Biology subjects

Rahmati Ishka, M.

Publications and source records attributed to Rahmati Ishka, M..

4 recordsLinked to original sources

bioRxiv2024

Dissecting the genetic regulation of lateral root development in tomato under salt stress

Roots are the primary site for sensing salt, making them critical to understanding how plants adapt to salinity. Unraveling the genetic and molecular mechanisms that maintain root growth under salt stress is essential for developing resilient crops. Tomatoes are vulnerable to salinity, as over 50% of arable land is projected to become saline by 2050. While salt stress effects on tomato seed germination, shoot growth, and fruit yield are well-documented, the genetic basis of root development under salinity remains underexplored. Previous studies focused on physiological responses of roots in a narrow range of cultivated-tomatoes, overlooking the genetic diversity for salt resilience in wild-relatives like Solanum pimpinellifolium. Here, we investigated salt-induced changes in root system architecture (RSA) across a natural diversity panel of 220 wild- and 25 cultivated-tomato varieties. We identified tolerant accessions with different RSA strategies; prioritizing lateral root elongation versus emergence. To identify genes involved in specific aspects of lateral root development, an F1 hybrid was generated that exhibited both parents combined characteristics. An F2-segregating population was then used to identify four distinct subpopulations for Bulk Segregant Analysis (BSA). Simultaneously, we conducted Genome-Wide-Association Studies (GWAS) on root architecture of wild-tomato accessions under salt stress. By integrating the results of BSA and GWAS, we identified 22 candidates involved in the maintenance of root architecture. We utilized RNA-Seq to examine transcriptome reprogramming of the 22 genes in tomato accessions with contrasting lateral root responses. This approach resulted in the identification of 2 genes, AP2-like-ethylene-responsive transcription factor TOE3 and L-ascorbate peroxidase. Using exogenous ethylene, we demonstrated that root architecture exhibits plasticity, which benefits the plant by reducing Na+ accumulation. We profiled H2O2 waves across root systems of tomatoes, emphasizing the role of ROS in maintaining root system architecture under salt stress. These findings provide novel genetic targets for enhancing salt resilience in tomatoes, opening avenues for future research and breeding programs.

plant biology↗

bioRxiv2021

OPT3 plays a central role in both copper and iron homeostasis and signaling due to its ability to deliver copper as well as iron to the phloem in Arabidopsis

Copper and iron are essential micronutrients but are toxic when accumulating in cells in excess. Thus, their uptake by roots is tightly regulated. While plants sense and respond to local copper availability, the systemic regulation of copper uptake has not been documented. By contrast, both local and systemic control for iron uptake has been reported. Iron abundance in the phloem has been suggested to act systemically, regulating the expression of iron uptake genes in the root. Consistently, shoot-to-root iron signaling is disrupted in A. thaliana mutants lacking the phloem companion cell-localized iron transporter, AtOPT3: opt3 mutants overaccumulate iron in leaves while constitutively upregulating iron deficiency-responsive genes in roots. We report that AtOPT3 transports copper and mediates its delivery from source leaves to sinks including young leaves and developing embryos. Consequently, the opt3 mutant accumulates less copper in the phloem, is sensitive to copper deficiency, and mounts transcriptional copper deficiency response in roots. Copper rescues these defects. Notably, feeding the opt3 mutant with copper or iron via the phloem in leaves downregulates the expression of both copper and iron-deficiency marker genes in roots, suggesting that copper and iron can substitute each others function in the phloem in shoot-to-root communication. One-sentence summaryAtOPT3 loads copper and iron into the phloem companion cells, for subsequent distribution to sink tissues and systemic signaling of copper and iron deficiency.

plant biology↗

bioRxiv2020

Copper deficiency alters shoot architecture and reduces fertility of both gynoecium and androecium in Arabidopsis thaliana

Copper deficiency reduces plant growth, male fertility and seed set. The contribution of copper to female fertility and the underlying molecular aspects of copper deficiency-caused phenotypes are not well-known. We show that among copper deficiency-caused defects in Arabidopsis thaliana were the increased shoot branching, delayed flowering and senescence, and entirely abolished gynoecium fertility. The increased shoot branching of copper-deficient plants was rescued by the exogenous application of auxin or copper. The delayed flowering was associated with the decreased expression of the floral activator, FT. Copper deficiency also decreased the expression of senescence-associated genes, WRKY53 and SAG13, but increased the expression of SAG12. The reduced fertility of copper-deficient plants stemmed from multiple factors including the abnormal stigma papillae development, the abolished gynoecium fertility, and the failure of anthers to dehisce. The latter defect was associated with reduced lignification, the upregulation of copper microRNAs and the downregulation of their targets, laccases, implicated in lignin synthesis. Copper-deficient plants accumulated ROS in pollen and had reduced cytochrome c oxidase activity in leaves. This study opens new avenues for the investigation into the relationship between copper homeostasis, hormone-mediated shoot architecture, gynoecium fertility and copper deficiency-derived nutritional signals leading to the delay in flowering and senescence. HighlightCopper deficiency alters shoot architecture, delays flowering and senescence, and compromises fertility by altering stigma morphology, disrupting anther lignification and dehiscence, and pollen redox status in Arabidopsis thaliana.

plant biology↗

bioRxiv2019

YSL3-mediated copper distribution is required for fertility, grain yield, and size in Brachypodium.

Addressing the looming global food security crisis requires the development of high yielding crops. In this regard, the deficiency for the micronutrient copper in agricultural soils decreases grain yield and significantly impacts a globally important crop, wheat. In cereals, grain yield is determined by inflorescence architecture, flower fertility, grain size and weight. Whether copper is involved in these processes and how it is delivered to the reproductive organs is not well understood. We show that copper deficiency alters not only the grain set but also flower development in both wheat and its recognized model, Brachypodium distachyon, We then show that a brachypodium yellow-stripe-like 3 (YSL3) transporter localizes to the phloem and mediates copper delivery to flag leaves, anthers and pistils. Failure to deliver copper to these structures in the ysl3 CRISPR/Cas9 mutant results in delayed flowering, altered inflorescence architecture, reduced floret fertility, grain number, size, and weight. These defects are rescued by copper supplementation and are complemented by the YSL3 cDNA. This new knowledge will help to devise sustainable approaches for improving grain yield in regions where soil quality is a major obstacle for crop production.

plant biology↗