Genomic Designing of Climate-Smart Vegetable Crops by Chittaranjan Kole

Author:Chittaranjan Kole
Language: eng
Format: epub
ISBN: 9783319974156
Publisher: Springer International Publishing

Various numbers of genes and micro-RNAs (miRNAs) are involved in the regulation of flowering time, which help us to understand the involvement of these factors at the molecular level. Mainly, the photoreceptor proteins (phytochrome and/or cryptochrome) are controlling the photoperiodism, which is responsible for sensing red/far-red and blue light, respectively (Más et al. 2000). Photoperiod requirements are defined as either long day (LD) or short day (SD) with respect to the length of time of daylight. This photoperiod signal plays vital role in the floral development of several plant species, which is related to the annual cyclical seasonal changes, LD, coinciding with the spring and summer seasons, and SD, associated with the autumn and winter seasons, respectively (Corbesier and Coupland 2005).

Vernalization is defined as “the acquisition or acceleration of the ability to flower by a chilling treatment.” In A. thaliana, the prolonged exposure to cold will decrease the FLOWERING LOCUS C (FLC) expression, which acts as a floral repressor by inhibiting the activation of a set of genes required for transition of the apical meristem to a reproductive state (Kardailsky et al. 1999; Kobayashi et al. 1999; Michaels and Amasino 1999; Sheldon et al. 1999; Lee et al. 2000; Samach et al. 2000; Hepworth et al. 2002). Vernalization is an example of temperature-accelerated flowering (Song et al. 2012). When other specific conditions are met, including the presence of certain photoperiods and ambient temperatures, and vernalization, flowering only takes place many weeks or even months later (Kim et al. 2009).

B. rapa and B. oleracea show different responses to vernalization; B. rapa responds to seed vernalization, whereas B. oleracea requires plant vernalization (Lin et al. 2005). In seed-vernalization-responsive type, plants can sense low temperatures during seed germination. On the other hand, in plant-vernalization-responsive type, plants need to reach a certain developmental stage before they become sensitive to low temperatures (Friend 1985). In the plant-vernalization-responsive type, plants grow vegetative in the first year and flower in the following year after winter. B. napus is an important oilseed crop; natural variation in flowering time in response to vernalization was characterized into three groups (spring, winter, and semi-winter type) (Raman et al. 2016). Spring-type varieties are annual type generally seeded in spring and complete their life cycle in a single growing season without vernalization; winter (biennial) types have an obligate requirement usually seeded in the fall and complete development in the following spring under prolonged period of cold temperature. Semi-winter types are sown before winter, which gives flower after winter.

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