School of Agriculture, Food and Ecosystem Sciences - Research Publications
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ItemTowards Developing Drought-smart Soybeans(FRONTIERS MEDIA SA, 2021-10-06)Drought is one of the significant abiotic stresses threatening crop production worldwide. Soybean is a major legume crop with immense economic significance, but its production is highly dependent on optimum rainfall or abundant irrigation. Also, in dry periods, it may require supplemental irrigation for drought-susceptible soybean varieties. The effects of drought stress on soybean including osmotic adjustments, growth morphology and yield loss have been well studied. In addition, drought-resistant soybean cultivars have been investigated for revealing the mechanisms of tolerance and survival. Advanced high-throughput technologies have yielded remarkable phenotypic and genetic information for producing drought-tolerant soybean cultivars, either through molecular breeding or transgenic approaches. Further, transcriptomics and functional genomics have led to the characterisation of new genes or gene families controlling drought response. Interestingly, genetically modified drought-smart soybeans are just beginning to be released for field applications cultivation. In this review, we focus on breeding and genetic engineering approaches that have successfully led to the development of drought-tolerant soybeans for commercial use.
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ItemFeatured Cover(Wiley, 2021-08)
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ItemOverexpression of PIF4 affects plant morphology and accelerates reproductive phase transitions in soybean(WILEY, 2021-08)Abstract Phytochrome‐interacting factor 4 acts as a signalling hub for integrating multiple environmental cues like light and temperature. While the function of PIF4 in the model plant Arabidopsis has been studied, there is limited knowledge regarding the role of PIF4 in agronomically important legume crop soybean. Here, we employed a constitutive overexpression approach to functionally characterise a soybean PIF4 homolog, GmPIF4b in a determinate short‐day cultivar, Bragg. Multiple sequence alignment of seven soybean PIF4 homologs (GmPIF4a‐g) with Arabidopsis PIF4 revealed the presence of an active phytochrome‐binding (APB) domain in the N‐terminal region of six soybean PIF4 homologs. Cis‐elements related to plant hormone biosynthesis, stress response, meristem and endosperm gene expression were located in the promoter region of soybean PIF4s. Interestingly, transgenic soybean plants carrying 35s::GmPIF4b::polyA construct showed reduced plant height, reduced leaf surface area, decreased branching, early flowering and faster transition from full‐bloom flowering stage to full maturity stage without any decline in yield. Further, pod colour of transgenic soybean plants changed to dark brown, whereas wild‐type plants showed tan or light brown pod colour. Clear hilum was observed in seeds obtained from transgenic plants as opposed to the dark or black hilum of wild‐type seeds. Transcripts of soybean florigens GmFT2a and GmFT5a were also elevated in transgenic plants. Collectively, our results suggest that GmPIF4b overexpression could affect phenotypes related to plant morphology and reproductive stages in soybean, and can be used as a gene target for soybean improvement programmes to ensure future food security.
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ItemGenomic and molecular analysis of conserved and unique features of soybean PIF4(NATURE PORTFOLIO, 2018-08-22)Phytochrome-interacting factor 4 (PIF4) participates in light signaling by interacting with photoreceptors, phytochromes, and cryptochromes. Although well characterized in Arabidopsis, PIF4's role in crop plants is unknown. Here we performed the first integrated genomics, transcriptomics, and molecular characterization of PIF4 in soybean (Glycine max) plants. Fifteen identified Glycine max PIFs (GmPIFs) grouped into PIF3, PIF4, and PIF8 subfamilies based on their phylogenetic relationships. The GmPIF4 subfamily formed two distinct clades (GmPIF4 I and GmPIF4 II) with different amino acid sequences in the conserved bHLH region. Quantitative transcriptional analysis of soybean plants exposed to different photoperiods and temperatures indicated that all PIF4 I clade GmPIF4s conserved PIF4-like expression. Three out of four GmPIF4 transcripts of the GmPIF4 I clade increased at 35 °C compared to 25 °C under short day conditions. RNA sequencing of soybeans undergoing floral transition showed differential regulation of GmPIF4b, and ectopic GmPIF4b expression in wild type Arabidopsis resulted in an early flowering phenotype. Complementation of GmPIF4b in Arabidopsis pif4-101 mutants partially rescued the mutant phenotype. PIF4 protein levels peaked before dawn, and a GmPIF4b protein variant was observed in soybean plants treated at high temperatures.
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ItemAnalysis of the quinoa genome reveals conservation and divergence of the flowering pathways(SPRINGER HEIDELBERG, 2020-03)Quinoa (Chenopodium quinoa Willd.) is a grain crop grown in the Andes renowned as a highly nutritious plant exhibiting tolerance to abiotic stress such as drought, cold and high salinity. Quinoa grows across a range of latitudes corresponding to differing day lengths, suggesting regional adaptations of flowering regulation. Improved understanding and subsequent modification of the flowering process, including flowering time, ensuring high yields, is one of the key factors behind expansion of cultivation zones and goals of the crop improvement programs worldwide. However, our understanding of the molecular basis of flower initiation and development in quinoa is limited. Here, we use a computational approach to perform genome-wide identification and analysis of 611 orthologues of the Arabidopsis thaliana flowering genes. Conservation of the genes belonging to the photoperiod, gibberellin and autonomous pathways was observed, while orthologues of the key genes found in the vernalisation pathway (FRI, FLC) were absent from the quinoa genome. Our analysis indicated that on average each Arabidopsis flowering gene has two orthologous copies in quinoa. Several genes including orthologues of MIF1, FT and TSF were identified as homologue-rich genes in quinoa. We also identified 459 quinoa-specific genes uniquely expressed in the flower and/or meristem, with no known orthologues in other species. The genes identified provide a resource and framework for further studies of flowering in quinoa and related species. It will serve as valuable resource for plant biologists, crop physiologists and breeders to facilitate further research and establishment of modern breeding programs for quinoa.