Sugarcane Genotypes Research Articles

Identification of Low-Nitrogen-Related miRNAs and Their Target Genes in Sugarcane and the Role of miR156 in Nitrogen Assimilation.

Chemical nitrogen (N) fertilizer is widely used in sugarcane production, especially in China and India. Understanding the molecular mechanisms and mining miRNAs and their target genes associated with nitrogen use efficiency (NUE) in sugarcane can aid in developing the N-efficient varieties, and thus is beneficial to reduce N fertilizer application. In this study, the root miRNA database of N-efficient sugarcane variety ROC22 under low N stress (0.3 mM NH4NO3) for 3 h was constructed, along with their transcriptome-rearranged data. KEGG analysis indicated that those candidate target genes, corresponding to differentially expressed miRNAs, were mainly enriched in N metabolism, amino acid metabolism, carbohydrate metabolism, photosynthesis, and hormone signal transduction pathways. It was found that under low N stress for 0-24 h, there was a negative correlation between miR168 and SPX, along with miR396 and acnA. Furthermore, the expression of miR156 in the roots of ROC22 was significantly up-regulated under low N treatment. Compared with the wild-type, the Arabidopsis plants overexpressing sugarcane miR156 exhibited significantly improved length and surface area of roots, while the expression of one NO3- transporter gene NRT1.1, three N assimilation key genes (NR1, NIR1, and GS), and the activity of two N assimilation key enzymes (NR and GS) were up-regulated under low N treatment. It can be reasonably deduced that sugarcane miR156 can enhance the nitrogen assimilation ability of the overexpressed Arabidopsis plants under low N application, and thus has a potential ability for improving sugarcane NUE. The present study should be helpful for understanding the molecular regulatory network in the N-efficient sugarcane genotype responding to low N stress and could provide the candidate miRNAs with a potential function in improving sugarcane NUE.

Screening of advanced sugarcane genotypes against rust mite

In the screening trial, among the nineteen sugarcane genotypes screened for the reaction to sugarcane rust mite, Abacarus sacchari, only 2 genotypes (009-64 and 0961-07) harboured >1 mites /2 cm2 leaf area while remaining all the genotypes harboured <2 mites/2 cm2 leaf area for the entire crop duration. Morphological characters of genotypes revealed that interveinal distance, leaf area and trichome density were found to influence the A. sacchari negatively. The genotype with high phenol and lower amount of total sugar, reducing sugar, crude protein was found with the lower level of incidence of mites. The study on the role of leaf nutrient on the mite population revealed that genotype with higher potassium content and lower nitrogen levels were found with the minimum incidence of A. sacchari.

Differential Physiological Traits, Ion Homeostasis and Cane Yield of Sub-Tropical Sugarcane Varieties in Response to Long-Term Salinity Stress

Sugarcane grown under a wide range of agro-climatic conditions accounts for ~80% of the sugar production worldwide. Since sugarcane productivity is severely affected by abiotic stresses and hence, an experiment was conducted for two consecutive years during 2020 and 2021 on popular sub-tropical sugarcane varieties. The experiment was laid out in two-factorial RBD consisting of nine sugarcane genotypes (Co 98014, Co 0118, Co 0238, Co 05011, Co 06034, Co 09022, Co 12029, Co 15023 and Co 15027) and salinity treatments (Control, ECiw ~ 4, 8 and 12 dS m−1) in 5 replications. Two budded setts were planted in pots and irrigated with saline water of respective levels till formative phase and observed the build-up in electrical conductivity of soil extract (ECse) from 0.48 (control) to 2.99, 4.81 and 7.08; while further saline irrigation increased the ECse values to 4.48, 6.24 and 9.33 dS m−1 in treatments ECiw ~ 4, 8 and 12 dS m−1, respectively. Increase in soil EC decreased plant survival by 24.1, 47.0 and 79.6% under continued irrigation of ECiw ~ 4, 8, 12 dS m−1 with respect to control. Continued saline irrigation caused significant reduction in growth, which was associated with reduction in relative water content (RWC) and gas exchange traits. RWC decreased by 4.91 to 21.9%, chlorophyll content by 8.46 to 32.75%, photosynthetic rate (Pn) by 16.85 to 91.44%, stomatal conductance by 14.96 to 84.25%, transpiration rate by 14.13% to 89.8% and chlorophyll fluorescence by 5.33 to 42.67% from ECiw ~ 4 to 12 dS m−1, respectively. Significant variations in Na+ and K+ ion content was observed under elevated saline condition in roots, leaves and juice extract of genotypes. Na+/K+ ratio, an important trait for screening salinity tolerance, increased in all genotypes as compared to control, the increase was predominant in susceptible varieties. Single cane weight (SCW) was drastically affected by saline irrigation, with a reduction of 36.4, 68.5 and 83.5% at ECiw ~ 4, 8 and 12 dS m−1, respectively as compared to control, with similar declining trend in juice quality. Based on our results, Co 0238, Co 0118 and Co 98014 were tolerant to salinity stress by maintaining higher Pn, lower leaf Na+/K+ ratio, higher SCW and higher juice sucrose content.

Genetic Diversity Analysis in Tropical Sugarcane Genotypes Using Morphometric Traits

Genetic Diversity Analysis in Tropical Sugarcane Genotypes Using Morphometric Traits

Molecular Characterization of Early Maturing Sugarcane Clones Using Microsatellite Markers

Sugarcane is an important cash crop of the entire world including India. It alone contributes to 75% of the worldwide sugar trade. Molecular markers are powerful tools and provide the basis for the estimation of genetic variability to start reasonable breeding program. Microsatellite markers have unique ability to determine the extent of genetic divergence among sugarcane genotypes. The objective of this study was to evaluate the genetic divergence of 12 early maturing sugarcane clones using 11 SSR markers. A total 55 alleles were found during the amplification of the primers out of which 21 alleles were found unique and 34 alleles were shared. The number of shared alleles per locus ranged from two out of five alleles in the case of primer NKS 1 and nine out of ten alleles in NKS 34. Similarly no. of unique alleles per locus ranged from one out of ten alleles in NKS 34, three out of six alleles in NKS 57. The primer pairs NKS 1 and NKS 8 generated considerably greater percentage of unique alleles. The PIC values revealing allelic diversity and frequency among the genotypes varied from 0.034 in case of NKS 48 to 0.778 in case of NKS 9 with an average of 0.549. Pair-wise combinations of CoSe15451 and CoSe15452 showed the highest similarity with the value of similarity coefficient (0.890). The lowest value of similarity coefficient was found to be 0.490 in the pair CoBln15501 and CoSe01421. The dendogram based on SSR marker analysis grouped the 12 sugarcane clones into four clusters which shows the CoSe15451 and CoSe15452 clones had maximum similarity and CoBln15501 and CoSe15452 clones had maximum diversity between each other.

WGCNA Identifies a Comprehensive and Dynamic Gene Co-Expression Network That Associates with Smut Resistance in Sugarcane.

Sugarcane smut is a major fungal disease caused by Sporisorium scitamineum, which seriously reduces the yield and quality of sugarcane. In this study, 36 transcriptome data were collected from two sugarcane genotypes, YT93-159 (resistant) and ROC22 (susceptible) upon S. scitamineum infection. Data analysis revealed 20,273 (12,659 up-regulated and 7614 down-regulated) and 11,897 (7806 up-regulated and 4091 down-regulated) differentially expressed genes (DEGs) in YT93-159 and ROC22, respectively. A co-expression network was then constructed by weighted gene co-expression network analysis (WGCNA), which identified 5010 DEGs in 15 co-expressed gene modules. Four of the 15 modules, namely, Skyblue, Salmon, Darkorange, and Grey60, were significantly associated with smut resistance. The GO and KEGG enrichment analyses indicated that the DEGs involving in these four modules could be enriched in stress-related metabolic pathways, such as MAPK and hormone signal transduction, plant-pathogen interaction, amino acid metabolism, glutathione metabolism, and flavonoid, and phenylpropanoid biosynthesis. In total, 38 hub genes, including six from the Skyblue module, four from the Salmon module, 12 from the Darkorange module, and 16 from the Grey60 module, were screened as candidate hub genes by calculating gene connectivity in the corresponding network. Only 30 hub genes were amplifiable with RT-qPCR, of which 27 were up-regulated upon S. scitamineum infection. The results were consistent with the trend of gene expression in RNA-Seq, suggesting their positive roles in smut resistance. Interestingly, the expression levels of AOX, Cyb5, and LAC were higher in ROC22 than in YT93-159, indicating these three genes may act as negative regulators in response to S. scitamineum infection. This study revealed the transcriptome dynamics in sugarcane challenged by S. scitamineum infection and provided gene targets for smut resistance breeding in sugarcane.

A high-throughput lipidomics and transcriptomic approach reveals novel compounds from sugarcane linked with promising therapeutic potential against COVID-19.

Sugarcane (Saccharum ssp., Poaceae) provides enormous metabolites such as sugars, lipid, and other dietary metabolites to humans. Among them, lipids are important metabolites that perform various functions and have promising pharmacological value. However, in sugarcane, few studies are focusing on lipidomics and few lipid compounds were reported, and their pharmacological values are not explored yet. The transcriptomic and widely targeted lipidomics approach quantified 134 lipid compounds from the rind of six sugarcane genotypes. These lipid compounds include 57 fatty acids, 30 lysophosphatidylcholines, 23 glycerol esters, 21 lysophosphatidylethanolamines, 2 phosphatidylcholines, and 1 sphingolipid. Among them, 119 compounds were first time reported in sugarcane rind. Seventeen lipids compounds including 12 fatty acids, 2 glycerol lipids, LysoPC 16:0, LysoPE 16:0, and choline alfoscerate were abundantly found in the rind of sugarcane genotypes. From metabolic and transcriptomic results, we have developed a comprehensive lipid metabolic pathway and highlighted key genes that are differentially expressed in sugarcane. Several genes associated with α-linolenic acid and linoleic acid biosynthesis pathways were highly expressed in the rind of the ROC22 genotype. ROC22 has a high level of α-linolenic acid (an essential fatty acid) followed by ROC16. Moreover, we have explored pharmacological values of lipid compounds and found that the 2-linoleoylglycerol and gingerglycolipid C have strong binding interactions with 3CLpro of SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) and these compounds can be utilized against SARS-CoV-2 as therapeutic agents. The transcriptome, metabolome, and bioinformatics analysis suggests that the sugarcane cultivars have a diversity of lipid compounds having promising therapeutic potential, and exploring the lipid metabolism will help to know more compounds that have promising cosmetic and pharmacological value.

Effect of thermotherapy, Leifsonia xyli subsp. xyli titres, sugarcane genotype and diagnostic techniques on ratoon stunt control in Brazil.

AimsTo examine the interaction of diagnostic techniques, initial titres of Leifsonia xyli subsp. xyli (Lxx), sugarcane genotype and thermotherapy on ratoon stunt (RSD) control.Methods and ResultsSingle buds of RB867515, RB92579 and RB966928 were submitted to 50°C/2 h or 52°C/30 min under factorial block design and five replications; results were checked 9 months later by serological (DBI) and molecular (PCR) techniques. A 10,000 bootstrapping simulations were performed to infer the best plot size based on the experimental coefficient of variation. Analysis of variance showed significance only on initial Lxx titres and RSD control. Despite the absence of significance in the overall analysis, minor differences in control success with different methods and cultivars are predicted to have a major epidemiological impact on RSD, considering successive harvests and vegetative increase. According to an epidemiological interpretation, the 50°C/2 h treatment was more effective, cultivar RB966928 was the most susceptible and the PCR‐based method was the most sensitive for pathogen detection. The minimum required plants per plot was 15, indicating high precision of our experimentConclusionsData interpretation considered both the statistical analysis and the epidemiology aspect of RSD in order to improve RSD management. The Brazilian sugarcane industry will benefit from this approach since it is not using it.Significance and Impact of the StudyThis is the first study that examined multiple factors that affect RSD control. Our work pinpointed the importance of the thermotherapy, its best combination as well as the diagnostic test. Also, the effect of the cultivar to respond to management strategies. Because the epidemiological aspect of RSD was taken into consideration, results of our work can have an impact on RSD control in the field.

Effect of Waterlogging on the Morphological Characters of Mutant Sugarcane (Saccharum officinarum L.) in the Early Stage

Waterlogging stress is a limiting factor in sugarcane growth due to global climate change. In Indonesia,Waterlogging stress in sugarcane areas is caused by high rainfall and the increasing number of sugarcaneplants cultivated on land with less than optimal drainage systems. In this study, four sugarcane genotypes,1 Bululawang commercial genotype (M1), and three mutation breeding genotypes using EMS mutagens(M2, M3 & M4) were subjected to waterlogging stress for 90 days. They observed data at 30 DAT, 60 DAT,and 90 DAT. The study results showed that waterlogging stress had an impact on decreasing leaf area, leafrelative water content, chlorophyll content, photosynthetic efficiency, and inhibition of plant height growth.Sugarcane will respond to waterlogging stress conditions; a series of response forms given by plants includeanatomical, morphological, physiological, and biochemical responses as a form of resistance in dealingwith waterlogging stress. The sugarcane M4 genotype gave the best growth response under waterloggingstress through indicators of leaf area, RWC, chlorophyll content, photochemical efficiency, and plant heightcompared to other genotypes. All sugarcane genotypes showed changes in root morphology throughadventitious root formation in response to waterlogging conditions.

Sugarcane Genotypes with Contrasting Biological Nitrogen Fixation Efficiencies Differentially Modulate Nitrogen Metabolism, Auxin Signaling, and Microorganism Perception Pathways.

Sugarcane is an economically important crop that is used for the production of fuel ethanol. Diazotrophic bacteria have been isolated from sugarcane tissues, without causing visible plant anatomical changes or disease symptoms. These bacteria can be beneficial to the plant by promoting root growth and an increase in plant yield. Different rates of Biological Nitrogen Fixation (BNF) were observed in different genotypes. The aim of this work was to conduct a comprehensive molecular and physiological analysis of two model genotypes for contrasting BNF efficiency in order to unravel plant genes that are differentially regulated during a natural association with diazotrophic bacteria. A next-generation sequencing of RNA samples from the genotypes SP70-1143 (high-BNF) and Chunee (low-BNF) was performed. A differential transcriptome analysis showed that several pathways were differentially regulated among the two BNF-contrasting genotypes, including nitrogen metabolism, hormone regulation and bacteria recognition. Physiological analyses, such as nitrogenase and GS activity quantification, bacterial colonization, auxin response and root architecture evaluation, supported the transcriptome expression analyses. The differences observed between the genotypes may explain, at least in part, the differences in BNF contributions. Some of the identified genes might be involved in key regulatory processes for a beneficial association and could be further used as tools for obtaining more efficient BNF genotypes.

Row Spacing, Levels of Fertilizers and Genotypes Influencing Growth, Nutrient Uptake and Yield of Sugarcane (Saccharum spp.) Grown under Calcareous Soil

A field experiment was conducted at the crop research center of Dr. Rajendra Prasad Central Agricultural University, Pusa (Bihar) during 2020-21 to access the effect of row spacing, levels of fertilizers and genotypes on growth, nutrient uptake and yield parameters of sugarcane (Saccharum spp.) grown under calcareous soil. The experiment was laid out in factorial randomized block design with three replications. Data analysis revealed that significantly higher germination, plant population, number of millable canes, nutrient uptake and cane yield were recorded with planting at row spacing of 90 cm. Irrespective of row spacing and genotypes, application of 150% NPK of RDF exhibited higher plant population (155.2 x 103 /ha at 120 DAP and 159.0 x 103 /ha at 150 DAP), plant height (205.9 cm, 258.0 cm and 325.9 cm at 150 DAP, 180 DAP and 210 DAP, respectively), number of millable canes (123.5 x 103 /ha), length of millable canes (271.5 cm), cane diameter (2.63 cm), nutrient uptake (287.3 Kg ha-1, 28.8 Kg ha-1, 302.6 Kg ha-1 and 28.1 Kg ha-1 for N, P, K and S, respectively) and cane yield (87.4 t ha-1). Most of the growth and yield attributing characters like germination, plant population, plant height, number of millable canes, length of millable canes, cane diameter, nutrient uptake and cane yield were observed significantly higher in genotype CoP 15436. The results demonstrate that sugarcane growers may increase growth, nutrient uptake and cane yield per unit area by planting sugarcane at 90 cm spacing, applying 150% NPK of RDF (225 Kg N ha-1 : 127.5 Kg P2O5 ha-1 : 90 Kg K2O ha-1) as fertilizer input and adopting genotype CoP 15436 in cultivation practice which proved itself as an elite sugarcane genotype.

Correlation and Path Analysis in Early Maturing Sugarcane: Climate Change and Environmental Impact

An investigation was undertaken to identify early maturing sugarcane genotypes for higher sugar yield at the Research Farm of DRPCAU, Pusa, Samastipur, Bihar during the spring season of 2018, the experiment was carried out in Randomized Block Climate change is expected to have important consequences for sugarcane production in the world, especially in the developing countries because of relatively low adaptive capacity, high vulnerability to natural hazards, and poor forecasting systems and mitigating strategies. Sugarcane production may have been negatively affected and will continue to be considerably affected by increases in the frequency and intensity of extreme environmental conditions due to climate change. Design with three replications. Correlation and path analysis in twelve genotypes of sugarcane for twenty one different morphological and juice quality characters were studied in relation to the checks viz. CoLk94184 and CoSe95422. Analysis of correlation revealed that the character sugar yield had highly positive genotypic correlation with traits number of millable canes at harvest (0.977), followed by cane yield at harvest (0.963). However, it was negatively correlated with purity percentage at the 8th month stage (-0.491), cane diameter at harvest (-0.363), number of internodes at harvest (-0.263), length of internodes at harvest (-0.081) and fibre percentage at harvest (-0.039). The trait cane yield at harvest (0.955**) was found to have a highly significant and positive phenotypic association, followed by single cane weight at harvest (0.820**) and germination percentage at 45 DAP (0.510**).On the other hand, it was found that the traits cane diameter at harvest (-0.236), number of internodes at harvest (-0.151) and length of internodes at harvest (-0.099) had non-significant negative phenotypic associations with sugar yield. Positive direct effect on sugar yield at phenotypic level was exerted maximally by cane yield at harvest (t/ha) (1.51) followed by CCS percentage at 10th month stage (0.29) and pol in juice at 10th month stage (0.21), germination Percentage at 45 DAP (%), cane diameter (cm) and length of internode (cm), whereas at genotypic level maximum positive direct effect was observed in the case of pol percentage in cane at harvest followed by single cane weight (kg) and brix percentage at 10th month.

Amelioration of lead toxicity by ascorbic acid in sugarcane (Saccharum officinarum L.) under in vitro condition.

Agricultural sites are polluted with various metal ions worldwide. Ascorbic acid (AA) plays diverse roles in plant growth, development, and the regulation of cellular mechanisms against environmental stress. This study provides the relationship between morphological and biochemical parameters involved in the amelioration of Pb toxicity in three sugarcane (Saccharum officinarum L.) genotypes (YT-53, CP-77-400, NSG-59) by using six concentrations of Pb(NO3)2 under in vitro conditions. Morphological and biochemical parameters of ascorbic acid pretreated and non-pretreated calli were compared at each Pb(NO3)2 concentration. Ascorbic acid-pretreated calli have better callus growth and regeneration potential than non-treated calli under increased Pb concentration. Biochemical parameters such as antioxidant enzyme activity (peroxidase (POD), superoxide dismutase (SOD), catalase (CAT)) increased under increased Pb concentration. Ascorbic acid pretreatment further enhanced the POD and SOD activity, while CAT activity and total soluble protein contents of pretreated calli did not change significantly. Ascorbic acid ameliorated the Pb toxicity morphologically but showed uneven behavior towards biochemical parameters. Different genotypic behaviors versus different treatments were also observed. In the future, information from this study can be used to develop the metal-resistant sugarcane genotype against metal stress under in vitro conditions.

Evaluation of sugarcane genotypes against yellow leaf disorder under field conditions in subtropical India

Sugarcane yellow leaf (YL) caused by Sugarcane yellow leaf virus (ScYLV) and leaf yellows (LY) caused by Sugarcane leaf yellows phytoplasma (SCYP) is major constraint in sugarcane cultivation. In the present study, identification of resistance sources against YL or LY under field conditions were carried out on 142 sugarcane genotypes evaluated during 2016–2017 and 2017–2018 crop seasons. Field evaluation was carried out using 0–5 rating scale. Among the 142 sugarcane genotypes, 102 genotypes during 2016–2017 and 86 genotypes during 2017–2018 season showed resistant reaction against yellowing. While 22 and 13 genotypes during 2016–2017 and 2017–2018 crop seasons, respectively, showed moderately resistant reaction. Similarly, 13 genotypes showed moderately susceptible reaction against leaf yellowing during both the crop seasons. The presence of phytoplasma in 55 symptomatic sugarcane genotypes was detected by nested PCR assay. The 86 asymptomatic sugarcane genotypes were found as a source of resistance against LY from the present investigation.

Sugarcane yield prediction and genotype selection using unmanned aerial vehicle‐based hyperspectral imaging and machine learning

AbstractSugarcane (Saccharum spp. interspecific hybrids), a high biomass perennial crop, in which manual data collection for early yield prediction, through its growth cycle (∼12 mo long), is labor intensive and time consuming. Alternately, aerial imagery can be explored to predict yield‐related components and high‐throughput phenotyping for genetic selection. In this study, aerial imagery and ground data were collected in Stage IV (final stage of genotype selection) of the Florida sugarcane cultivar development program to evaluate the use of unmanned aerial vehicles in yield prediction (tons of cane per hectare [TCH], sucrose concentration, and tons of sugar per hectare [TSH]) in multiple new genotypes (13 in plant cane crop, nine in first ratoon crop). Aerial imagery data were collected using hyperspectral sensor, and yield data were collected through manual sampling of sugarcane stalks at harvest. The gradient‐boosting regression tree model was selected based on low mean absolute percentage error on multiple dates (April, July, and September) to determine the best timing of yield predictions. Results showed that yield was predicted with greater accuracy in July in plant crop and April in the first ratoon crop. Also, sucrose percentage was predicted with greater accuracy (94% in plant crop and 93% in first ratoon crop) than TCH and TSH. Although only two out of the top five genotypes were common in both selection methods (measured vs. predicted yields) in Stage IV, high accuracy in TCH and sucrose percentage shows that aerial imagery may be useful in making genotype selection in early stages when actual yield estimation is not feasible.

Taxonomically Restricted Genes Are Associated With Responses to Biotic and Abiotic Stresses in Sugarcane (Saccharum spp.).

Orphan genes (OGs) are protein-coding genes that are restricted to particular clades or species and lack homology with genes from other organisms, making their biological functions difficult to predict. OGs can rapidly originate and become functional; consequently, they may support rapid adaptation to environmental changes. Extensive spread of mobile elements and whole-genome duplication occurred in the Saccharum group, which may have contributed to the origin and diversification of OGs in the sugarcane genome. Here, we identified and characterized OGs in sugarcane, examined their expression profiles across tissues and genotypes, and investigated their regulation under varying conditions. We identified 319 OGs in the Saccharum spontaneum genome without detected homology to protein-coding genes in green plants, except those belonging to Saccharinae. Transcriptomic analysis revealed 288 sugarcane OGs with detectable expression levels in at least one tissue or genotype. We observed similar expression patterns of OGs in sugarcane genotypes originating from the closest geographical locations. We also observed tissue-specific expression of some OGs, possibly indicating a complex regulatory process for maintaining diverse functional activity of these genes across sugarcane tissues and genotypes. Sixty-six OGs were differentially expressed under stress conditions, especially cold and osmotic stresses. Gene co-expression network and functional enrichment analyses suggested that sugarcane OGs are involved in several biological mechanisms, including stimulus response and defence mechanisms. These findings provide a valuable genomic resource for sugarcane researchers, especially those interested in selecting stress-responsive genes.

Leaf transcriptome profiling of contrasting sugarcane genotypes for drought tolerance under field conditions

Drought is the most detrimental abiotic stress to sugarcane production. Nevertheless, transcriptomic analyses remain scarce for field-grown plants. Here we performed comparative transcriptional profiling of two contrasting sugarcane genotypes, ‘IACSP97-7065’ (drought-sensitive) and ‘IACSP94-2094’ (drought-tolerant) grown in a drought-prone environment. Physiological parameters and expression profiles were analyzed at 42 (May) and 117 (August) days after the last rainfall. The first sampling was done under mild drought (soil water potential of −60 kPa), while the second one was under severe drought (soil water potential of −75 kPa). Microarray analysis revealed a total of 622 differentially expressed genes in both sugarcane genotypes under mild and severe drought stress, uncovering about 250 exclusive transcripts to ‘IACSP94-2094’ involved in oxidoreductase activity, transcriptional regulation, metabolism of amino acids, and translation. Interestingly, the enhanced antioxidant system of ‘IACSP94-2094’ may protect photosystem II from oxidative damage, which partially ensures stable photochemical activity even after 117 days of water shortage. Moreover, the tolerant genotype shows a more extensive set of responsive transcription factors, promoting the fine-tuning of drought-related molecular pathways. These results help elucidate the intrinsic molecular mechanisms of a drought-tolerant sugarcane genotype to cope with ever-changing environments, including prolonged water deficit, and may be useful for plant breeding programs.

Response of sugarcane genotypes to varying planting environments under two distinct agro-climatic zones of Punjab, India

Response of sugarcane genotypes to varying planting environments under two distinct agro-climatic zones of Punjab, India

English

An efficient callus-mediated regeneration system was developed for high-frequency production of planting material of sugarcane genotypes LSC and B36464. Spindle leaf segments cultured on MS basal medium supplemented with 2,4-D or picloram at 1, 2, 3 or 4 mg/L resulted in callus induction. Callus induction was higher on 2,4-D amended medium compared to picloram. Nevertheless, for both auxins, callus induction improved significantly (p ≤ 0.05) with increasing concentration; the highest (82 and 82.5% for B36464 and LSC respectively) was achieved at 4 mg/L. For shoot induction, calli were transferred to MS medium supplemented with BAP (0.1, 0.5, 1.0 or 1.5 mg/L). The highest number of shoots (18.13 and 16.75 for B36464 and LSC respectively) was achieved at 1.5 mg/L. Serial subculture at four-week intervals on a higher concentration of BAP (2.5 mg/L), in combination with NAA (0.5 mg/L) and GA3 (0.5 mg/L), resulted in a four-fold increase in shoot number within 16 weeks. On this medium, 40% of shoot clusters of B36464 formed well-defined shoots. On MS medium containing solely NAA (3 mg/L), 88 and 72% (B36464 and LSC respectively) formed roots. Post-flask acclimatisation of the plantlets led to 85 and 91% survival rates in LSC and B36464 respectively after which plantlets were successfully transferred to field conditions. The callus-mediated regeneration system reported in this study has the potential to sustainably provide sugarcane planting material for the emerging sugar industry in Ghana.   Key words: Sugarcane, spindle leaf explants, callus-mediated organogenesis, plantlet regeneration, 2,4-D, Picloram.

Classification of sugarcane genotypes susceptible and resistant to the initial attack of sugarcane borer Diatraea saccharalis using epicuticular wax composition

Identifying compounds present in the sugarcane epicuticular wax and using these compounds to classify the genotypes susceptible and resistant to the initial attack of sugarcane borer (Diatraea saccharalis) was the aim of this study. A greenhouse experiment was performed in a factorial scheme with and without borer infestation using genotypes previously characterized as resistant or susceptible in field-based experiments. Sugarcane whorls of six-month-old plants were collected before (BI) and after (AI) 72 h of sugarcane borer infestation. The sugarcane epicuticular wax was extracted in both times, i.e., BI and AI and its chemical composition was assessed by gas chromatography coupled to mass spectrometry (GC-MS). Twenty-five compounds were identified for both BI and AI. Classification models were built using partial least squares for discriminant analysis (PLS-DA) and linear discriminant analysis (LDA). Variable selection methods were used to improve the classification models. Ordered predictors selection for discriminant analysis (OPSDA) selected compounds that correctly classified all the test samples before borer infestation (Error = 0.000), and exhibited the most suitable classification parameters for the test set after borer infestation (Error = 0.111). The C30 pentacyclic triterpene friedelin and a high alcohol/aldehyde ratio were associated with the classification of resistant genotypes. Our findings have applicability in developing a screening methodology for breeding programs interested in identifying genotypes resistant to the initial feeding of sugarcane borer.