Transient expression of SbDhr2 and MeHNL in Gossypium hirsutum for herbivore deterrence assay with Spodoptera litura

Journal of Cotton Research

[Background] Spodoptera litura (Lepidoptera: Noctuidae), commonly known as tobacco cutworm or cotton leafworm, is a polyphagous pest which causes considerable damage to cotton (Gossypium hirsutum) and other crops. Herbivore-induced defence response is activated in plants against chewing pests, in which plant secondary metabolites play an important role. Dhurrinase2 (SbDhr2), a cyanogenic β-glucosidase from Sorghum bicolor, is the key enzyme responsible for the hydrolysis of dhurrin (cyanogenic β-glucosidic substrate) to p-hydroxymandelonitrile. Hydroxynitrile lyase (MeHNL) from Mannihot esculanta catalyses the dissociation of cyanohydrins to hydrogen cyanide and corresponding carbonyl compound, both enzymes play a pivotal role in plant defence mechanism.

[Results] SbDhr2 and MeHNL genes were expressed individually and co-expressed transiently in cotton leaves. We examined the feeding response of S. litura to leaves in the choice assay. The Slitura population used in this study showed better feeding deterrence to leaves co-expressing both genes compared with the expression of an individual gene.

[Conclusion] Our results suggest that co-expression of SbDhr2 and MeHNL genes in cotton leaves demonstrate feeding deterrence to S. litura. Engineering cyanogenic pathway in aerial parts of cotton would be an additional defence strategy against generalist pests and can be enhanced against specialist pests.

[Title] Transient expression of SbDhr2 and MeHNL in Gossypium hirsutum for herbivore deterrence assay with Spodoptera litura

[Authors] MAHAJAN Chavi, NASER Rafiuddin & GUPTA Shantikumar

https://doi.org/10.1186/s42397-020-0044-z

https://jcottonres.biomedcentral.com/articles/10.1186/s42397-020-0044-z

Soil replacement combined with subsoiling improves cotton yields

[Background] Long-term rotary tillage has led to the deterioration of cotton production in northern China. This deterioration is due to the disturbance of topsoil, a dense plough pan at the 20–50 cm depth, and the decreased water storage capacity. A 2-yr field experiment was performed from 2014 to 2015 to explore a feasible soil tillage approach to halting the deterioration. The experiment consisted of four treatments: replacing the topsoil from the 0–15 cm layer with the subsoil from the 15–30 cm layer (T1); replacing the topsoil from the 0–20 cm layer with the subsoil from the 20–40 cm layer and subsoiling at the 40–55 cm layer (T2); replacing the topsoil from the 0–20 cm layer with the subsoil from the 20–40 cm layer and subsoiling at the 40–70 cm layer (T3); and conventional surface rotary tillage within 15 cm as the control (CK).

[Results] The results indicated that the soil bulk densities at the 20–40 cm layer in T2 were 0.13 g·cm− 3and 0.15 g·cm− 3 lower than those obtained from CK in 2014 and 2015, respectively. The total nitrogen (N) and the available phosphorus (P) and potassium (K) contents from the 20–40 cm layer in T2 and T3 were significantly higher than those in CK and T1. The amount of soil water stored in the 0–40 cm layer of T2 at the squaring stage of cotton was 15.3 mm and 13.4 mm greater than that in CK in 2014 and 2015, respectively, when the weather was dry. Compared with CK, T2 increased cotton lint yield by 6.1 and 10.2 percentage points in 2014 and 2015, respectively, which was due to the improved roots within the 20–60 cm layer, the greater number of bolls per plant and the higher boll weight in the T2 treatment.

[Conclusions] The results suggested that soil replacement plus subsoiling would be a good alternative to current practices in order to break through the bottleneck constraining cotton production in northern China. Replacing the topsoil in the 0–20 cm layer with the soil from the 20–40 cm layer plus subsoiling at the 40–55 cm layer would be the most effective method.

[Title] Soil replacement combined with subsoiling improves cotton yields

[Authors] LI Pengcheng, WANG Shulin, QI Hong, WANG Yan, ZHANG Qian, FENG Guoyi, ZHENG Cangsong, YU Xueke, LIN Yongzeng & DONG Helin

Journal of Cotton Research2019; 2:25

https://doi.org/10.1186/s42397-019-0038-x

https://jcottonres.biomedcentral.com/articles/10.1186/s42397-019-0038-x

Comparative effects of crop residue incorporation and inorganic potassium fertilization on soil C and N characteristics and microbial activities in cotton field

[Background] Crop residue incorporation into the soil is an effective method to augment soil potassium (K) content, and effects of crop residue and K fertilizer on soil K balance have been compared. However, their influences on other soil characteristics such as carbon (C) and nitrogen (N) characteristics and microbial activities have not been quantified. To address this, field experiments were conducted in 2011 at Dafeng (sandy loam) and Nanjing (clay loam) in China with treatments including blank control without crop residue incorporation and K fertilizer application, 0.9 t·ha− 1 wheat straw incorporation (W1C0), 0.7 t·ha− 1 cotton residue incorporation (W0C1), 0.9 t·ha− 1 wheat straw + 0.7 t·ha− 1 cotton residue incorporation (W1C1) and two K fertilizer rates (150 and 300 kg·ha− 1 (K2O)) during the cotton season.

[Results] Compared with control, K fertilizer treatments did not alter soil water-soluble organic carbon/soil organic carbon (WSOC/SOC) ratio, microbial biomass carbon (MBC)/SOC ratio, MBC/microbial biomass nitrogen (MBN) ratio, water inorganic nitrogen/total nitrogen ratio (WIN/TN), the number of cellulose-decomposing bacteria, or related enzymes activities, however, W0C1, W1C0 and W1C1 treatments significantly increased WSOC/SOC ratio, MBC/SOC ratio and MBC/ MBN ratio, and decreased WIN/TN ratio at both sites. W0C1, W1C0 and W1C1 treatments also increased the number of soil cellulose-decomposing bacteria and activities of cellulase, β-glucosidase and arylamidase. Regarding different crop residue treatments, W1C0 and W1C1 treatments had more significant influences on above mentioned parameters than W0C1 treatment. Moreover, MBC/MBN ratio was the most important factor to result in the differences in the number of cellulose-decomposing bacteria and soil enzymes activities among different treatments.

[Conclusions] This study provided a detailed phenotypic diversity description of a population representing a wide range of upland cotton germplasm. Our findings provide useful information about possible elite fibre quality parents for cotton breeding programs.

[Title] Evaluation of the genetic diversity of fibre quality traits in upland cotton (Gossypium hirsutum L.) inferred from phenotypic variations

[Authors] HU Wei, SUI Ning , YU Chaoran, YANG Changqin, LIU Ruixian and ZHOU Zhiguo

Journal of Cotton Research2019; 2:24

https://doi.org/10.1186/s42397-019-0040-3

https://jcottonres.biomedcentral.com/articles/10.1186/s42397-019-0040-3

Bt insecticidal efficacy variation and agronomic regulation in Bt cotton

Abstract: The bollworm can be controlled effectively with Bacillus thuringiensistransgenic cotton (Bt cotton) which is being applied worldwide. However, the insecticidal efficacy is not stable. Here we give a summary of research progress for the mechanism of the altered insecticidal efficacy, factors affecting the expression of insect resistance, agronomic practices on regulation of insecticidal efficacy in Bt cotton. To realize the transgenic potential of Bt cotton cultivars, future research may be conducted by increasing synthesis and reducing degradation of Bt protein to maintain high insecticidal ability in the transgenic cotton by agronomic management.

[Title] Bt insecticidal efficacy variation and agronomic regulation in Bt cotton

[Authors] LIU Zhenyu, ELTAYIB H M. A. Abidallha, WU Huimin, ZHOU Mingyuan, ZHANG Xiang, CHEN Yuan and CHEN Dehua

Journal of Cotton Research2019; 2:23

https://doi.org/10.1186/s42397-019-0042-1

https://jcottonres.biomedcentral.com/articles/10.1186/s42397-019-0042-1

Evaluation of the genetic diversity of fibre quality traits in upland cotton (Gossypium hirsutum L.) inferred from phenotypic variations

[Background] Evaluating phenotypic traits is very important for the selection of elite lines in Gossypium hirsutum L. Cotton breeders are interested in using diverse genotypes in hybridization that can segregate for traits of interested with the possibility of selection and genetic gain. Information on phenotypic and molecular diversity helps the breeders for parental selection.

[Methods] In this study, 719 global collections of G. hirsutum L. were evaluated for five fibre-related traits during two consecutive years in eight different environments. A series of phenotypic data for fibre quality traits were obtained and the elite accessions were further screened using principal component analysis and phylogenetic tree construction based on single nucleotide polymorphism markers.

[Results] We found that fibre quality traits showed a wide range of variation among the G. hirsutum accessions over 2 years. In general, accessions from outside China tended to have higher fibre length (FL) and fibre strength (FS) than did Chinese accessions. Among different regional accessions in China, North/Northwest accessions tended to have the highest FL, FS and best fibre macronaire. By assessing five fibre quality traits over 2 years with genotypic data, 31 elite germplasms reaching double-thirty quality values (FL ≥ 30 mm and FS ≥ 30 cN·tex− 1) were selected.

[Conclusions] This study provided a detailed phenotypic diversity description of a population representing a wide range of upland cotton germplasm. Our findings provide useful information about possible elite fibre quality parents for cotton breeding programs.
[Title] Evaluation of the genetic diversity of fibre quality traits in upland cotton (Gossypium hirsutum L.) inferred from phenotypic variations

[Authors] SUN Zhengwen, WANG Xingfen, LIU Zhengwen, GU Qishen, ZHANG Yan, LI Zhikun, KE Huifeng, YANG Jun, WU Jinhua, WU Liqiang, ZHANG Guiyin and MA Zhiying
Journal of Cotton Research2019; 2:22

https://doi.org/10.1186/s42397-019-0041-2

https://jcottonres.biomedcentral.com/articles/10.1186/s42397-019-0041-2

Towards improving drought resistance and lodging resistance in cotton

Abstract: Cotton is one of the most important fiber and oil crop in the world and the fiber yield as well as quality traits are negatively affected by drought and lodging. Improving root gravitropism is a very effective way to enhance the crop resistance to drought and lodging stresses. Recent advance in origin and formation of root gravitropism may provide new insights to increase drought and lodging resistance in cotton.

[Title] Towards improving drought resistance and lodging resistance in cotton

[Authors] LI Fuguang

Journal of Cotton Research2019; 2:21
https://doi.org/10.1186/s42397-019-0037-y
https://jcottonres.biomedcentral.com/articles/10.1186/s42397-019-0037-y

Large-scale inversions majorly drive upland cotton population differentiation

Journal of Cotton Research

Abstract: Recently, Li and his team hosted a project on roles of inversion in upland cotton population differentiation. Strikingly, genomic comparison identified, and subsequent RIL population and germplasm panel haplotype analyses confirmed, that large-scale inversions on chromosome At08 are widely distributed and have over time mediated the reduction of meiotic recombination that has ultimately driven genetically isolated haplotypes of G. hirsutum. This work is likely to become the new benchmark for cotton functional genomics research, and the scientific insights from the comparative analyses contributed substantially to our basic understanding of how genomic inversions influence meiotic recombination and thus lower genetic diversity in plant populations.

[Title] Large-scale inversions majorly drive upland cotton population differentiation

[Authors] TIAN Shilin &MA  Zhiying

Journal of Cotton Research2019; 2:20
https://doi.org/10.1186/s42397-019-0037-y
https://jcottonres.biomedcentral.com/articles/10.1186/s42397-019-0037-y

Down regulation of cotton GbTRP1 leads to accumulation of anthranilates and confers resistance to Verticillium dahliae

Journal of Cotton Research

[Background] Verticillium wilt, caused by Verticillium dahliae, is called a “cancer” disease of cotton. The discovery and identification of defense-related genes is essential for the breeding of Verticillium wilt-resistant varieties. In previous research we identified some possible broad-spectrum resistance genes. Here, we report a tryptophan synthesis-related gene GbTRP1 and its functional analysis in relation to the resistance of cotton to V. dahliae.

[Results] Expression analysis shows that GbTRP1 is suppressed at 1 h and 6 h post V. dahliae infection, but activated at 12 h and 24 h, and the expression of GbTRP1 is highly induced by treatment with salicylic acid and jasmonic acid. Sub-cellular localization studies show that GbTRP1 is localized in the chloroplast. Suppression of GbTRP1 expression leads to lesion-mimic phenotypes and activates the immune response in cotton by showing enhanced resistance to V. dahliae and B. cinerea. Metabolomic analysis shows that anthranilic compounds significantly accumulated in GbTRP1-silenced plants, and these metabolites can inhibit the growth of V. dahliae and B. cinerea in vitro.

[Conclusions] Our results show that suppression of GbTRP1 expression dramatically activates the immune response and increases resistance of cotton to V. dahliae and B. cinerea, possibly due to the accumulation of anthranilate compounds. This study not only provides genetic resources for disease resistance breeding, but also may provide a basis for new chemical control methods for combatting of fungal disease in cotton.

[Title] Down regulation of cotton GbTRP1 leads to accumulation of anthranilates and confers resistance to Verticillium dahliae

[Authors] MIAO Yuhuan, ZHU Longfu and ZHANG Xianlong

Journal of Cotton Research. 2019; 2:19

https://doi.org/10.1186/s42397-019-0034-1

https://jcottonres.biomedcentral.com/articles/10.1186/s42397-019-0034-1

High-throughput phenotyping in cotton: a review

Abstract

Recent technological advances in cotton (Gossypium hirsutum L.) phenotyping have offered tools to improve the efficiency of data collection and analysis. High-throughput phenotyping (HTP) is a non-destructive and rapid approach of monitoring and measuring multiple phenotypic traits related to the growth, yield, and adaptation to biotic or abiotic stress. Researchers have conducted extensive experiments on HTP and developed techniques including spectral, fluorescence, thermal, and three-dimensional imaging to measure the morphological, physiological, and pathological resistance traits of cotton. In addition, ground-based and aerial-based platforms were also developed to aid in the implementation of these HTP systems. This review paper highlights the techniques and recent developments for HTP in cotton, reviews the potential applications according to morphological and physiological traits of cotton, and compares the advantages and limitations of these HTP systems when used in cotton cropping systems. Overall, the use of HTP has generated many opportunities to accurately and efficiently measure and analyze diverse traits of cotton. However, because of its relative novelty, HTP has some limitations that constrains the ability to take full advantage of what it can offer. These challenges need to be addressed to increase the accuracy and utility of HTP, which can be done by integrating analytical techniques for big data and continuous advances in imaging.

Authors:

PABUAYON Irish Lorraine B., SUN Yazhou, GUO Wenxuan & RITCHIE  Glen L.

 

Journal of Cotton Research2019; 2:18

https://doi.org/10.1186/s42397-019-0035-0

https://jcottonres.biomedcentral.com/articles/10.1186/s42397-019-0035-0

Comparative transcriptional analysis provides insights of possible molecular mechanisms of wing polyphenism induced by postnatal crowding in Aphis gossypii

Background
Aphis gossypii is a worldwide sap-sucking pest with a variety of hosts and a  vector of more than 50 plant viruses. The strategy of wing polyphenism, mostly resulting from population density increasing, contributes to the evolutionary success of this pest. However, the related molecular basis remains unclear. Here, we identified the effects of postnatal crowding on wing morph determination in cotton aphid, and examined the transcriptomic differences between wingless and wing morphs.

Results
Effect of postnatal crowding on wing determination in A. gossypii was evaluated firstly. Under the density of 5 nymphs·cm− 2, no wing aphids appeared. Proportion of wing morphs rised with the increase of density in a certain extent, and peaked to 56.1% at the density of 20 nymphs·cm− 2, and reduced afterwards. Then, transcriptomes of wingless and wing morphs were assembled and annotated separately to identify potentially exclusively or differentially expressed transcripts between these two morphs, in which 3 126 and 3 392 unigenes annotated in Nr (Non-redundant protein sequence) database were found in wingless or wing morphs exclusively. Moreover, 3 187 up- and 1 880 down-regulated genes were identified in wing versus wingless aphid. Pathways analysis suggested the involvement of differentially expressed genes in multiple cellular signaling pathways involved in wing morphs determination, including lipid catabolic and metabolism, insulin, ecdysone and juvenile hormone biosynthesis. The expression levels of related genes were validated by the reverse transcription quantitative real time polymerase chain reaction (RT-qPCR) soon afterwards.

Conclusions
The present study identified the effects of postnatal crowding on wing morphs induction and demonstrated that the critical population density for wing morphs formation in A. gossypii was 20 nymphs·cm− 2. Comparative transcriptome analysis provides transcripts potentially expressed exclusively in wingless or wing morph, respectively. Differentially expressed genes between wingless and wing morphs were identified and several signaling pathways potentially involved in cotton aphid wing differentiation were obtained.

Authors:

JI Jichao, ZHANG Shuai, LUO Junyu, WANG Li, ZHU Xiangzhen, ZHANG Kaixin, ZHANG Lijuan & CUI Jinjie

Journal of Cotton Research. 2019,2:17

https://doi.org/10.1186/s42397-019-0036-z