15 September 2018, Volume 30 Issue 5

    

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  Transgenic Cotton Expressing Double-Stranded RNAs of AgATPase Subunit E Gene Increases Resistance to Aphids

  Luo Xiaoli, Zhang Anhong, Xiao Juanli, Wang Zhi’an, Chen Xiaoying, Wu Jiahe

  Cotton Science. 2018, 30(5): 353-362. https://doi.org/10.11963/1002-7807.lxlwjh.20180723

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  [Objective] The cotton aphid (Aphis gossypii) seriously affects cotton growth and development. Recently, RNA interference (RNAi) technology has been employed as a new technique to control damage caused by agricultural pests. There is an urgent demand to develop transgenic cotton expressing double stranded RNA (dsRNA) targeting insect essential genes to control damage by aphids. [Method] In this study, we isolated a gene that encodes adenosine triphosphatase (ATPase) subunit E from the cotton aphid, and constructed a plant RNAi expression vector with the fragment of this gene. The transgenic cotton plants were developed through Agrobacterium-mediated transformation. The putative transgenic plants were screened by polymerase chain reaction (PCR) analysis, and the PCR-positive transgenic plants were subjected to Southern blot assay to detect the copy number of T-DNA insertions. Then, reverse transcription PCR (RT-PCR) was employed to analyze the expression level of dsRNA. [Result] Twenty-two transgenic plants were confirmed from 45 putative transgenic plants. The dsRNA had been introduced into the cotton genome with a single- or multi-copy insertion. Among the 22 transgenic plants, 12 plants contained only one copy of T-DNA, which had been stably expressed in cotton cells. The four transgenic lines, CZ1, CZ2, CZ3, and CZ4, with one- or two-copy dsRNA insertions and obviously normal agricultural traits were selected for analysis of aphid resistance. According to identification of aphid resistance in both net room and field experiments, the results showed that the CZ1, CZ2 and CZ3 transgenic lines possessed high toxicity against cotton aphids, with over 70% and 60% decline rates of aphid damage in 2015 and 2016, respectively, while the control exhibited susceptibility to aphids, leading to leaf curl and stunted growth. [Conclusion] The cotton aphid resistance in transgenic cotton plants with the fragment of aphid ATPase subunit E gene by RNAi provides a new idea, method and germplasm for aphid-resistant breeding.
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  Analysis of Community Structure and Diversity of Endophytic Fungi from Cotton in Different Areas of Shandong Province

  Song Haiyan, Li Lili, Lu Zengbin, Yu Yi, Zhang Ansheng, Zhuang Qianying, Zhou Xianhong, Men Xingyuan

  Cotton Science. 2018, 30(5): 363-374. https://doi.org/10.11963/1002-7807.shymxy.20180930

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  [Objective] Endophytic fungi can promote plant growth and enhance plant resistance to adverse environments. This article analyzed the community structure, biodiversity and distribution of endophytic fungi from cotton plants, and discusses the potential relationship between endophytic fungi community structure and biodiversity and the growing environment. [Method] Cotton leaves were collected from 19 areas in Shandong province, China. The endophytic fungi were isolated, purified and conserved with potato dextrose agar medium. After identification by internal transcribed spacers, the community structure and diversity were analyzed. [Result] The results showed that 134 strains and 15 genera (Alternaria, Fusarium, Diaporthe, Penicillium, Stemphylium, Bipolaris, Epicoccum, Curvularia, Nigrospora, Botryosphaeria, Lichtheimia, Gibellulopsis, Phaeosphaeria, Cladosporium, Setosphaeria) were obtained. Alternaria (77.12%) was the dominant genus of endophytic fungi in Shandong province. Fusarium was the dominant genus in the Bincheng district of Binzhou (66.67%), and Huantai (100.00%), while Alternaria (50.00%) and Fusarium (50.00%) were the dominant genera of Caoxian, and Alternaria (37.50%) and Setosphaeria (37.50%) were the dominant genera of Jiyang. There were significant differences in the colonization rate in different areas. The highest colonization rate appeared in Kenli (85%), followed by Chiping (85%) and Wudi (60%), while the lowest colonization rate appeared in Huimin and Zoucheng (5%). According to the Shannon-Weaver index, Jiyang had the highest diversity index (1.26), followed by Chiping (1.15), the Bincheng district in Binzhou (0.87), Caoxian (0.69), Yuncheng (0.64), Wudi (0.59), Kenli (0.57), Jinxiang (0.51), and Shanghe (0.35). Only single genera, Alternaria, were found in each of  the locations Chengwu, Dong'e, Gaotang, Huimin, the Dongchangfu district in Liaocheng, Xiajin, Yanggu, Yutai, Zoucheng and Huantai. Cluster analysis showed that the 19 geographic areas could be classified into two groups. One group included Chiping, Wudi and Kenli, which had a higher colonization rate and more genera; the other one had a lower colonization rates and fewer genera. [Conclusions] The endophytic fungi in cotton were highly diverse. The distributions of endophytic fungi were distinct among regions in Shandong province.
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  The Control Effect and Mechanism of Concentrated Biogas Slurry on Verticillium Wilt of Upland Cotton

  Feng Zili, Dong Taili, Zhao Lihong, Fu Chuancui, Li Yunqing, Shi Yongqiang, Feng Hongjie, Wei Feng, Zhang Dongming, Zhu Heqin

  Cotton Science. 2018, 30(5): 375-385. https://doi.org/10.11963/1002-7807.fzlzhq.20181008

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  [Objective] This study investigated the effect of concentrated biogas slurry on Verticillium wilt of cotton (Gossypium hirsutum) and determine the mechanism of any observed impacts. [Method] The inhibition rate of concentrated biogas slurry against Verticillium dahliae was assessed using the mycelium growth rate method, concave slide method and hanging drop method. The effect on controlling cotton Verticillium wilt was detected by foliage spray and irrigation in pot experiments. Induced disease resistance of concentrated biogas slurry in cotton was analyzed by reactive oxygen species (ROS). In addition, the expression levels of defense genes in G. hirsutum leaves were detected by reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR). [Result] The results showed that colony growth, conidial yield and microsclerotia germination of the pathogen were significantly inhibited by the concentrated biogas slurry. The volatile organic compounds of the concentrated biogas slurry may have caused the mycelium hyphae to become malformed and broken. In the greenhouse, a 0.50% (volume fraction) dilution of concentrated biogas slurry via two foliage spray treatments significantly reduced the disease index, with the control efficacy of 64.89%. 1.25% concentrated biogas slurry applied via two pouring root treatments significantly reduced the disease index, with a control efficacy of 78.01%. In the severely diseased nursery, 120 L·hm-2 was the optimal dosage of concentrated biogas slurry for controlling Verticillium wilt by drip irrigation. Concentrated biogas slurry was also shown to enhance disease resistance response of cotton plants, including ROS and some defense genes that encodes peroxidase, chitinase, β-1,3-glucanase, phenylalanine ammonia lyase, cadinene synthase and polyphenol oxidase. All these genes may play important roles in inhibiting pathogen growth and dispersion within cotton plants. [Conclusion] Concentrated biogas slurry can effectively control Verticillium wilt in cotton; the action mechanisms against the pathogen may include direct suppression and enhanced resistance of host plants.
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  Effect of Irrigation Patterns on Accumulation and Distribution of Dry Matter, Yield and Water Use Efficiency of Cotton in Southern Hebei

  Xu Ruibo, Sun Hongchun, Liu Liantao, Zhang Yongjiang, Liu Yuchun, Bai Zhiying, Li Cundong

  Cotton Science. 2018, 30(5): 386-394. https://doi.org/10.11963/1002-7807.xrblcd.20180929

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  [Objective] This study examines how irrigation patterns affect soil moisture, growth and yield of cotton in southern Hebei, China. The results are used to inform irrigation patterns and improve the water use efficiency of cotton. [Method] Using the Nongda 601 cotton variety, a field split plot experiment was conducted in 2016 and 2017. The main treatments were no film (NF) and mulching film (MF), with side treatments of border irrigation (W1, 600 m³·hm^-2), limited amount every-other furrow irrigation I (W2, 450 m³·hm^-2) and limited amount every-other furrow irrigation II (W3, 300 m³·hm^-2). Six treatments NFW1, NFW2, NFW3, MFW1, MFW2, and MFW3 were applied. The film-covered border irrigation represents the conventional cultivation mode of local cotton. Impacts were measured as dry matter mass, yield and water use efficiency. [Result] (1) Dry matter mass of MF was significantly higher than that of NF in 2016 and 2017. However, there was no significant difference in different irrigation treatments under MF. When compared with the dry matter mass of NFW1 in 2016, that of NFW2 and NFW3 were significantly lower: by 14.28% and 13.44%, respectively. In 2017, the dry matter quality of NFW2 significantly increased by 11.29% compared with that of NFW1, but NFW3 showed no significant difference. (2) Cotton yield and water use efficiency showed similar trends in both years. There was no significant difference in yield and water use efficiency for the different irrigation treatments under MF. Compared with NFW1, NFW2 and NFW3 significantly decreased by 10.21%–16.00% and 13.63%–18.84% in yield, respectively, whereas water use efficiency significantly decreased by 8.33%–13.80% and 9.72%–14.61%, respectively. Compared with MFW1, yield and water use efficiency of NFW1 decreased slightly, but not significantly. Compared with MFW2, yield and water use efficiency of NFW2 significantly decreased 12.96%–16.62% and 13.73%–16.51%, respectively. Compared with MFW3, yield and water use efficiency of NFW3 significantly decreased 15.04%–16.29% and 15.03%–16.31%, respectively. [Conclusion] In wet and normal precipitation years, the NFW1 treatment resulted in high cotton yield while preventing residual film pollution; MFW2 and MFW3 treatments also achieved high yields and improved water use efficiency when irrigation quantity was reduced.
  
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  Effect of Drip Irrigation under Film on Soil Water and Salt Movement in a Residual Film Cotton Field

  Wu Fengquan, Lin Tao, Wang Jing, Wang Liang, Yan Changrong, Zumilaiti Tuergan Deng Fangning, Er Chen, Tang Qiuxiang

  Cotton Science. 2018, 30(5): 395-405. https://doi.org/10.11963/1002-7807.wfqlt.20180904

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  [Objective] This study explores the effect of mulching film residue on the spatial and temporal distribution of soil water and salt in a cotton field under drip irrigation. [Method] Three treatments of 0 kg·hm^-2, 225 kg·hm^-2 and 450 kg·hm^-2 residual mulching film were applied. Soil salt content was measured and the difference between the mulching treatments was analyzed using a soil drilling method to delaminate 0–40 cm soil before cotton sowing, after harvesting and on days 1, 3 and 5 after watering during the blooming period. [Result] The results showed that residual mulching film reduced soil moisture uniformity in the drip irrigated cotton field. An uneven distribution of salt in different soil layers was also observed after irrigation. The soil salinity of the 0 kg·hm^-2 residual film treatment decreased in each soil layer over time, while the soil salinity of the 225 kg·hm^-2 and 450 kg·hm^-2 treatments decreased 1 and 3 days after irrigation, but then increased 5 days after irrigation (non-significant difference). With respect to distribution of soil salinity following irrigation, uniformity in the 0 kg·hm^-2 residual film treatment was best, followed by the 450 kg·^hm-2 treatment and the 225 kg·hm^-2 treatment. The effect of residual mulching film on soil salinity balance before and after sowing of cotton was as follows: 250 kg·hm^-2 > 450 kg·hm^-2 > 0 kg·hm^-2. As the depth of the residual film increased, the enrichment of soil salts in the topsoil was more likely to occur. [Conclusion] It can be concluded that residual mulching film hinders the downward migration of soil salinity. Under conditions of elevated residual mulching film, the soil salinity migration is disrupted to the degree that soil salt enrichment occurs at the soil surface.
  
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  Short-Season Cotton: Mechanism of Early Maturity and its Cultivation

  Qi Jie, Dai Jianlong Sun Xuezhen, Dong Hezhong

  Cotton Science. 2018, 30(5): 406-413. https://doi.org/10.11963/1002-7807.qjdhz.20180916

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  Short-season cotton varieties are characterized by a short period of growth and development, a rapid development process and relatively concentrated flowering and boll-setting. Consequently, short-season cotton can reach early maturity with late sowing. In this paper, the morphological characteristics as well as the physiological and molecular biological mechanisms of early maturity on short-season cotton are reviewed. The characteristics of short-season cotton with regard to optimizing planting patterns and methods, promoting cultivation of cotton in saline-alkaline fields, developing machine-harvested cotton and planting cotton without plastic mulching are also discussed. On the basis of these characteristics, future strategies are proposed for improving breeding and cultivation of short-season cotton.
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  Review of Field Bindweed, Convolvulus arvensis L., a Troublesome Weed in Cotton Fields

  Cotton Science. 2018, 30(5): 414-422. https://doi.org/10.11963/1002-7807.wymxy.20180919

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  Field bindweed(Convolvulus arvensis L.), known as one of the ten most noxious weeds in the world, has a considerable ability to adapt to the environment and to reproduce and regenerate. In recent decades, field bindweed has increasingly become a problematic weed of cotton fields in China. This review summarizes research to-date on this weed, including morphological and taxonomic characteristics, distribution and habitat, life history, economic characteristics and control strategy. Based on the analysis of the occurrence and harmfulness of field bindweed in China, we suggest carrying out further research on the reproductive characteristics of perennial root systems, adaptability to regional environments and high-efficiency control technologies for field bindweed.