Browsing by Author "Jaskolowski, Aime"

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Editing cis-elements of OsPHO1;2 improved phosphate transport and yield in rice
(John Wiley & Sons, 2025) Maurya, Kanika; Mani, Balaji; Singh, Bhagat; Sirohi, Ujjwal; Jaskolowski, Aime; Sharma, Sandeep; Tatiparthi, Harsha Vardhan; Mangrauthia, Satendra Kumar; Pandey, Renu; Poirier, Yves; Giri, Jitender
Increasing grain yield is the primary goal of crop improvement, which is globally affected by the low availability of soil phosphate (Pi). Overexpressing Pi transporters to enhance Pi uptake often results in Pi toxicity and growth retardation. Despite advances in genetic engineering, targeting the cis-regulatory motifs of Pi transporters remains underexplored for understanding plant mechanisms and improving Pi status. Here, we demonstrate that the excision of the transcription inhibitor motif from the promoter of the Pi transporter OsPHO1;2 enhances its expression and increases root-to-shoot Pi transport, leading to improved grain yield. Through in silico and DNA-protein interaction studies, we show the role of the OsWRKY6 transcription factor in negatively regulating OsPHO1;2 expression by binding to the cis-regulatory element (W-box) present in its promoter. The oswrky6 knockout lines exhibit higher OsPHO1;2 expression and improved shoot Pi levels. Furthermore, we engineered the OsPHO1;2 promoter to precisely remove the W-box and enhance OsPHO1;2 expression. Phenotypic and physiological evaluations at the vegetative stage indicate that OsPHO1;2 promoter-edited (OsPHO1;2:PE) lines have increased shoot length, plant biomass and greater root-to-shoot Pi export under both low and normal P conditions. Notably, the 33P uptake assay reveals that OsPHO1;2:PE lines display enhanced root Pi uptake, supported by higher expression of root-associated Pi transporters (OsPHTs). An extensive agronomic assessment shows that OsPHO1;2:PE lines achieve increased seed and panicle numbers, thereby raising yield without affecting seed quality. Our findings provide valuable insights into the potential of promoter editing to improve Pi use and enhance crop yield.
Rice phosphate transporter reduces the low phosphate response through jasmonate signaling
(Oxford University Press, 2026) Mani, Balaji; Maurya, Kanika; Verma, Lokesh; Gupta, Priya; Kohli, Pawandeep Singh; Gupta, Gagan; Jaskolowski, Aime; Poirier, Yves; Giri, Jitender
Phosphorus (P) is an essential macronutrient for plant growth, and its deficiency severely limits crop productivity. The PHOSPHATE1 (PHO1) protein family, defined by an N-terminal SPX domain, four transmembrane (4TM) domains, and a C-terminal EXS domain, mediates phosphate (Pi) loading into the xylem for root-to-shoot transport. In rice, OsPHO1;2 is critical for Pi export, and loss-of-function mutants exhibit severe growth retardation and Pi deficiency symptoms despite sufficient external Pi. To dissect the functional contributions of PHO1 domains beyond Pi transport, we generated CRISPR/Cas9 rice lines expressing either the EXS domain containing part of the SPX domain (S-EXS) or the 4TM+EXS domains (T-EXS) of OsPHO1;2. Phenotypic analyses under Pi-sufficient and Pi-deficient conditions revealed that S-EXS lines displayed improved early growth compared to ospho1;2 mutants, despite similar shoot Pi levels. These plants exhibited reduced jasmonic acid accumulation and attenuated phosphate starvation responses, resembling wild-type hormone profiles. In contrast, T-EXS lines mirrored the growth defects of ospho1;2 mutants. Transcriptome profiling confirmed that defense and phosphate starvation pathways were less activated in S-EXS lines relative to mutants. However, both S-EXS and T-EXS lines retained seed development defects and reduced seed phosphorus content, consistent with ospho1;2 phenotypes. Heterozygous plants carrying one functional OsPHO1;2 allele exhibited normal growth and seed development, confirming the recessive nature of the mutation. Collectively, these findings demonstrate that the S-EXS domain of OsPHO1;2 promotes plant growth independently of Pi transport by modulating jasmonate signaling and suppressing phosphate starvation responses. This highlights a signaling role for PHO1 domains, offering new insights into Pi homeostasis and potential strategies for breeding Pi-efficient crops.