Adaptation to the local environment by modifications of the photoperiod response in crops

Abstract

Flowering plants produce a meristem at the shoot tip where specialized tissue generates shoot apical meristems at the appropriate time to differentiate into reproductive structures, pollinate and efficiently generate seeds. The complex set of molecular and phenological events culminating in development of a flowering meristem is referred to as 'flowering time'. Flowering time affects plant productivity because plants dedicate energy to produce flowers and seeds rather than vegetative tissue once the molecular decision to initiate flowering has been taken. Thus, initiation of flowering time is an important decision in plants, especially in annual plants including crops. Humans have introduced crops into latitudes and climate areas far from their origin or natural ecosystem, requiring in many cases modification of native flowering times. Recent molecular-genetic studies shed light on the genetic basis related to such introductions. In this review, recent progress regarding crop introductions and their genetic bases are summarized, as well as the potential of other agricultural plants to be introduced into different climatic zones.

Keywords: Circadian clock; Flowering time; Post-domestication spread.

Fig. 1

Photoperiodic flowering and post-domestication spread of crops. (A) Photoperiodic flowering of long-day and short-day plants. Long-day crops (wheat, barley, pea, lentil and sugar beet) flower under long days rather than under short days. Short-day crops (rice, maize, sorghum and wild potato) flower more efficiently under short days than under long days. (B) Post-domestication spread of crops. Long-day crops from south-west Asia and the Mediterranean, and short-day crops from south China, Africa, Mexico and the Andes are all grown at higher latitudes. Such spreading is closely associated with altered flowering times.

Fig. 2

Genes involved in photoperiodic flowering time regulation in some crops. (A) Genes involved in photoperiodic flowering regulation in the long-day plant Arabidopsis. Solid and dashed lines indicate direct and indirect regulation, respectively. (B) Genes involved in photoperiodic flowering in long-day crops. (C) Genes involved in photoperiodic flowering in short-day crops. In rice, CO up-regulates FT under long days, but down-regulates it under short days.