Autogamy depression can be defined as the, "lowered viability of autogamous progeny relative to geitonogamous progeny”[1]. Viability has more often been evaluated in terms of percent fruit set or seed set rather than the fitness of progeny.[2][3] The experimental design for observing the occurrence of autogamy depression is called an "autogamy depression test" which has been described by researchers as analogous to a test for inbreeding depression.[1] The ability for fitness of autogamous progeny to differ from geitonogamous progeny comes from the understanding that plants can accumulate heritable mutational variation through both mitotic division and meiotic division.[3] Because plants have indeterminate growth, the apical meristems that contributes to the development of the reproductive structures of a plant have the potential to undergo continual mitosis resulting in the accumulation of somatic mutations (acquired mutations)[1]. Long lived plants can have higher per generation mutation rate, based on occurrences of more mitotic cell divisions compared to short lived plants.[2] Any deleterious mutations that are expressed during mitotic growth are filtered out through cell lineage selection, in which deleterious mutations that are subject to developmental selection are replaced by vigorous cell lineages; however, somatic mutations that are not expressed will not be subject to selection during growth of the plant and will accumulate in the apical meristem.[4]
Phenotypic effects of somatic mutations
editThere is evidence of the phenotypic effects of somatic mutations in increased Chlorophyll mutants of some long-lived plants. [5]
Expectations of the autogamy depression test
editIndividual crowns are treated as, "independent mitotic mutation-accumulation lines"[1] and so the appearance of deleterious somatic mutations in offspring from autogamous crosses will be heterozygous or homozygous at the same locus (~25% homozygous)[4] and the appearance of deleterious somatic mutations in offspring from geitonogamous crosses will be heterozygous.[1] Autogamy depression can be calculated through the simple equation AD = 1-(wa/wg), where AD is the Autogamy Depression, wa is the fitness of the autogamous progeny and wg is the fitness of the geitonogamous progeny. When the fitnesses are equal then AD is 0. The difference can be calculated by the equation, D = wg-wa.[2]
References
edit- ^ a b c d e Schultz, Stewart T.; Scofield, Douglas G. (2009-08-01). "Mutation Accumulation in Real Branches: Fitness Assays for Genomic Deleterious Mutation Rate and Effect in Large‐Statured Plants". The American Naturalist. 174 (2): 163–175. doi:10.1086/600100. ISSN 0003-0147.
{{cite journal}}: no-break space character in|first2=at position 8 (help); no-break space character in|first=at position 8 (help) - ^ a b c Bobiwash, K.; Schultz, S. T.; Schoen, D. J. (2013-10). "Somatic deleterious mutation rate in a woody plant: estimation from phenotypic data". Heredity. 111 (4): 338–344. doi:10.1038/hdy.2013.57. ISSN 1365-2540. PMC 3807267. PMID 23778990.
{{cite journal}}: Check date values in:|date=(help)CS1 maint: PMC format (link) - ^ a b Cruzan, Mitchell B.; Streisfeld, Matthew A.; Schwoch, Jaime A. (2018-08-16). "Phenotypic Effects of Somatic Mutations Accumulating during Vegetative Growth". bioRxiv: 392175. doi:10.1101/392175.
- ^ a b Cruzan, Mitchell B.,. Evolutionary biology : a plant perspective. New York, NY. ISBN 978-0-19-088268-6. OCLC 1050360688.
{{cite book}}: CS1 maint: extra punctuation (link) CS1 maint: multiple names: authors list (link) - ^ Klekowski, Edward J.; Godfrey, Paul J. (1989-08). "Ageing and mutation in plants". Nature. 340 (6232): 389–391. doi:10.1038/340389a0. ISSN 0028-0836.
{{cite journal}}: Check date values in:|date=(help)
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