Sorghum (Sorghum bicolor) is the fifth most popular crop worldwide and a C 4 model plant. Domesticated sorghum comes in many forms, including sweet cultivars with juicy stems and grain sorghum with dry, pithy stems at maturity. The Dry locus, which controls the pithy/juicy stem trait, was discovered over a century ago. Here, we found that Dry gene encodes a plant-specific NAC transcription factor. Dry was either deleted or acquired loss-of-function mutations in sweet sorghum, resulting in cell collapse and altered secondary cell wall composition in the stem. Twenty-three Dry ancestral haplotypes, all with dry, pithy stems, were found among wild sorghum and wild sorghum relatives. Two of the haplotypes were detected in domesticated landraces, with four additional dry haplotypes with juicy stems detected in improved lines. These results imply that selection for Dry gene mutations was a major step leading to the origin of sweet sorghum. The Dry gene is conserved in major cereals; fine-tuning its regulatory network could provide a molecular tool to control crop stem texture.
Key message
The importance and potential of the multi-purpose crop sorghum in global food security have not yet been fully exploited, and the integration of the state-of-art genomics and high-throughput technologies into breeding practice is required.
Abstract
Sorghum, a historically vital staple food source and currently the fifth most important major cereal, is emerging as a crop with diverse end-uses as food, feed, fuel and forage and a model for functional genetics and genomics of tropical grasses. Rapid development in high-throughput experimental and data processing technologies has significantly speeded up sorghum genomic researches in the past few years. The genomes of three sorghum lines are available, thousands of genetic stocks accessible and various genetic populations, including NAM, MAGIC, and mutagenised populations released. Functional and comparative genomics have elucidated key genetic loci and genes controlling agronomical and adaptive traits. However, the knowledge gained has far away from being translated into real breeding practices. We argue that the way forward is to take a genome-based approach for tailored designing of sorghum as a multi-functional crop combining excellent agricultural traits for various end uses. In this review, we update the new concepts and innovation systems in crop breeding and summarise recent advances in sorghum genomic researches, especially the genome-wide dissection of variations in genes and alleles for agronomically important traits. Future directions and opportunities for sorghum breeding are highlighted to stimulate discussion amongst sorghum academic and industrial communities.
The chilling requirement and heat requirement of 10 peach cultivars were investigated. And the relationship between chilling requirement and heat requirement, as well as the effect of different chilling accumulation on heat requirement were also systematically studied. There were no regular relations observed between vegetative buds and floral buds on the amount of chilling requirement or heat requirement. However, the distribution of chilling requirement and heat requirement followed certain rules respectively in vegetative buds and floral buds. Leaf buds with a lower chilling requirement usually had a lower heat requirement while flower buds with a lower chilling requirement usually had a higher heat requirement. Heat requirement was affected by the duration of chilling exposure. Regarding the deficient chilling exposure, although budburst exited, the budburst rate was far less than the requirement of production, and the heat requirement tended to infinity. In the matter of sufficient chilling exposure, heat requirement declined as chilling exposure increased. This research also revealed that there was a suitable quantity of chilling exposure which minimized the total time of chilling and heat exposure. Fig 6, Ref 37 Keywords peach; protected cultivation; budburst regulation; chilling requirement; heat requirement; quantitative relation CLC S662.101 : Q945.35 收稿日期:2011-09-23 接受日期:2011-10-28 * "十二五"国家科技支撑计划项目(No. 2011BAD12B02)和山东省优秀中青年科学家科研奖励基金(No. BS2011NY011)资助 Supported by the Key Sci-tech Project of the "12 th 5-year-plan" of China (No. 2011BAD12B02) and the Research Rewarding Funds of Shandong, China for Distinguished Young and Middle-aged Scientists (No. BS2011NY011)
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