China and north of Vietnam for two decades, with serious outbreaks in 2009, 2010, and 2017. In this study, we evaluated the resistance of 10 dominant rice varieties from southern China, where the virus overwinters and accumulates as a source of early spring reinfection, against this virus by artificial inoculation. The results showed that in all tested varieties there was no immune resistance, but there were differences in the infection rate, with incidence rates from 21% to 90.7%, and in symptom severity, with plant weight loss from 66.71% to 91.20% and height loss from 34.1% to 65.06%. Additionally, and valuably, the virus titer and the insect vector virus acquisition potency from diseased plants were significantly different among the varieties: an over sixfold difference was determined between resistant and susceptible varieties, and there was a positive correlation between virus accumulation and insect vector virus acquisition. The results can provide a basis for the selection of rice varieties in southern China to reduce the damage of SRBSDV in this area and to minimize the reinfection source and epidemics of the virus in other rice-growing areas.