Euphytica 24 (1975) 369-370

A POSSIBLE CONTRIBUTION OF ENVIRONMENTALLY INDUCED CHANGES TO THE DOMESTICATION OF PLANTS
A. C. ZEVEN
Institute of Plant Breeding (IvP), Agricultural University, Wageningen, the Netherlands
Received 8 November 1974

SUMMARY

It is suggested that environmentally induced heritable changes may have played a role during plant domestication.

INTRODUCTION

DURRANT (1962a) discussed the various environmentally induced heritable changes that may occur. To these he added a new type the change of a plastic genotroph into a stable one. He (DURRANT, 1962a, 1962b) showed that plastic genotrophs change to stable ones under the influence of environment. The latter inherit their new property or properties to their progenies. He investigated this matter by growing plants of a plastic fibre flax variety Stormont Cirrus at two soil fertility levels. The plants grown on fertile soil became larger than the parent plants while the plants on poor soil grew shorter. This is in accordance to the expectation but unexpected is that for eight and more generations this difference in plant lengths remained despite of growing the tall (L) and short (S) plants in a same environment. The L-plants weigh 6 times the S-plant. According to TIMMIS & INGLE (1973) L-genotrophs possess 47-63 % more genes than S-genotrophs. Similar changes were obtained in Nicotiana rustica (HILL, 1965; PERKINS et al., 1973). An explanation of the origin of these changes is presented by BUSSEY & FIELDS (1974).

DURRANT (1962b) pointed out that such changes may be widespread and a potent factor in biological evolution. He did not work out this thought.

DOMESTICATION OF PLASTIC GENOTROPHS

Many domesticated plants probably derive from plants which grew on the compound of temporary or permanent camps, on rubbish and dung heaps. They may originate from plant or parts of them collected for some reason by man, brought to his camp and lost or thrown away there (for review see ZEVEN, 1975). They found on the camp area a soil fertility level higher than in the wild habitat. This higher level originated from 'household' refuse, human and animal excrements, corpses etc.

Among the plant species brought to the camp plastic genotrophs (like some wild flax and tobacco plants) probably occurred. These wild plants grew in a highly nutritional level they may have changed to larger stable genotrophs. In this environment stable genotrophs will have hybridized with each other resulting in epitrophic variation (DURRANT, 1962b). From these epitrophs some of our domesticants may derive.

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