Changes in growth, water content and protein reflect embryo development inpecan (Carya illinoinensis)

The morphology, fresh and dry weights, and water content of pecan (Carya il linoinensis (Wangenh.) K. Koch) embryos were studied for three years, and s oluble and insoluble protein profiles characterized in trees grown in the s outheastern United States (Watkinsville, GA). Embryo development was divide d into histodifferentiation, cotyledon (Cot), maturation (Mat), and post-ab scission (PA) phases. Embryos became macroscopically visible at 97 d post p ollination (DPP), and developed through Cot and Mat stages for 20 and 32 d, respectively. Embryo fresh and dry weights increased rapidly during Cot an d Mat, and ceased upon ovule abscission. Water content declined during the same development period, with sharp declines during Mat and PA. The Cot sta ge was associated with expression of soluble proteins and later stages with insoluble proteins. Seasonal variations in embryo development were documen ted over the three year period. Percent water content and protein profiles were found to be useful in characterizing and defining the relative age of embryos during pecan development and were more reliable that chronological staging.