Investigations of the developmental stages sensitive to cold stress in the reproductive phase on a parent sorghum bicolor generation and their F1 hybrids

Sorghum, which is native to semi-arid areas, has developed a sensitivity to cold that is appropriate to its origin. Cold sensitivity or tolerance is conveyed occur during either the juvenile or reproductive phases of development. While the juvenile development phase mainly involves vegetative growth, the reproductive development phase involves the initiation of the multiplication of generative tissue. This project focuses on understanding cold tolerance of sorghum during the reproductive development phase. Cold tolerant and cold sensitive parental line, as well as F1s produced through reciprocal crosses, will be assessed. Reciprocal F1 hybrids will be produced though manual castration and allow us to exclude maternal and paternal effects. Varieties BBCH32, BBCH35, BBCH37, BBCH39, and BBCH51 will be exposed to cold stress at different developmental stages within climate chamber experiment. Pollen fertility will be studied by impedance flow cytometry, evaluation of pistil receptivity by fluorescence microscopy with annillin blue, panicle harvest index and phytohotmone regulation study by GC-MS. The aim of this work is to clarify physiological aspects of reproductive cold tolerance. It will also clarify the extent to which pistil receptivity is affected under cold conditions. Overall, this project should lead to new insights into the functioning of reproductive cold tolerance in Sorghum bicolor and thus to an improved understanding at the genetic and physiological level.