[Background] Salt stress significantly inhibits the growth, development, and productivity of cotton because of osmotic, ionic, and oxidative stresses. Therefore, the screening and development of salt tolerant cotton cultivars is a key issue towards sustainable agriculture. This study subjected 11 upland cotton genotypes at the seedling growth stage to five different salt concentrations and evaluated their salt tolerance and reliable traits.
[Results] Several morpho-physiological traits were measured after 10 days of salinity treatment and the salt tolerance performance varied significantly among the tested cotton genotypes. The optimal NaCl concentration for the evaluation of salt tolerance was 200 mmol·L− 1. Membership function value and salt tolerance index were used to identify the most consistent salt tolerance traits. Leaf relative water content and photosynthesis were identified as reliable indicators for salt tolerance at the seedling stage. All considered traits related to salt tolerance indices were significantly and positively correlated with each other except for malondialdehyde. Cluster heat map analysis based on the morpho-physiological salt tolerance-indices clearly discriminated the 11 cotton genotypes into three different salt tolerance clusters. Cluster I represented the salt-tolerant genotypes (Z9807, Z0228, and Z7526) whereas clusters II (Z0710, Z7514, Z1910, and Z7516) and III (Z0102, Z7780, Z9648, and Z9612) represented moderately salt-tolerant and salt-sensitive genotypes, respectively.
[Conclusions] A hydroponic screening system was established. Leaf relative water content and photosynthesis were identified as two reliable traits that adequately represented the salt tolerance of cotton genotypes at the seedling growth stage. Furthermore, three salt-tolerant genotypes were identified, which might be used as genetic resources for the salt-tolerance breeding of cotton.
[Title] Screening and evaluation of reliable traits of upland cotton (Gossypium hirsutum L.) genotypes for salt tolerance at the seedling growth stage
[Authors] SIKDER Ripon Kumar, WANG Xiangru, JIN Dingsha, ZHANG Hengheng, GUI Huiping, DONG Qiang, PANG Nianchang, ZHANG Xiling & SONG Meizhen
[Background] Fiber length is one of the primary quality parameters for the cotton industry when considering the textile performance and end-use quality of cotton. Currently, many decisions regarding cotton fiber length utilize the industry standard measurement device, i.e., the High Volume Instrument (HVI). However, it is documented that complete fiber length distributions hold more information than the currently reported HVI length parameters, i.e., upper half mean length (UHML) and uniformity index (UI). An alternative measurement device, the Advanced Fiber Information System (AFIS), is able to capture additional information about fiber length distribution. What is currently not known is how much additional information the AFIS length distribution holds.
[Results] The stability of differences in within-sample variation in fiber length captured by the AFIS length distribution by number characterizing differences between samples was deemed stable across the extended testing period. A diverse breeding population was evaluated and four significant sources of within sample variation in length were identified. A comparison of the ability between HVI length parameters and AFIS fiber length distribution to correctly categorize breeding lines to their family was performed. In all cases, the AFIS fiber length distribution more accurately identified germplasm families.
[Conclusions] The long-term stability test of the AFIS fiber length distribution by number shows that the measurement is stable and can be used to assess differences across samples. However, more information about within-sample variation in fiber length than that can be captured by length parameters is needed to assess differences across samples in many applications. Four length parameters outperform two length parameters when trying to identify the familial background of the samples in this set. These parameters characterize distributional shape differences that are not captured by the standard AFIS length parameters, UQL and short fiber content by number (SFCn). These findings suggest that additional types of variation in cotton fiber length are not captured and are therefore not currently used in most cotton breeding programs.
[Title] Stability, variation, and application of AFIS fiber length distributions
[Authors] HINDS Zachary, KELLY Brendan Robert & HEQUET Eric Francois
[Background] Gossypium hirsutum is highly susceptible to Verticillium wilt, and once infected Verticillium wilt, its yield is greatly reduced. But G. barbadense is highly resistant to Verticillium wilt. It is possible that transferring some disease-resistant genes from G. barbadense to G. hirsutummay contribute to G. hirsutum resistance to Verticillium wilt.
[Results] Here, we described a new gene in G. barbadense encoding AXMN Toxin Induced Protein-11, GbAt11, which is specifically induced by Verticillium dahliae in G. barbadense and enhances Verticillium wilt resistance in G. hirsutum. Overexpression in G. hirsutum not only significantly improves resistance to Verticillium wilt, but also increases the boll number per plant. Transcriptome analysis and real-time polymerase chain reaction showed that GbAt11overexpression can simultaneously activate FLS2, BAK1 and other genes, which are involved in ETI and PTI pathways in G. hirsutum.
[Conclusions] These data suggest that GbAt11 plays a very important role in resistance to Verticillium wilt in cotton. And it is significant for improving resistance to Verticillium wilt and breeding high-yield cotton cultivars.
[Title] GbAt11 gene cloned from Gossypium barbadense mediates resistance to Verticillium wilt in Gossypium hirsutum
[Authors] QIU Tingting, WANG Yanjun, JIANG Juan, ZHAO Jia, WANG Yanqing & QI Junsheng
Abstract: Recently, Wang et al. systematically explored the transcription landscape in diploid cotton Gossypium arboreum. In the study, they integrated four high-throughput sequencing techniques, including Pacbio sequencing, strand-specific RNA sequencing (ssRNA-seq), Cap analysis gene expression sequencing (CAGE-seq), and PolyA sequencing (PolyA-seq) to profile the RNA transcriptome of G. arboreum. They developed a pipeline, IGIA to construct accurate gene structure annotation based on the updated genome of G. arboreum and the multi-strategic RNA-seq data. Their study revealed some intriguing phenomena and potential novel mechanisms in the regulation of RNA transcription in plants, and also provided valuable resources for further functional genomic research in cotton.
[Title] Towards complete deconstruction of cotton transcriptional landscape
[Author] LI Fuguang