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Post by mayz on Aug 8, 2012 4:26:32 GMT -5
Should i be seeing segregation in the seed? I thought seed coat was a maternal characteristic, but I must say I'm not really clear on this. In corn, I see segregation in the seed-coat. I think that this is primarily due to interactions with the underlying triploid and diploid layers which are different than the maternal genetics of the seed coat. For example: I see segregation of seed-coat thickness based on the genetics of the embryo. And, if the endosperm changes size a lot while drying and is tightly attached to a somewhat thin elastic seed-coat, then the seed coat is likely to wrinkle to match the underlying endosperm. I see this in corn. I think that peas may be similar. Note there's a difference as corn has albuminated seeds and pea has exalbuminated seeds (there isn't triploid tissue in mature seeds of pea) With two recessive alleles of R or Rb less starch is produced than normal. The cotyledons shrink during drying, and the seed coat wrinkles. So "wrinkled seeds" trait is linked to the genotype of embryo. |
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Post by mayz on Aug 8, 2012 4:57:25 GMT -5
Given my understanding of genetics nomenclature is sketchy, does this mean there are 4 possibilities at that locus - Pur, pur<a, pur<b, and pur? T four ones known, probably more |
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Post by mayz on Aug 8, 2012 5:13:15 GMT -5
Before I understood why, I used to be irritated with people that espoused Mendel's law of segregation. I realize today that it is because Mendel's segregation law only has practical application in very specialized circumstances: When two essentially homozygous cultivars are crossed and the offspring are selfed. There are just too many interactions going on within crosses of heterozygous populations for Mendelian genetics to be of much value to me as a landrace plant breeder. I understand today that Mendelian genetics is merely a stepping stone to introduce young students to a concept. Problem is that few ever go beyond that elementary school understanding, even in college. That isn't easy for the human's brain to understand that normality in biology is DIVERSITY. |
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