Gene Co-Expression Analysis Reveals Transcriptome Divergence between Wild and Cultivated Sugarcane under Drought Stress

Drought is the main abiotic stress that constrains sugarcane growth and production. To understand the molecular mechanisms that govern drought stress, we performed a comprehensive comparative analysis of physiological changes and transcriptome dynamics related to drought stress of highly drought-resistant (ROC22, cultivated genotype) and weakly drought-resistant (Badila, wild genotype) sugarcane, in a time-course experiment (0 h, 4 h, 8 h, 16 h and 32 h). Physiological examination reviewed that ROC22, which shows superior drought tolerance relative to Badila, has high performance photosynthesis and better anti-oxidation defenses under drought conditions. The time series dataset enabled the identification of important hubs and connections of gene expression networks. We identified 36,956 differentially expressed genes (DEGs) in response to drought stress. Of these, 15,871 DEGs were shared by the two genotypes, and 16,662 and 4423 DEGs were unique to ROC22 and Badila, respectively. Abscisic acid (ABA)-activated signaling pathway, response to water deprivation, response to salt stress and photosynthesis-related processes showed significant enrichment in the two genotypes under drought stress. At 4 h of drought stress, ROC22 had earlier stress signal transduction and specific up-regulation of the processes response to ABA, L-proline biosynthesis and MAPK signaling pathway–plant than Badila. WGCNA analysis used to compile a gene regulatory network for ROC22 and Badila leaves exposed to drought stress revealed important candidate genes, including several classical transcription factors: NAC87, JAMYB, bHLH84, NAC21/22, HOX24 and MYB102, which are related to some antioxidants and trehalose, and other genes. These results provide new insights and resources for future research and cultivation of drought-tolerant sugarcane varieties.

Seleksi Mutan Tanaman Lamtoro (Leucaena leucocephala cv. Tarramba) Tahan Kutu Loncat terhadap Lingkungan Kering pada Rumah Kaca

Forage is the main source of feed for ruminants. Forage consists of two types, namely grass and legumes. Leguminosa is a type of forage as a source of protein. One type of legume that is well known by breeders in Indonesia is lamtoro (Leucaena leucocephala cv. Tarramba). This study was aimed to produce candidate mutants of lamtoro drought resistant to acid stress conditions. The experiment in this study used an unbalanced completely randomized design with 6 treatments of 740 different replications based on different sources of lamtoro plant mutants at different levels (P0: 0 n= 89, P1: 100 gy n= 82, P2: 200 gy n= 153, P3:300 gy n=120, P4: 400 gy n= 244, P5: 500 gy n= 52). Variables observed included plant height, number of stalks, leaf loss and stem diameter. The results showed that lamtoro plants irradiated with gamma rays at a level of 200 gy-500 gy were significantly higher than 100 gy irradiation at 10 and 12 days watering, but the diameter of the plants was larger at 100 gy irradiation. It can be watering intervals of 10 days and 12 days on the parameters of height and stem diameter showed that gamma rays irradiation of 400 gy resulted in dry-resistant lamtoro mutant candidates under acid stress condition. Key words: gamma rays, lamtoro mutant, watering interval

Collection of the genus Cotinus Mill. in the National dendrological park “Sofiyivka” of NAS of Ukraine

Intr0ducti0n. Green plantations in Ukraine require optimization of species, shape and varietal composition of ornamental plants. These include the genus Cotinus Mill. one of the oldest genera of angiosperms of the Sumac family (Anacardiaceae Lindl.). Matcrials and mcth0ds. The species and varietal composition of the Cotinus collection of the Sofiyivka National Dendrological Park of the National Academy of Sciences of Ukraine was studied. Morphological fea- tures of collectibles of the genus Cotinus were studied according to generally accepted methods. Rcsults and discussi0n. In he collection of the National Arboretum “Sofiyivka” of the National Academy of Sciences of Ukraine two species and 4 cultivars of the genus Cotinus were tested and studied, namely: C. obovatus Raf., C. coggygria Scop., C. coggygria ‘Royal Purple’, C. coggygria ‘Purpureus’, C. coggygria ‘Young Lady, C. coggygria ‘Golden Spirit’. According to our research, all members of the genus Cotinus winter-, frost-resistant, as well as drought-resistant plants. They have satisfactory growth and bloom and bear fruit annually. C0nclusi0ns. Thus, the collection of plants of NDP “Sofiyivka” includes a valuable fund of genetic resources of the genus Cotinus, which is used mainly as a mother plant for the reproduction of ornamental forms that are in demand in the market of seedlings.

Evaluation of Drought Tolerance in Maize Inbred Lines Selected from the Shaan A Group and Shaan B Group

Drought is one of the most prevailing abiotic stresses affecting the growth, development, and productivity of maize. Knowledge of drought tolerance could help in maize improvement. However, less research has been done to comprehensively evaluate the drought tolerance of maize inbred lines. We used 27 elite maize inbred lines selected from Shaan A group and Shaan B group breeding populations to estimate their drought tolerance in 3 years 2 locations under normal field conditions and low irrigation. Using principal component analysis (PCA) and GGE biplots, all inbred lines, including the controls, could be divided into four types. Ten lines could be categorized as the high-yield drought-resistant type (‘KB081’, ‘KA105’, ‘KB417’, ‘KB215’, ‘KB-7’, ‘2013KB-37’, ‘KA203’, ‘2012KA-34’, ‘KA225’, and ‘91227’) because of their stability and wide adaptability. Compared with the controls, a large proportion of the inbred lines selected from Shaan A and Shaan B breeding populations demonstrated higher drought resistance. Our results suggest that multi-year drought screening can be used as a tool to improve the drought resistance of maize inbred lines and provide a scientific basis for making better use of the Shaan A and Shaan B maize inbred lines to breed new varieties and to identify existing drought-resistant maize varieties.

Climate change adaptation strategies and production efficiency: The case of citrus farmers in the Limpopo province, South Africa

Climate change adaptation policies and strategies have inevitably become an integral component of agricultural production on a global scale. The evaluative extent to which these adaptation techniques have influenced agricultural productivity is inherently exiguous. Citrus production in tropical regions such as South Africa, is more vulnerable to climate change as the region already experience hot and dry climate, hence the need to implement different strategies for climate change adaption in these regions. This study was designed to assess the effect of adopting the following climate change adaptation measures: planting drought resistant varieties, rainwater harvesting, planting early maturing varieties, integrated pest management (IPM) , changing fertiliser type, and applying drip irrigation to manage climate challenges on the production efficiency of citrus farmers in the Limpopo province of South Africa. The stochastic frontier production function with Cobb Douglas production functional form was used to analyse the productivity of farmers’ vis-à-vis adopted climate change strategies. A survey was conducted and data were collected through a semi-structured questionnaire administered to respondents from 235 production units in the five district municipalities of Limpopo. The likelihood ratio tests for profit models showed that farmers were profit efficient considering the identified adaptation strategies. The variables that influenced profit efficiency was price of fertiliser (p 0.010) and water cost (p 0.010). The inefficiency model showed that besides changing fertiliser as an adaptation measure, the other adaptation strategies including IPM, water harvesting and planting drought resistant varieties did not change the profit efficiency of farmers. Therefore, the results indicate that citrus farmers can still adapt to climate change and remain profit efficient.

Uncoupling differential water usage from drought resistance in a dwarf Arabidopsis mutant

Understanding the molecular and physiological mechanisms of how plants respond to drought is paramount to breeding more drought resistant crops. Certain mutations or allelic variations result in plants with altered water-use requirements. To correctly identify genetic differences which confer a drought phenotype, plants with different genotypes must therefore be subjected to equal levels of drought stress. Many reports of advantageous mutations conferring drought resistance do not control for soil water content variations across genotypes and may therefore need to be re-examined. Here, we reassessed the drought phenotype of the Arabidopsis thaliana dwarf mutant, chiquita1-1 (also called cost1), by growing mutant seedlings together with the wild type to ensure uniform soil water availability across genotypes. Our results demonstrate that the dwarf phenotype conferred by loss of CHIQ1 function results in constitutively lower water usage, but not increased drought resistance.

Screening for Drought Tolerance through Root Morphology and Yield Characters of Groundnut (Arachis hypogaea L.) Genotypes

Drought affects the rainfed groundnut (Arachis hypogaea L.) at different phases of development and it is the serious threats on groundnut productivity causing losses than any other abiotic factor under rainfed agriculture. In the world's semiarid regions, groundnut accounts for 90% of worldwide production. Drought mainly affects the pace and pattern of nutrient and water intake from the soil, affecting the architecture of the groundnut root system. Plant selections with desirable root trait have been a major focus in developing drought resistant Groundnut cultivars. In 2019, 60 groundnut genotypes were cultivated in root block design with two different soil water treatments, as well as in the field during the year under same circumstances. The purpose of this study was to see how different groundnut cultivars fared in terms of yield, yield contributing features, root characters, and their relationships with drought tolerance. Drought resistant genotypes had thicker roots, larger roots, and a deeper root system than susceptible genotypes. Recent series in groundnut genotypes of 60 numbers were sown during kharif 2019 (july-september) under rainfed condition (It includes life irrigation and rainfall received during cropping season). Groundnut genotypes were semi spreading with the duration of 110-120 days. Observation on root morphological character viz., roots length, root volume after 20 days of stress imposition of the crop and yield parameters were observed at the harvest. Among the 60 genotypes, 20 genotypes (VG 17008, VG 17046, VG 18005, VG 18102, VG 18077, VG 19572, VG 19709, VG 18111, VG19561, VG19576, VG 19620, VG 19681, VG 19688 etc.,) similarly, yield character were observed for 60 genotypes and all the genotypes given above recorded higher value in Total number of pods per plant, Number of double seeded pods per plant, Pod yield per plant, Harvest index and Total dry matter production. The methods used in this study identified correlation between yield character and root characters. Groundnut genotypes by assessing yield metrics and their relationship with root trait. These findings lay the groundwork for future study aimed at deciphering the molecular pathways underpinning Groundnut drought resistance.

Whole transcriptome sequencing reveals drought resistance-related genes in upland cotton

China, especially the Xinjiang cotton area, is facing severe agricultural water shortages, which seriously restrain the development of the cotton industry. Discovering cotton drought resistance genes and cultivating high-quality and drought-resistant cotton materials through molecular breeding methods are of great significance to the development of the cotton industry. In this study, the drought-resistant cotton material Xinluzhong NO.82 and the drought-sensitive cotton material Kexin NO.1 were used to identify a batch of drought-resistant candidate genes through whole transcriptome sequencing. The main research results obtained were as follows: the ceRNA (competing endogenous RNAs) network was constructed using full transcriptional sequencing to screen the core genes in the core pathway; two drought-related candidate genes were obtained. Gohir.A11G156000 was upregulated at 0 h vs 12 h and downregulated at 12 h vs 24 h. Gohir.A07G220600 was downregulated at 0 h vs 12 h and upregulated at 12 h vs 24 h. The results for drought-resistant materials and drought-sensitive materials were similar. Gohir.A11G156000, encoding GABA-T, which is homologous to POP2 in Arabidopsis thaliana, affects the drought resistance of plants by regulating the GABA content. Gohir.A07G220600 encodes L-aspartate oxidase, which is homologous to AO in Arabidopsis thaliana, and is involved in the early steps of NAD biosynthesis and in plant antioxidant reactions. This study confirmed that the use of gene expression regulatory networks can quickly screen reliable drought-resistance genes and can be used for subsequent gene function verification.