Evaluation of genetic diversity in short duration cotton (Gossypium hirsutum L.)

[Background] Cotton (Gossypium hirsutum L.) is an important fiber crop in Bangladesh. Genetic diversity among the genotypes of a germplasm has a great importance for cotton breeding. An experiment was carried out at the experimental field of Cotton Research, Training and Seed Multiplication Farm, Sreepur, Gazipur during the cropping season of 2015–2016 with 100 genotypes to evaluate genetic diversity of cotton genotypes for short duration using field performance.

[Results] The genotypes under study were grouped into ten clusters through multivariate analysis using GENSTAT-5. Cluster III contained maximum number of genotypes (16) while cluster X contained the least number of genotypes (7). The inter cluster distances were larger than intra cluster distances in all cases suggesting wider genetic diversity among the genotypes of different clusters. The maximum and minimum inter cluster distances were observed between clusters II and V (10.78) and clusters VIII and IX (3.30), respectively. The results indicated diverse and close relationship among the genotypes of those clusters. Earliness index, single boll weight and days to boll opening showed the higher contribution to the genetic divergence among 19 characters.

[Conclusion] Based on the results of genetic diversity and earliness index, the genotypes from cluster II could be used as parent in hybridization program for the development of short duration cotton variety.

Evaluation of genetic diversity in short duration cotton (Gossypium hirsutum L.)

AKTER T., ISLAM A. K. M. A., RASUL M. G., KUNDU S., KHALEQUZZAMAN and AHMED J. U.
Journal of Cotton Research. 2019; 2:1.
https://doi.org/10.1186/s42397-018-0018-6

Genetic diversity and population structure of Gossypium arboreum L. collected in China

[Background] Gossypium arboreum is a diploid species cultivated in the Old World. It possesses favorable characters that are valuable for developing superior cotton cultivars.

[Method] A set of 197 Gossypium arboreum accessions were genotyped using 80 genome-wide SSR markers to establish patterns of the genetic diversity and population structure. These accessions were collected from three major G. arboreum growing areas in China. A total of 255 alleles across 80 markers were identified in the genetic diversity analysis.

[Results] Three subgroups were found using the population structure analysis, corresponding to the Yangtze River Valley, North China, and Southwest China zones of G. arboreum growing areas in China. Average genetic distance and Polymorphic information content value of G. arboreum population were 0.34 and 0.47, respectively, indicating high genetic diversity in the G. arboreum germplasm pool. The Phylogenetic analysis results concurred with the subgroups identified by Structure analysis with a few exceptions. Variations among and within three groups were observed to be 13.61% and 86.39%, respectively.

[Conclusion] The information regarding genetic diversity and population structure from this study is useful for genetic and genomic analysis and systematic utilization of economically important traits in G. arboreum.

Genetic diversity and population structure of Gossypium arboreum L. collected in China
JIA Yinhua, PAN Zhaoe, HE Shoupu, GONG Wenfang, GENG Xiaoli, PANG Baoyin, WANG Liru and DU Xiongming
Journal of Cotton Research. 2018; 1:11.
https://doi.org/10.1186/s42397-018-0011-0

Map-based cloning of a recessive gene v1 for virescent leaf expression in cotton (Gossypium spp.)

[Background] Virescence, as a recognizable phenotype in the early development stage of cotton, is not only available for research on chloroplast development and photosynthesis but also for heterosis exploitation in cotton.

[Methods] In current study, for fine mapping of virescent-1 (v1) in cotton, three populations with a total of 5 678 individuals were constructed using T582 which has the virescent trait. Tobacco rattle virus, TRV1 and TRV2 (pYL156), were used as vectors for the virus-induced gene silencing (VIGS) assay.

[Results] The v1 gene was fine-mapped to a 20 kb interval on chromosome 20 of tetraploid cotton. We identified only one candidate gene with four single nucleotide polymorphisms between parents, among which the single nucleotide polymorphism at the position of 1 082 base pair caused the change of amino acid residue from Arg (3–79) to Lys (T582). The relative expression of the candidate gene in virescent plants was extensively lower than that in normal plants. Nullification of the gene by VIGS significantly turned the green leaf of normal cotton plants into yellow. We named this candidate gene as GhRVL.

[Conclusions] This study will facilitate the further research on virescent formation, and will be useful for breeding of hybrid cottons.

Map-based cloning of a recessive gene v1 for virescent leaf expression in cotton (Gossypium spp.)
ZHANG Youping, WANG Qiaolian, ZUO Dongyun, CHENG Hailiang, LIU Ke, ASHRAF Javaria, LI Simin, FENG Xiaoxu, YU John Z. and SONG Guoli
Journal of Cotton Research. 2018; 1:10.
https://doi.org/10.1186/s42397-018-0009-7

Identification and screening of nitrogen-efficient cotton genotypes under low and normal nitrogen environments at the seedling stage

[Background] Large quantities of nitrogen (N) fertilizer applied to cotton cropping systems support high yields but cause adverse environmental impacts such as N2O emission and water eutrophication. The development of cotton cultivars with higher N use efficiencies suitable for low-N conditions is therefore important for sustainable production. In this study, we evaluated 100 cotton genotypes in 2016 for N use efficiency and related traits at the seedling stage.

[Methods] Sand culture experiment was conducted with low N levels (0.01 g·kg−1) or normal N levels (0.1 g·kg−1). We investigated plant height, SPAD value (soil plant analysis development chlorophyll meter), dry weight, N accumulation, N utilization efficiency, and N uptake efficiency. Through descriptive statistics, principal component analysis and heatmap clustering analysis, we confirmed the evaluation index system of N-efficient genotypes and the classification of N-efficient genotypes.

[Results] Significant differences were observed among N levels and genotypes for all agronomic traits and N levels. Coefficients of variation varied greatly and ranged from 6.7~28.8 and 7.4~20.8 under low-N and normal-N treatment, respectively. All traits showed highly significant positive correlations with each other, except SPAD value. The principal components under both N levels were similar, showing that total dry weight, aboveground dry weight, total N accumulation, and N uptake efficiency were important components. We confirmed these four traits as suitable screening indexes for low N tolerance. Based on the results of heatmap clustering and scatter diagram analysis of N efficiency value, 10 genotypes were found low-N tolerant, in which five varieties were inefficient under both low and normal N conditions, while four varieties were found efficient under low-N conditions but inefficient under normal-N conditions. Only one variety was efficient under both low and normal-N conditions. Meanwhile, 20 genotypes were identified as low-N sensitive ones, in which 19 genotypes were inefficient under low-N conditions but efficient under normal-N conditions, one variety was inefficient under both low and normal-N conditions.

[Conclusion] We preliminarily identified Kashi as a low-N tolerant and N-efficient cotton genotype, and CCRI 64 as a low-N sensitive and N-inefficient cotton genotype. Further studies should be carried out to verify the yield and heritability effect of specific genotypes in the field.

Identification and screening of nitrogen-efficient cotton genotypes under low and normal nitrogen environments at the seedling stage
ZHANG Hengheng†, FU Xiaoqiong†, WANG Xiangru, GUI Huiping, DONG Qiang, PANG Nianchang, WANG Zhun, ZHANG Xiling and SONG Meizhen
†Contributed equally
Journal of Cotton Research. 2018; 1:6.
https://jcottonres.biomedcentral.com/articles/10.1186/s42397-018-0006-x

Analysis of short fruiting branch gene and Marker-assisted selection with SNP linked to its trait in upland cotton

[Background] With the rapid development of genomics, many functional genes have been targeted. Molecular marker assisted selection can accelerate the breeding process by linking selection to functional genes.

[Methods] In a study of upland cotton (Gossypium hirsutum L.), the F2 segregated population was constructed by crossing X1570 (short branches) with Ekangmian-13 (long branches) to identify the short fruiting branch gene and marker-assisted selection with SNP(Single Nucleotide Polymorphisms, SNP) linked to its trait.

[Result] The result demonstrated that linked SSR marker BNL3232 was screened by BSA(Bulked segregant analysis, BSA) method; one SNP locus was found, which was totally separated from the fruiting branches trait in upland cotton.

[Conclusion] It was verified that this SNP marker could be used for molecular assisted selection of cotton architecture.

Analysis of short fruiting branch gene and Marker-assisted selection with SNP linked to its trait in upland cotton
ZHANG Youchang, FENG Changhui, BIE Shu, WANG Xiaogang, ZHANG Jiaohai, XIA Songbo and QIN Hongde
Journal of Cotton Research. 2018; 1:5.
https://doi.org/10.1186/s42397-018-0001-2

Hypoxia tolerance studies for yield, fiber and physiological traits in cotton (Gossypium hirsutum L.)

[Background] Hypoxia tolerance studies in cotton are very rare in Pakistan. Unpredicted and excessive rainfalls result in severe losses to cotton crop in many regions of the country due to lack of hypoxia tolerance in current cotton varieties. The genotypes that can tolerate flooding are not reported earlier. The studies were conducted to explore hypoxia tolerance in local germplasm which will help to develop hypoxia tolerant cotton varieties.

[Method] An experiment with randomized complete blocks was designed to study the hypoxia tolerance in different cotton varieties. The genotypes were given two treatments i.e., water logged and non-water logged conditions.

[Results] The genotypes showed significant variability for yield, fiber and physiological traits. The hypoxia studies revealed that there is significant reduction for plant height in water sensitive genotype LRA-5166. The genotype MNH-786 showed better yield and MNH-556 showed superior ginning outturn percentage under water logged conditions. Staple length, strength and micronaire values also decreased under hypoxia. Similar pattern of negative effects were observed for Chlorophyll a, b contents and chl a/b ratio. Two hypoxia tolerant cultivars CIM-573 and MNH-564 had significantly higher chlorophyll a (1.664, 1.551) than other cultivars under both normal and waterlogged conditions. There was a significant decrease in total free amino acids in all genotypes/cultivars due to waterlogging. Free amino acid contents were significantly higher in two waterlogging sensitive cultivars, CEDIX and N-KRISHMA, than other cultivars under both non-waterlogged and waterlogged conditions. Waterlogging caused a significant reduction in shoot soluble proteins and increase in shoot proline. The genotype LRA-5166 was the highest in shoot soluble proteins content and showed significant decrease in shoot proline.

[Conclusions] With respect to yield MNH-786 showed better results and regarding ginning outturn percentage MNH-556 exhibited superior performance. The genotypes CIM-573 and MNH-564 showed higher chlorophyll a values. The above said genotypes may be exploited for further studies related to hypoxia tolerance.

Hypoxia tolerance studies for yield, fiber and physiological traits in cotton (Gossypium hirsutum L.)
HUSSAIN Altaf, FAROOQ Jehanzeb, AHMAD Saghir, MAHMOOD Abid, SADIQ M. Attiq, ZAFAR Ullah Zafar and ATHAR Habib-Ur-Rehman

Journal of Cotton Research. 2018; 1:8.
https://doi.org/10.1186/s42397-018-0008-8

Genotypic variation in spatiotemporal distribution of canopy light interception in relation to yield formation in cotton

[Background] Within-canopy interception of photosynthetically active radiation (PAR) impacts yield and other agronomic traits in cotton (Gossypium hirsutum L.). Field experiments were conducted to investigate the influence of 6 cotton varieties (they belong to 3 different plant types) on yield, yield distribution, light interception (LI), LI distribution and the relationship between yield formation and LI in Anyang, Henan, in 2014 and 2015.

[Result] The results showed that cotton cultivars with long branches (loose-type) intercepted more LI than did cultivars with short branches (compact-type), due to increased LI in the middle and upper canopy. Although loose-type varieties had greater LI, they did not yield significantly higher than compact-type varieties, due to decreased harvest index. Therefore, improving the harvest index by adjusting the source-to-sink relationship may further increase cotton yield for loose-type cotton. In addition, there was a positive relationship between reproductive organ biomass accumulation and canopy-accumulated LI, indicating that enhancing LI is important for yield improvement for each cultivar. Furthermore, yield distribution within the canopy was significantly linearly related to vertical LI distribution.

[Conclusion] Therefore, optimizing canopy structure of different plant type and subsequently optimizing LI distribution within the cotton canopy can effectively enhance the yield.

Genotypic variation in spatiotemporal distribution of canopy light interception in relation to yield formation in cotton
XING Fangfang, HAN Yingchun, FENG Lu, ZHI Xiaoyu, WANG Guoping, YANG Beifang, FAN Zhengyi, LEI Yaping, DU Wenli, WANG Zhanbiao, XIONG Shiwu, LI Xiaofei and LI Yabing

Journal of Cotton Research, 2018; 1:13.
https://jcottonres.biomedcentral.com/articles/10.1186/s42397-018-0012-z

Saponin synthesis and cotton growth is antagonistically regulated by solar UV-B radiation

An article of Journal of Cotton Research has been published online.

[Background] Earlier we have reported that the exclusion of solar UV-B increased the growth and yield of cotton plants as compared with ambient UV-B. The UV-B radiation effects on the saponins and the impact of ambient and reduced UV-B on the accumulation of saponins has not been investigated yet. Thus a field experiment was conducted to study the influence of solar UV-B on the growth response and saponin synthesis in cotton (Gossypium hirsutum) var. Vikram plants by the exclusion of UV-B. The cotton plants were grown in specially designed iron chambers, wrapped with filters that excluded UV-B (<315 nm), or transmitted ambient UV-B. [Results] Exclusion of ambient UV-B enhanced the growth of cotton plants in terms of plant height and leaf area. Greater plant height in UV-B excluded plants was due to elongated internode and more number of nodes. Enhancement in growth was accompanied by a decrease in the accumulation of saponins, which was quantified by the spectrophotometric, TLC and HPLC methods. Solvent extraction of saponins from the internodes and leaves were used for the bioassay of Amaranthus hypocotyl growth and expansion of cucumber cotyledons. Extracts obtained from the UV-B excluded plants (leaves and internodes) promoted the growth to a larger extent as compared with the extracts obtained from ambient grown plants.

[Conclusions] The result indicates that solar UV-B may possibly suppress the plant growth by regulating the synthesis of natural growth inhibitor’s like saponin.

Saponin synthesis and cotton growth is antagonistically regulated by solar UV-B radiation
DEHARIYA Priti, KATARIA Sunita, GURUPRASAD Kadur Narayan, PANDEY Govind Prakash

Journal of Cotton Research, 2018, 1:14

https://jcottonres.biomedcentral.com/articles/10.1186/s42397-018-0014-x

Light and simplified cultivation of cotton, an approach of global relevance?

A paper recently published about China

In a recent visit to Shadong Cotton Research Institute, I was introduced to the approach of carrying out new cultivation techniques destined to adapt to the current context of labor scarcity and high production costs for cotton production in China. This approach is being elaborated in a recent paper by the research team led by Prof. Dong HeZhong who is also a member of the Executive Committee of our Association.

The paper titled ‘Technologies and theoretical basis of light and simplified cotton cultivation in China’ is available here. The paper is not in open access, if needed, the corresponding author can be contacted (donghezhong@163.com ).

To me, the paper is interesting at least for two reasons. One, it gives a good view on how cotton is being cultivated in China, through an intensive way, in terms of production chemicals and knowledge.

Machine to sow single seed of cotton after garlic
Machine to sow single seed of cotton after garlic

Second, it provides scientific basis to sustain why some techniques, already finalized along the approach followed, work.

Plantlet obtained from single seed sowing are shorter, stronger and have a more rooting system
Plantlet obtained from single seed sowing are shorter, stronger and have a more developed rooting system
Industrial nursery can prevent farmers from producing plantlets by themselves
Industrial nursery can prevent farmers from producing plantlets by themselves

Semi-mechanized transplanting

Semi-mechanized transplanting

Potential relevance to other contexts?

The issue of producing cotton in a competitive way, notably against alternative crops in a same country, is common to many producing countries. The concern to decrease costs is global however cotton cultivation is intensive in capital and/or in chemical use. The concern to reduce labor cost is particularly felt in countries with production which is little mechanized, if not manual.

China is probably producing cotton by farms of the smallest size in the world, with average farm size of less than one hectare in traditional production regions of Yellow River and Yangtze River valleys. The way China has succeeded to conceive adapted mechanization, although there are still many challenges ahead, is worth consideration in many developing countries where farmers grow cotton on a few hectares each.

Where cotton is grown under irrigation in large areas, the various techniques China has been developing if not adopting in its North-western region is worth of consideration as well. The combination of sowing, fertilizing and posing mulching film is an example.

Machine for several operations in one time
Machine for several operations in one time

Environmental considerations worth being more explicitly highlighted as well?

Nowadays, there is a worldwide consensus on reducing at most the potential negative impacts in agricultural production in general, not only in cotton cultivation. To capture furthermore the attention on the Light and Simplified Cultivation approach, probably the potential environmental impacts that could result, either positive or negative, should be addressed too.

Seventh ‘Asian Cotton Research and Development Network’ Meeting, 15-17 Sept 2017, Nagpur India.

The Seventh Meeting of the Asian Cotton Research and Development Network was held at Nagpur during 15-17 September 2017. The Indian Society for Cotton Improvement (ISCI), Mumbai hosted the meeting together with the ICAR-CICR (Central Institute for Cotton Research), Nagpur and ICAR-CIRCOT (Central Institute for Research on Cotton Technologies). The main theme of the meeting was PRODUCING QUALITY FIBRE & DOUBLING COTTON FARMERS INCOME. Cotton researchers from public and the private sector participated. Dr. C. D. Mayee, President, Indian Society for Cotton Improvement, was the chairman, of the organizing Committee. The meeting elected Dr. Prashant G. Patil as Chairman of the Network until the next meeting. Eminent cotton experts i.e., Dr. Timorthy Dennehy, Dr Judith Brown, Dr Albert Santos from US; Dr Derek Russell from Australia, Dr Negm from Egypt and several senior research leaders from India and Bangladesh attended the meeting. The proceedings, recommendations, presentations and abstracts of the meeting can be accessed here.