Kandelia candel Thioredoxin f Confers Osmotic Stress Tolerance in Transgenic Tobacco

Water deficit caused by osmotic stress and drought limits crop yield and tree growth worldwide. Screening and identifying candidate genes from stress-resistant species are a genetic engineering strategy to increase drought resistance. In this study, an increased concentration of mannitol resulted in elevated expression of thioredoxin f (KcTrxf) in the nonsecretor mangrove species Kandelia candel. By means of amino acid sequence and phylogenetic analysis, the mangrove Trx was classified as an f-type thioredoxin. Subcellular localization showed that KcTrxf localizes to chloroplasts. Enzymatic activity characterization revealed that KcTrxf recombinant protein possesses the disulfide reductase function. KcTrxf overexpression contributes to osmotic and drought tolerance in tobacco in terms of fresh weight, root length, malondialdehyde (MDA) content, and hydrogen peroxide (H2O2) production. KcTrxf was shown to reduce the stomatal aperture by enhancing K+ efflux in guard cells, which increased the water-retaining capacity in leaves under drought conditions. Notably, the abscisic acid (ABA) sensitivity was increased in KcTrxf-transgenic tobacco, which benefits plants exposed to drought by reducing water loss by promoting stomatal closure. KcTrxf-transgenic plants limited drought-induced H2O2 in leaves, which could reduce lipid peroxidation and retain the membrane integrity. Additionally, glutathione (GSH) contributing to reactive oxygen species (ROS) scavenging and transgenic plants are more efficient at regenerating GSH from oxidized glutathione (GSSG) under conditions of drought stress. Notably, KcTrxf-transgenic plants had increased glucose and fructose contents under drought stress conditions, presumably resulting from KcTrxf-promoted starch degradation under water stress. We conclude that KcTrxf contributes to drought tolerance by increasing the water status, by enhancing osmotic adjustment, and by maintaining ROS homeostasis in transgene plants.

Download Full-text

Overexpression of the pitaya phosphoethanolamine N-methyltransferase gene (HpPEAMT) enhanced simulated drought stress in tobacco

Plant Cell Tissue and Organ Culture (PCTOC) ◽

10.1007/s11240-021-02040-3 ◽

2021 ◽

Author(s):

Ai-Hua Wang ◽

Lan Yang ◽

Xin-Zhuan Yao ◽

Xiao-Peng Wen

Keyword(s):

Drought Stress ◽

Stress Response ◽

Transgenic Plants ◽

Drought Tolerance ◽

Transgenic Tobacco ◽

Sequence Similarity ◽

Amino Acid Sequence Similarity ◽

Transgenic Tobacco Plants ◽

Wild Type ◽

Tobacco Plants

AbstractPhosphoethanolamine N-methyltransferase (PEAMTase) catalyzes the methylation of phosphoethanolamine to produce phosphocholine and plays an important role in the abiotic stress response. Although the PEAMT genes has been isolated from many species other than pitaya, its role in the drought stress response has not yet been fully elucidated. In the present study, we isolated a 1485 bp cDNA fragment of HpPEAMT from pitaya (Hylocereus polyrhizus). Phylogenetic analysis showed that, during its evolution, HpPEAMT has shown a high degree of amino acid sequence similarity with the orthologous genes in Chenopodiaceae species. To further investigate the function of HpPEAMT, we generated transgenic tobacco plants overexpressing HpPEAMT, and the transgenic plants accumulated significantly more glycine betaine (GB) than did the wild type (WT). Drought tolerance trials indicated that, compared with those of the wild-type (WT) plants, the roots of the transgenic plants showed higher drought tolerance ability and exhibited improved drought tolerance. Further analysis revealed that overexpression of HpPEAM in Nicotiana tabacum resulted in upregulation of transcript levels of GB biosynthesis-related genes (NiBADH, NiCMO and NiSDC) in the leaves. Furthermore, compared with the wild-type plants, the transgenic tobacco plants displayed a significantly lower malondialdehyde (MDA) accumulation and higher activities of the superoxide dismutase (SOD) and peroxidase (POD) antioxidant enzymes under drought stress. Taken together, our results suggested that HpPEAMT enhanced the drought tolerance of transgenic tobacco.

Download Full-text

A Novel WRKY Transcription Factor from Ipomoea trifida, ItfWRKY70, Confers Drought Tolerance in Sweet Potato

International Journal of Molecular Sciences ◽

10.3390/ijms23020686 ◽

2022 ◽

Vol 23 (2) ◽

pp. 686

Author(s):

Sifan Sun ◽

Xu Li ◽

Shaopei Gao ◽

Nan Nie ◽

Huan Zhang ◽

...

Keyword(s):

Drought Stress ◽

Transgenic Plants ◽

Drought Tolerance ◽

Sweet Potato ◽

Stress Responses ◽

Leaf Tissue ◽

Stomatal Aperture ◽

Ros Scavenging ◽

Ipomoea Trifida ◽

Positive Role

WRKY transcription factors are one of the important families in plants, and have important roles in plant growth, abiotic stress responses, and defense regulation. In this study, we isolated a WRKY gene, ItfWRKY70, from the wild relative of sweet potato Ipomoea trifida (H.B.K.) G. Don. This gene was highly expressed in leaf tissue and strongly induced by 20% PEG6000 and 100 μM abscisic acid (ABA). Subcellar localization analyses indicated that ItfWRKY70 was localized in the nucleus. Overexpression of ItfWRKY70 significantly increased drought tolerance in transgenic sweet potato plants. The content of ABA and proline, and the activity of SOD and POD were significantly increased, whereas the content of malondialdehyde (MDA) and H2O2 were decreased in transgenic plants under drought stress. Overexpression of ItfWRKY70 up-regulated the genes involved in ABA biosynthesis, stress-response, ROS-scavenging system, and stomatal aperture in transgenic plants under drought stress. Taken together, these results demonstrated that ItfWRKY70 plays a positive role in drought tolerance by accumulating the content of ABA, regulating stomatal aperture and activating the ROS scavenging system in sweet potato.

Download Full-text

Overexpression of a Voltage-Dependent Anion-Selective Channel (VDAC) Protein-Encoding Gene, MsVDAC, from Medicago sativa Confers Cold and Drought Tolerance to Transgenic Tobacco

Genes ◽

10.3390/genes12111706 ◽

2021 ◽

Vol 12 (11) ◽

pp. 1706

Author(s):

Mei Yang ◽

Xinhang Duan ◽

Zhaoyu Wang ◽

Hang Yin ◽

Junrui Zang ◽

...

Keyword(s):

Drought Stress ◽

Drought Tolerance ◽

Cold Stress ◽

Medicago Sativa ◽

Transgenic Tobacco ◽

Soluble Sugars ◽

Ros Scavenging ◽

Osmotic Homeostasis ◽

Voltage Dependent ◽

Stress Responsive Genes

Voltage-dependent anion channels (VDACs) are highly conserved proteins that are involved in the translocation of tRNA and play a key role in modulating plant senescence and multiple pathways. However, the functions of VDACs in plants are still poorly understood. Here, a novel VDAC gene was isolated and identified from alfalfa (Medicago sativa L.). MsVDAC localized to the mitochondria, and its expression was highest in alfalfa roots and was induced in response to cold, drought and salt treatment. Overexpression of MsVDAC in tobacco significantly increased MDA, GSH, soluble sugars, soluble protein and proline contents under cold and drought stress. However, the activities of SOD and POD decreased in transgenic tobacco under cold stress, while the O2− content increased. Stress-responsive genes including LTP1, ERD10B and Hxk3 were upregulated in the transgenic plants under cold and drought stress. However, GAPC, CBL1, BI-1, Cu/ZnSOD and MnSOD were upregulated only in the transgenic tobacco plants under cold stress, and GAPC, CBL1, and BI-1 were downregulated under drought stress. These results suggest that MsVDAC provides cold tolerance by regulating ROS scavenging, osmotic homeostasis and stress-responsive gene expression in plants, but the improved drought tolerance via MsVDAC may be mainly due to osmotic homeostasis and stress-responsive genes.

Download Full-text

Overexpression of DBF-Interactor Protein 6 Containing an R3H Domain Enhances Drought Tolerance in Populus L. (Populus tomentosa)

Frontiers in Plant Science ◽

10.3389/fpls.2021.601585 ◽

2021 ◽

Vol 12 ◽

Author(s):

Yang Liu ◽

Xinzhuan Yao ◽

Lu Zhang ◽

Litang Lu ◽

Renxiang Liu

Keyword(s):

Drought Stress ◽

Transgenic Plants ◽

Drought Tolerance ◽

Transgenic Tobacco ◽

Antioxidant Defense ◽

Growth Yield ◽

Animal Husbandry ◽

Defense Enzymes ◽

Wild Type ◽

Antioxidant Defense Enzymes

Drought is the primary disaster that endangers agricultural production, including animal husbandry, and affects the distribution, growth, yield, and quality of crops. Previous study had revealed that DIP, as a potential regulator of DBF activity, played an important role in response to drought stress in maize. In this study, a total of 67 DIPs were identified from seventeen land plants, including six tobacco DIPs (NtDIPs). NtDIP6 gene was further selected as a candidate gene for subsequent experiments based on the phylogenetic analysis and structural analysis. The transgenic tobacco and poplar plants over-expressing NtDIP6 gene were generated using the Agrobacterium- mediated method. Although there was not phenotypic difference between transgenic plants and wild-type plants under normal conditions, overexpression of the NtDIP6 gene in transgenic tobacco and poplar plants enhanced the drought tolerance under drought treatments in comparison with the wild type. The content of antioxidant defense enzymes peroxidase (POD), catalase (CAT), and the photosynthetic rate increased in NtDIP6-Ox transgenic tobacco and poplar plants, while the content of malondialdehyde decreased, suggesting that the overexpression of NtDIP6 enhances the antioxidant capacity of transgenic poplar. Furthermore, the results of qRT-PCR showed that the level of expression of drought-related response genes significantly increased in the NtDIP6-Ox transgenic plants. These results indicated that NtDIP6, as a positive response regulator, improves drought stress tolerance by scavenging superoxide via the accumulation of antioxidant defense enzymes.

Download Full-text

Insights into Drought Stress Signaling in Plants and the Molecular Genetic Basis of Cotton Drought Tolerance

Cells ◽

10.3390/cells9010105 ◽

2019 ◽

Vol 9 (1) ◽

pp. 105 ◽

Cited By ~ 14

Author(s):

Tahir Mahmood ◽

Shiguftah Khalid ◽

Muhammad Abdullah ◽

Zubair Ahmed ◽

Muhammad Kausar Nawaz Shah ◽

...

Keyword(s):

Drought Stress ◽

Quantitative Trait Loci ◽

Drought Tolerance ◽

Quantitative Trait ◽

Genetic Basis ◽

Stomatal Closure ◽

Stress Signaling ◽

Functional Genomic ◽

Ros Scavenging ◽

Trait Loci

Drought stress restricts plant growth and development by altering metabolic activity and biological functions. However, plants have evolved several cellular and molecular mechanisms to overcome drought stress. Drought tolerance is a multiplex trait involving the activation of signaling mechanisms and differentially expressed molecular responses. Broadly, drought tolerance comprises two steps: stress sensing/signaling and activation of various parallel stress responses (including physiological, molecular, and biochemical mechanisms) in plants. At the cellular level, drought induces oxidative stress by overproduction of reactive oxygen species (ROS), ultimately causing the cell membrane to rupture and stimulating various stress signaling pathways (ROS, mitogen-activated-protein-kinase, Ca2+, and hormone-mediated signaling). Drought-induced transcription factors activation and abscisic acid concentration co-ordinate the stress signaling and responses in cotton. The key responses against drought stress, are root development, stomatal closure, photosynthesis, hormone production, and ROS scavenging. The genetic basis, quantitative trait loci and genes of cotton drought tolerance are presented as examples of genetic resources in plants. Sustainable genetic improvements could be achieved through functional genomic approaches and genome modification techniques such as the CRISPR/Cas9 system aid the characterization of genes, sorted out from stress-related candidate single nucleotide polymorphisms, quantitative trait loci, and genes. Exploration of the genetic basis for superior candidate genes linked to stress physiology can be facilitated by integrated functional genomic approaches. We propose a third-generation sequencing approach coupled with genome-wide studies and functional genomic tools, including a comparative sequenced data (transcriptomics, proteomics, and epigenomic) analysis, which offer a platform to identify and characterize novel genes. This will provide information for better understanding the complex stress cellular biology of plants.

Download Full-text

The bHLH transcription factor AhbHLH112 improves the drought tolerance of peanut

BMC Plant Biology ◽

10.1186/s12870-021-03318-6 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Chunjuan Li ◽

Caixia Yan ◽

Quanxi Sun ◽

Juan Wang ◽

Cuiling Yuan ◽

...

Keyword(s):

Drought Stress ◽

Transgenic Plants ◽

Drought Tolerance ◽

Target Genes ◽

Gene Families ◽

Bhlh Transcription Factor ◽

Plant Responses ◽

Ros Scavenging ◽

Drought Treatment ◽

Stress Responding

Abstract Background Basic helix-loop-helix (bHLH) transcription factors (TFs) are one of the largest gene families in plants. They regulate gene expression through interactions with specific motifs in target genes. bHLH TFs are not only universally involved in plant growth but also play an important role in plant responses to abiotic stress. However, most members of this family have not been functionally characterized. Results Here, we characterized the function of a bHLH TF in the peanut, AhHLH112, in response to drought stress. AhHLH112 is localized in the nucleus and it was induced by drought stress. The overexpression of this gene improves the drought tolerance of transgenic plants both in seedling and adult stages. Compared to wild-type plants, the transgenic plants accumulated less reactive oxygen species (ROS), accompanied by increased activity and transcript levels of antioxidant enzymes (superoxide dismutase, peroxidase and catalase). In addition, the WT plants demonstrated higher MDA concentration levels and higher water loss rate than the transgenic plants under drought treatment. The Yeast one-hybrid result also demonstrates that AhbHLH112 directly and specifically binds to and activates the promoter of the peroxidase (POD) gene. Besides, overexpression of AhHLH112 improved ABA level under drought condition, and elevated the expression of genes associated with ABA biosynthesis and ABA responding, including AtNCED3 and AtRD29A. Conclusions Drawing on the results of our experiments, we propose that, by improving ROS-scavenging ability, at least in part through the regulation of POD -mediated H2O2 homeostasis, and possibly participates in ABA-dependent stress-responding pathway, AhbHLH112 acts as a positive factor in drought stress tolerance.

Download Full-text

The Rice GLYCINE-RICH PROTEIN 3 Confers Drought Tolerance by Regulating mRNA Stability of ROS Scavenging-Related Genes

Rice ◽

10.1186/s12284-021-00473-0 ◽

2021 ◽

Vol 14 (1) ◽

Author(s):

Jae Sung Shim ◽

Su-Hyun Park ◽

Dong-Keun Lee ◽

Youn Shic Kim ◽

Soo-Chul Park ◽

...

Keyword(s):

Drought Stress ◽

Transgenic Plants ◽

Drought Tolerance ◽

Mrna Stability ◽

Molecular Mechanisms ◽

Rna Binding ◽

Protein Structures ◽

Ros Scavenging ◽

Ros Accumulation ◽

Glycine Rich Protein

Abstract Background Plant glycine-rich proteins are categorized into several classes based on their protein structures. The glycine-rich RNA binding proteins (GRPs) are members of class IV subfamily possessing N-terminus RNA-recognition motifs (RRMs) and proposed to be involved in post-transcriptional regulation of its target transcripts. GRPs are involved in developmental process and cellular stress responses, but the molecular mechanisms underlying these regulations are still elusive. Results Here, we report the functional characterization of rice GLYCINE-RICH PROTEIN 3 (OsGRP3) and its physiological roles in drought stress response. Both drought stress and ABA induce the expression of OsGRP3. Transgenic plants overexpressing OsGRP3 (OsGRP3OE) exhibited tolerance while knock-down plants (OsGRP3KD) were susceptible to drought compared to the non-transgenic control. In vivo, subcellular localization analysis revealed that OsGRP3-GFP was transported from cytoplasm/nucleus into cytoplasmic foci following exposure to ABA and mannitol treatments. Comparative transcriptomic analysis between OsGRP3OE and OsGRP3KD plants suggests that OsGRP3 is involved in the regulation of the ROS related genes. RNA-immunoprecipitation analysis revealed the associations of OsGRP3 with PATHOGENESIS RELATED GENE 5 (PR5), METALLOTHIONEIN 1d (MT1d), 4,5-DOPA-DIOXYGENASE (DOPA), and LIPOXYGENASE (LOX) transcripts. The half-life analysis showed that PR5 transcripts decayed slower in OsGRP3OE but faster in OsGRP3KD, while MT1d and LOX transcripts decayed faster in OsGRP3OE but slower in OsGRP3KD plants. H2O2 accumulation was reduced in OsGRP3OE and increased in OsGRP3KD plants compared to non-transgenic plants (NT) under drought stress. Conclusion OsGRP3 plays a positive regulator in rice drought tolerance and modulates the transcript level and mRNA stability of stress-responsive genes, including ROS-related genes. Moreover, OsGRP3 contributes to the reduction of ROS accumulation during drought stress. Our results suggested that OsGRP3 alleviates ROS accumulation by regulating ROS-related genes’ mRNA stability under drought stress, which confers drought tolerance.

Download Full-text

Ectopic Expression of CrPIP2;3, a Plasma Membrane Intrinsic Protein Gene from the Halophyte Canavalia rosea, Enhances Drought and Salt-Alkali Stress Tolerance in Arabidopsis

International Journal of Molecular Sciences ◽

10.3390/ijms22020565 ◽

2021 ◽

Vol 22 (2) ◽

pp. 565

Author(s):

Jiexuan Zheng ◽

Ruoyi Lin ◽

Lin Pu ◽

Zhengfeng Wang ◽

Qiming Mei ◽

...

Keyword(s):

Drought Stress ◽

Transgenic Plants ◽

Osmotic Stress ◽

Stress Tolerance ◽

High Salinity ◽

High Salt ◽

Marker Genes ◽

Transcriptional Level ◽

Wild Type ◽

Ros Scavenging

Aquaporins are channel proteins that facilitate the transmembrane transport of water and other small neutral molecules, thereby playing vital roles in maintaining water and nutrition homeostasis in the life activities of all organisms. Canavalia rosea, a seashore and mangrove-accompanied halophyte with strong adaptability to adversity in tropical and subtropical regions, is a good model for studying the molecular mechanisms underlying extreme saline-alkaline and drought stress tolerance in leguminous plants. In this study, a PIP2 gene (CrPIP2;3) was cloned from C. rosea, and its expression patterns and physiological roles in yeast and Arabidopsis thaliana heterologous expression systems under high salt-alkali and high osmotic stress conditions were examined. The expression of CrPIP2;3 at the transcriptional level in C. rosea was affected by high salinity and alkali, high osmotic stress, and abscisic acid treatment. In yeast, the expression of CrPIP2;3 enhanced salt/osmotic and oxidative sensitivity under high salt/osmotic and H2O2 stress. The overexpression of CrPIP2;3 in A. thaliana could enhance the survival and recovery of transgenic plants under drought stress, and the seed germination and seedling growth of the CrPIP2;3 OX (over-expression) lines showed slightly stronger tolerance to high salt/alkali than the wild-type. The transgenic plants also showed a higher response level to high-salinity and dehydration than the wild-type, mostly based on the up-regulated expression of salt/dehydration marker genes in A. thaliana plants. The reactive oxygen species (ROS) staining results indicated that the transgenic lines did not possess stronger ROS scavenging ability and stress tolerance than the wild-type under multiple stresses. The results confirmed that CrPIP2;3 is involved in the response of C. rosea to salt and drought, and primarily acts by mediating water homeostasis rather than by acting as an ROS transporter, thereby influencing physiological processes under various abiotic stresses in plants.

Download Full-text

Physiological and morphological responses to water stress in Aegilops biuncialis and Triticum aestivum genotypes with differing tolerance to drought

Functional Plant Biology ◽

10.1071/fp03143 ◽

2004 ◽

Vol 31 (12) ◽

pp. 1149 ◽

Cited By ~ 66

Author(s):

István Molnár ◽

László Gáspár ◽

Éva Sárvári ◽

Sándor Dulai ◽

Borbála Hoffmann ◽

...

Keyword(s):

Growth Rate ◽

Triticum Aestivum ◽

Water Stress ◽

Drought Tolerance ◽

Osmotic Stress ◽

Biomass Production ◽

Water Loss ◽

Stomatal Closure ◽

Co2 Assimilation ◽

Wheat Genotypes

The physiological and morphological responses to water stress induced by polyethylene glycol (PEG) or by withholding water were investigated in Aegilops biuncialis Vis. genotypes differing in the annual rainfall of their habitat (1050, 550 and 225 mm year–1) and in Triticum aestivum L. wheat genotypes differing in drought tolerance. A decrease in the osmotic pressure of the nutrient solution from –0.027 to –1.8 MPa resulted in significant water loss, a low degree of stomatal closure and a decrease in the intercellular CO2 concentration (Ci) in Aegilops genotypes originating from dry habitats, while in wheat genotypes high osmotic stress increased stomatal closure, resulting in a low level of water loss and high Ci. Nevertheless, under saturating light at normal atmospheric CO2 levels, the rate of CO2 assimilation was higher for the Aegilops accessions, under high osmotic stress, than for the wheat genotypes. Moreover, in the wheat genotypes CO2 assimilation exhibited less or no O2 sensitivity. These physiological responses were manifested in changes in the growth rate and biomass production, since Aegilops (Ae550, Ae225) genotypes retained a higher growth rate (especially in the roots), biomass production and yield formation after drought stress than wheat. These results indicate that Aegilops genotypes, originating from a dry habitat have better drought tolerance than wheat, making them good candidates for improving the drought tolerance of wheat through intergeneric crossing.

Download Full-text

Drought Stress in Grain Legumes: Effects, Tolerance Mechanisms and Management

Agronomy ◽

10.3390/agronomy11122374 ◽

2021 ◽

Vol 11 (12) ◽

pp. 2374

Author(s):

Marium Khatun ◽

Sumi Sarkar ◽

Farzana Mustafa Era ◽

A. K. M. Mominul Islam ◽

Md. Parvez Anwar ◽

...

Keyword(s):

Drought Stress ◽

Drought Tolerance ◽

Association Studies ◽

Stomatal Closure ◽

Grain Legumes ◽

Grain Legume ◽

Developmental Cycle ◽

Genome Wide Association Studies ◽

Tolerance Mechanisms ◽

Drought Tolerant

Grain legumes are important sources of proteins, essential micronutrients and vitamins and for human nutrition. Climate change, including drought, is a severe threat to grain legume production throughout the world. In this review, the morpho-physiological, physio-biochemical and molecular levels of drought stress in legumes are described. Moreover, different tolerance mechanisms, such as the morphological, physio-biochemical and molecular mechanisms of legumes, are also reviewed. Moreover, various management approaches for mitigating the drought stress effects in grain legumes are assessed. Reduced leaf area, shoot and root growth, chlorophyll content, stomatal conductance, CO2 influx, nutrient uptake and translocation, and water-use efficiency (WUE) ultimately affect legume yields. The yield loss of grain legumes varies from species to species, even variety to variety within a species, depending upon the severity of drought stress and several other factors, such as phenology, soil textures and agro-climatic conditions. Closure of stomata leads to an increase in leaf temperature by reducing the transpiration rate, and, so, the legume plant faces another stress under drought stress. The biosynthesis of reactive oxygen species (ROS) is the most detrimental effect of drought stress. Legumes can adapt to the drought stress by changing their morphology, physiology and molecular mechanism. Improved root system architecture (RSA), reduced number and size of leaves, stress-induced phytohormone, stomatal closure, antioxidant defense system, solute accumulation (e.g., proline) and altered gene expression play a crucial role in drought tolerance. Several agronomic, breeding both conventional and molecular, biotechnological approaches are used as management practices for developing a drought-tolerant legume without affecting crop yield. Exogenous application of plant-growth regulators (PGRs), osmoprotectants and inoculation by Rhizobacteria and arbuscular mycorrhizal fungi promotes drought tolerance in legumes. Genome-wide association studies (GWASs), genomic selection (GS), marker-assisted selection (MAS), OMICS-based technology and CRISPR/Cas9 make the breeding work easy and save time in the developmental cycle to get resistant legumes. Several drought-resistant grain legumes, such as the chickpea, faba bean, common bean and pigeon pea, were developed by different institutions. Drought-tolerant transgenic legumes, for example, chickpeas, are developed by introgressing desired genes through breeding and biotechnological approaches. Several quantitative trait loci (QTLs), candidate genes occupying drought-tolerant traits, are identified from a variety of grain legumes, but not all are under proper implementation. Hence, more research should be conducted to improve the drought-tolerant traits of grain legumes for avoiding losses during drought.

Download Full-text