Biology subjects

Ai, G.

Publications and source records attributed to Ai, G..

5 recordsLinked to original sources

bioRxiv2023

Plant immunity activated and suppressed by a conserved effector protein family in mirid bug Riptortus pedestris

Riptortus pedestris (Fabricius) a major soybean pest migrates into soybean fields during pod filling stage resulting in a leaf and stem staygreen while pods without beans syndrome. Given the agricultural importance of this species and the lack of characterized HAMP from piercing-sucking insects we performed a large scale of screening by expression of 87 R. pedestris salivary proteins with signal peptides in Nicotiana benthamiana obtaining a candidate HAMP RPH1. RPH1 activated a series of PTI responses including ROS burst upregulation of defense marker genes such as PR1 WRKY7 WRKY8 Acre31 and CYP71D20 MAPK activation and biosynthesis of phytohormones in plants. RPH1 significantly enhances soybean resistance against R. pedestris feeding. PRR coreceptors BAK1 and SOBIR1 were required for RPH1-induced PTI responses. Remarkably RPH1 homologs were widely distributed in herbivorous insects and majority of homologs from selected species induced cell death or ROS. Thus our results demonstrated that RPH1 is a conserved HAMP within chewing and piercing-sucking insects. We also discovered that R. pedestris evolved four paralogs to overcome the plant immunity triggered by RPH1. This study filled a major gap of HAMP identification from piercing-sucking insect and also deciphered a novel evasion strategy of plant immunity exploited by herbivorous insects. One sentence summaryRiptortus pedestris RPH1, a conserved HAMP in herbivores, activates a variety of PTI responses in plants. To couterdefense, R. pedestris evolved four paralogs to suppress RPH1-induced PTI responses. The author(s) responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (https://academic.oup.com/plcell/pages/General-Instructions) is: Ai Xia (xia@njau.edu.edu).

plant biology↗

bioRxiv2022

A pair of NLRs coordinately modulates NRC3-mediated ETI responses to facilitate age-dependent immunity

Two NLRs (Nucleotide-binding and Leucine-rich repeat Receptors) adjacent to each other on a locus, termed as paired NLRs, may act separately for effector recognition and subsequent signaling activation to mediate effector-triggered immunity (ETI) in many plants. However, it is largely unknown about their distribution and functions in Solanaceae species, in which NLR-Hs (Helpers NLR REQUIRED FOR CELL DEATHs) have been extensively studied. Here, we identified paired NLRs in Solanaceae species and found they harbor paired NLRs ranging from 6 to 100, which are significantly negatively correlated with the numbers of NLR-Hs. N. benthamiana has six paired NLRs, among which silencing of NRCX exhibits phenotypes of dwarfism and accelerated senescence. Importantly, NRCX-silencing phenotypes could be restored by simultaneously silencing its head-to-head NLR pair, thus we named it as NRCY. NRCX/Y pair is specific in Solanaceae species. NRCY contains non-canonical walker B and MHD motifs, but could not induce autoactive cell death in N. benthamiana. Instead of that, silencing NRCY impaired cell death triggered by Sw5b-Nsm and NRC3D480V, indicating NRCY is also an NLR modulator like NRCX. Furthermore, NRCX suppression of Sw5b-Nsm and NRC3-mediated cell death is dependent on NRCY. Remarkably, we found that NRCX and NRCY expressions were induced during plant senescence, while NRCY was induced more than NRCX. Accordingly, the plant resistance was stronger during maturation, indicated NRCX/Y might be involved in age-dependent resistance. Our study reveals one of the paired NLRs coordinately regulates ETI to facilitate age-dependent immunity.

plant biology↗

bioRxiv2022

Boosting transformation in wheat by BBM-WUS

Agrobacterium-mediated transformation is a cost-effective and convenient way to introduce foreign genetic elements to plants. However, only limited protocols successfully generates transgenic plants with fielder, a spring wheat variety. Wheat transformation method with higher efficiency and without genotype restriction is heavily demanded. Here, a heat-shock protocol, independent of Japan Tobacco had been established. Transgenic plants can be obtained from immature embryo within only 60 days by this protocol. Morphogenic regulators Baby boom and Wuschel (BBM-WUS) was proved to promote transformation efficiency for five to six times in wheat when co-infiltrated with agrobacterium containing target construct. Notably, half of the transformants are BBM-WUS free and moreover, the BBM-WUS containing plants could be picked by florescent marker that was co-expressed with BBM-WUS. In conclusion, we managed to establish a new wheat transformation protocol with shorter duration than published protocol.

plant biology↗

bioRxiv2020

Genome-wide association study reveals the genetic architecture of 27 yield-related traits in tomato

Tomato (Solanum lycopersicum) is a highly valuable vegetable crop and yield is one of the most important traits. Uncovering the genetic architecture of yield-related traits in tomato is critical for the management of vegetative and reproductive development, thereby enhancing yield. Here we perform a comprehensive genome-wide association study for 27 yield-related traits in tomato. A total of 239 significant associations corresponding to 129 loci, harboring many reported and novel genes related to vegetative and reproductive development, were identified, and these loci explained an average of [~]8.8% of the phenotypic variance. A total of 51 loci associated with 25 traits have been under selection, especially during tomato improvement. Furthermore, a candidate gene, SlALMT15 that encodes an aluminum-activated malate transporter, was functionally characterized and shown to act as a pivotal regulator of leaf stomata formation through increasing photosynthesis and drought resistance. This study provides valuable information for tomato genetic research and breeding.

plant biology↗

bioRxiv2019

Prediction and Characterization of RXLR Effectors in Pythium Species

Being widely existed in oomycetes, the RXLR effector features conserved RXLR-dEER motifs in its N terminal. Every known Phytophthora or Hyaloperonospora pathogen harbors hundreds of RXLRs. In Pythium species, however, none of the RXLR effectors has been characterized yet. Here, we developed a stringent method for de novo identification of RXLRs and characterized 359 putative RXLR effectors from nine tested Pythium species. Phylogenetic analysis revealed a single superfamily formed by all oomycetous RXLRs, suggesting they descent from a common ancestor. RXLR effectors from Pythium and Phytophthora species exhibited similar sequence features, protein structures and genome locations. In particular, the mosquito biological agent P. guiyangense contains a significantly larger RXLR repertoire than the other eight Pythium species examined, which may result from gene duplication and genome rearrangement events as indicated by synteny analysis. Expression pattern analysis of RXLR-encoding genes in the plant pathogen P. ultimum detected transcripts from the vast majority of predicted RXLRs with some of them being induced at infection stages. One such RXLRs showed necrosis-inducing activity. Furthermore, all predicted RXLRs were cloned from two biocontrol agents P. oligandrum and P. periplocum. Three of them were found to encode effectors inducing defense response in Nicotiana benthamiana. Taken together, our findings represent the first complete synopsis of Pythium RXLR effectors, which provides critical clues on their evolutionary patterns as well as the mechanisms of their interactions with diverse hosts. Author summaryPathogens from the Pythium genus are widespread across multiple ecological niches. Most of them are soilborne plant pathogens whereas others cause infectious diseases in mammals. Some Pythium species can be used as biocontrol agents for plant diseases or mosquito management. Despite that phylogenetically close oomycete pathogens secrete RXLR effectors to enable infection, no RXLR protein was previously characterized in any Pythium species. Here we developed a stringent method to predict Pythium RXLR effectors and compared them with known RXLRs from other species. All oomycetous RXLRs form a huge superfamily, which indicates they may share a common ancestor. Our sequence analysis results suggest that the expansion of RXLR repertoire results from gene duplication and genome recombination events. We further demonstrated that most predicted Pythium RXLRs can be transcribed and some of them encode effectors exhibiting pathogenic or defense-inducing activities. This work expands our understanding of RXLR evolution in oomycetes in general, and provides novel insights into the molecular interactions between Pythium pathogens and their diverse hosts.

microbiology↗