Once Should Have Been Enough: Gregor Mendel, “Experiments in Plant Hybridization”

2020 ◽  
pp. 75-100
Author(s):  
Allan Franklin ◽  
Ronald Laymon
HortScience ◽  
2005 ◽  
Vol 40 (4) ◽  
pp. 1003A-1003 ◽  
Author(s):  
Zhanao Deng ◽  
Brent Harbaugh

Caladiums (Caladium×hortulanum) are ornamental aroids often forced in containers or grown in the landscape for their colorful leaves. The aesthetic value of caladium plants is largely determined by their leaf characteristics. Caladium breeding can be traced back to the mid-1800s when Gregor Mendel conducted his plant hybridization experiments, but information on the inheritance of caladium traits has been rather scant. To understand the mode of inheritance for three typical leaf shapes and three main vein colors in caladium, controlled crosses were made among commercial cultivars and breeding lines, and segregation of leaf shape and/or main vein color in the progeny was analyzed. The observed segregation ratios indicated that a single locus with three alleles seemed to determine the main vein color in caladium. The white vein allele was dominant over the green vein allele, but recessive to the red vein allele, which was dominant over both white and green vein alleles. The three leaf shapes (fancy, lance, and strap) in caladium seemed to be controlled by two co-dominant alleles at one locus. Leaf shape segregation was skewed in some crosses, which might imply the existence of other factors involved in caladium leaf shape development. Chi-square tests revealed that leaf shape and main vein color were inherited independently in caladium.


2021 ◽  
Vol 113 (1) ◽  
pp. 107-135
Author(s):  
Bert Leuridan

Abstract Gregor Mendel, Thomas Hunt Morgan and experiments in classical geneticsIn the middle of the 19th century, Gregor Mendel performed a series of crosses with pea plants to investigate how hybrids are formed. Decades later, Thomas Hunt Morgan finalized the theory of classical genetics. An important aspect of Mendel’s and Morgan’s scientific approach is that they worked in a systematic, experimental fashion. But how did these experiments proceed? What is the relation between these experiments and Mendel’s and Morgan’s explanatory theories? What was their evidential value? Using present-day insights in the nature of experimentation I will show that the answer to these questions is fascinating but not obvious. Crossings in classical genetics lacked a crucial feature of traditional experiments for causal discovery: manipulation of the purported causes. Hence they were not traditional, ‘manipulative’ experiments, but ‘selective experiments’.


Author(s):  
Samir Okasha

There is no satisfactory one-line answer to the question ‘what exactly is a gene?’. The reasons why a precise definition is elusive are particularly interesting, and raise a number of philosophical subtleties. ‘Genes’ delves briefly into the history of genetics in order to understand them. It first looks at the work of Gregor Mendel in the 1860s and then the era of classical genetics in the 1920s and 1930s. It then moves on to molecular genetics, which came to fruition in the 1950s. How does the gene of Mendelian or classical genetics relate to the gene of molecular genetics? This question has long occupied philosophers of biology.


Sign in / Sign up

Export Citation Format

Share Document