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Sugarcane (Saccharum spp.) is an important food, fodder and energy crop in India. Its production and productivity are mainly constrained due to water deficit stress during different growth stages. Of the root system architecture traits, deep rooting helps plants to avoid drought-induced stress by foraging moisture from deeper layers of soil. Hence, in this study, a novel drought-responsive DEEPER ROOTING 1 (DRO1) gene cloned from drought-tolerant Erianthus arundinaceus was characterized. The open reading frame of this gene is 765 bp that encodes for a single polypeptide of 254 amino acids. In silico analysis of DRO1 protein using bioinformatics tools revealed its size of 28.91 kDa with theoretical pI 5.39, instability index 67.57, aliphatic index 69.92 and GRAVY of -0.86. Subcellular localization by LocTree3 tool suggested that DRO1 protein expression is localized in the nucleus. The phylogenetic tree exhibited that DRO1 from Erianthus arundinaceus is closely associated with that of Sorghum bicolor and Triticum aestivum. Protein interaction network analysis showed DRO1 association with WOX11, which promotes the development of crown roots and ARL1 (Adventitious rootless1) required for adventitious root formation. Quantitative gene expression analysis indicated that the DRO1 gene is differentially upregulated in root tissue of E. arundinaceus and Saccharum spp. commercial hybrid under water deficit stress conditions. EaDRO1 gene can be a novel source for developing drought stress tolerant genotypes through genetic engineering approach.

Abstract Sugarcane root system comprises of superficial sett roots as well as deeply-penetrating shoot borne roots (SBR) with latter being the permanent root system. In sugarcane, the healthy SBR contributes to a better crop yield and it also helps to produce multiple ratoon crops after the harvest. There is a dearth of in-depth knowledge on SBR system architecture and its functional role in modern day commercial hybrids. A comprehensive phenotypic, anatomical and whole transcriptome profiling, conducted between the commercial sugarcane hybrids and a wild germplasm Erianthus, found a developmental delay in both initiation and establishment of the SBR in commercial hybrid compared to Erianthus. The SBR system in Erianthus proved to be an extensive drought-adaptive root system architecture that significantly contributes to drought tolerance. On the other hand, SBRs in the commercial hybrids showed an irreversible collapse and damage of the root cells under drought stress. The outcomes from the comparative analysis of the transcriptome data showed a significant upregulation of the genes that regulate important stress signalling pathways viz., sugar, calcium, hormone signalling and phenylpropanoid biosynthesis in the SBRs of Erianthus. It was found that through these key signalling pathways, Erianthus SBRs triggered the downstream signalling cascade to impart physiological responses like osmoprotection, modification of the cell walls, detoxification of reactive oxygen species, expression of drought responsive transcription factors, maintenance of cell stability and lateral root development. The current study forms a basis for further exploration of the Shoot Borne Root system as a valuable breeding target to develop drought tolerant sugarcane genotypes.

A comprehensive analysis of the transcript levels of genes involved in sucrose accumulation is fundamental for the assessment of the function of each enzyme and regulatory mechanism of sucrose metabolism in sugarcane. The expression profiles of genes encoding sucrose phosphate synthase (SPS), sucrose phosphate phosphatase (SPP), soluble acid invertase (SAI), cell wall invertase (CWI), pyrophosphate fructose-6-phosphate phosphotransferase (PFP), fructokinase (FK), hexokinase (HK) and ADP-glucose pyrophosphorylase (ADP-G) in sugarcane was examined using RT-PCR. Different modes of gene expression were observed for each gene revealing the complexity of sucrose metabolizing pathway in sugarcane. Transcript levels of SPS, SPP, SAI, CWI, Sucrose transporter (SUT1 and SUT4) were found to be differentially regulated between high and low sugar commercial sugarcane hybrids. But no definite pattern of expression of these genes was observed in different Saccharum spp. Similarly PFP, FK and HK were also differentially expressed in commercial sugarcane hybrids as compared to different Saccharum spp suggesting the role of these enzymes in the regulation of sucrose metabolism in sugarcane. Expression of Sucrose synthase (SuSy) was uniform in both high and low sugar genotypes of Saccharum spp. and commercial sugarcane hybrids whereas expression of ADP-G was found only in high sugar Saccharum officinarum clone.

Abstract Erianthus arundinaceus [Retzius] Jeswiet, a wild relative of sugarcane has a high biomass production potential and a reservoir of many genes for superior agronomic traits and tolerance to biotic and abiotic stresses. A comparative physiological, anatomical and root transcriptome analysis were carried out to identify the salt-responsive genes and metabolic pathways associated with salt-tolerant E. arundinaceus genotype IND99-907 and salinity-sensitive sugarcane genotype Co 97010. IND99-907 recorded growth of young leaves, higher proline content, higher relative water content, intact root anatomical structures and lower Na+/K+, Ca2+/K+ and Mg2+/K+ ratio as compared to the sugarcane genotype Co 97010. We have generated four de novo transcriptome assemblies between stressed and control root samples of IND99-907 and Co 97010. A total of 649 and 501 differentially expressed genes (FDR

Roots are the primary conductors of water and nutrients and play a vital role in sustaining growth and yield under stressful environments. The study of plant roots poses methodological difficulties in in situ assessment and sampling, which is especially true for sugarcane (Saccharum spp.). Traditional methods during the 1920s documented the genotypic variation in sugarcane root systems, after which few studies were reported on sugarcane root traits per se until recently. In addition to morphology, rhizosphere characteristics, including allelopathic effects and/or affinity for microbial symbiosis, determine plant establishment and survival. Ultimately, root systems define the above-ground productivity of sugarcane. With the impetus for climate-resilient varieties, it is becoming more relevant to explore and utilize the variability in root system traits of sugarcane. This paper describes multipronged approaches for sugarcane root phenotyping, including field excavation by trench sampling, the use of a root core sampler, raised platforms for root sampling, and raising plants under hydroponic culture, employed by a team of scientists at the Indian Council of Agricultural Research-Sugarcane Breeding Institute (ICAR-SBI). Field excavation by trench sampling is imperative to assess the plant roots in their natural growing environment. The use of raised platforms simulating field conditions and a root core sampler are alternative approaches, with a considerable reduction in time, uniform sample size, and less loss of root material. Hydroponic plant culture allows the study of morphology, anatomical features, and rhizosphere biology, including the exudation of organic compounds and microbial interactions. Data generated from different experiments using diverse sampling methods add to the wealth of information on the root system traits of sugarcane.

In this study, we report the whole genome assembly of Bt 62, a novel isolate harbouring cry8 holotype gene identified by us earlier. Sequencing was carried out using a combination of Illumina NextSeq 500 and Oxford Nanopore sequencing Technologies (ONT). The final assembled genome was 6.13 Mb comprising a circular chromosome and four plasmids. The bioassay studies against Holotrichia serrata (F.) (Coleoptera: Scarabaeidae), a polyphagous pest infesting sugarcane and other crops, indicated significant toxicity to first instar grubs over untreated larvae achieving a highest mean mortality of 91.11% for various doses tested. In vitro proteolytic assay and histopathological studies of the midgut of infected white grubs revealed proteolytic processing of the protoxin and extensive degeneration of larval midgut epithelial cells. The results demonstrate that this novel isolate could be used as a biopesticide or its crystal toxin genes could be expressed in sugarcane and other crops for resistance against H. serrata., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)