1e:T46f,Allotetraploid cotton is an economically important natural-fiber-producing crop worldwide. After polyploidization, Gossypium hirsutum L. evolved to produce a higher fiber yield and to better survive harsh environments than Gossypium barbadense, which produces superior-quality fibers. The global genetic and molecular bases for these interspecies divergences were unknown. Here we report high-quality de novo-assembled genomes for these two cultivated allotetraploid species with pronounced improvement in repetitive-DNA-enriched centromeric regions. Whole-genome comparative analyses revealed that species-specific alterations in gene expression, structural variations and expanded gene families were responsible for speciation and the evolutionary history of these species. These findings help to elucidate the evolution of cotton genomes and their domestication history. The information generated not only should enable breeders to improve fiber quality and resilience to ever-changing environmental conditions but also can be translated to other crops for better understanding of their domestication history and use in improvement.1f:T45c,Thermal imaging using infrared (IR) is now an established technology for the study of stomatal responses and for phenotyping plants for differences in stomatal behaviour. This paper outlines the potential applications of IR sensing in drought phenotyping, with particular emphasis on a description of the problems with extrapolation of the technique from the study of single leaves in controlled environments to the study of plant canopies is field plots, with examples taken from studies on grapevine (Vitis vinifera L.) and rice (Oryza sativa L.). Particular problems include the sensitivity of leaf temperature (and potentially the temperature of reference surfaces) to both temporal and spatial variation in absorbed radiation, with leaf temperature varying by as much as 15°C between full sun and deep shade. Examples of application of the approach to phenotyping in the field and the steps in data analysis are outlined, demonstrating that clear genotypic variation may be detected despite substantial variation in soil moisture status or incident radiation by the use of appropriate normalisation techniques.20:T48c,Upon assembling the first Gossypium herbaceum (A₁) genome and substantially improving the existing Gossypium arboreum (A₂) and Gossypium hirsutum ((AD)₁) genomes, we showed that all existing A-genomes may have originated from a common ancestor, referred to here as A₀, which was more phylogenetically related to A₁ than A₂. Further, allotetraploid formation was shown to have preceded the speciation of A₁ and A₂. Both A-genomes evolved independently, with no ancestor-progeny relationship. Gaussian probability density function analysis indicates that several long-terminal-repeat bursts that occurred from 5.7 million years ago to less than 0.61 million years ago contributed compellingly to A-genome size expansion, speciation and evolution. Abundant species-specific structural variations in genic regions changed the expression of many important genes, which may have led to fiber cell improvement in (AD)₁. Our findings resolve existing controversial concepts surrounding A-genome origins and provide valuable genomic resources for cotton genetic improvement.21:T6b7,

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