Just recently the journal Nature published an article by a group who have sequenced a Chinese orchid Apostasia shenzhenica. This may seem a bit obscure as a subject, but it does throw some interesting light on the was that orchids as a whole have become what they are. It does not answer all the questions, but what it does do is give us a glimpse of how very small and simple changes can have a huge affect on the way in which a plant grows.
Among the interesting aspects of the research that was reported were comparisons of gene activity when compared with other orchid species and plants which were not orchids, but share common genes. Like all species, some basic genes are so fundamental that they appear in virtually all species. One of these is the gene AGL12. This gene seems to be fundamental in producing roots associated with terrestrial growth, as we find in our native British species. The epiphytic species have lost this gene and produce their typical root forms from another genetic process. In a similar way, the gene associated with production of lateral roots, another thing epiphytes tend not to do, is ANR1 and also lacking except in the terrestrial species. The team who did the work also recognised that the nature of orchid seeds, that is having no endosperm, seemed to be traceable to a conserved gene group widely found in other plants.
All of this work is based on automated systems and complicated statistical software, but it did surprise me that they had a little section on genome size estimation where they used this tremendous hammer to crack a nut. Estimating the genome size of the Apostasioideae as a group between 0.38pg and 5.96 pg. What was a surprise was that there is a very easy way of measuring the DNA mass of a cell by quantitatively dyeing it and then measuring the optical absorption, from which a simple calculation gives a figure in grams. I know this because I used to do it myself on cells and individual chromosomes. On second thoughts, it did take me a year to work out the details so that the results were reliable.
Anyway, the paper was quite fascinating and gave an insight into how small genetic changes can have a profound phenotypic affect. For example, once symbiotic germination is established the need for an endosperm is lost, so the gene becomes redundant and then symbiotic germination is essential to the ecology of the plant.
Among the interesting aspects of the research that was reported were comparisons of gene activity when compared with other orchid species and plants which were not orchids, but share common genes. Like all species, some basic genes are so fundamental that they appear in virtually all species. One of these is the gene AGL12. This gene seems to be fundamental in producing roots associated with terrestrial growth, as we find in our native British species. The epiphytic species have lost this gene and produce their typical root forms from another genetic process. In a similar way, the gene associated with production of lateral roots, another thing epiphytes tend not to do, is ANR1 and also lacking except in the terrestrial species. The team who did the work also recognised that the nature of orchid seeds, that is having no endosperm, seemed to be traceable to a conserved gene group widely found in other plants.
All of this work is based on automated systems and complicated statistical software, but it did surprise me that they had a little section on genome size estimation where they used this tremendous hammer to crack a nut. Estimating the genome size of the Apostasioideae as a group between 0.38pg and 5.96 pg. What was a surprise was that there is a very easy way of measuring the DNA mass of a cell by quantitatively dyeing it and then measuring the optical absorption, from which a simple calculation gives a figure in grams. I know this because I used to do it myself on cells and individual chromosomes. On second thoughts, it did take me a year to work out the details so that the results were reliable.
Anyway, the paper was quite fascinating and gave an insight into how small genetic changes can have a profound phenotypic affect. For example, once symbiotic germination is established the need for an endosperm is lost, so the gene becomes redundant and then symbiotic germination is essential to the ecology of the plant.
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