About this Research Topic
In the past ten years, there have been tremendous advances in understanding regulatory systems for flowering and other developmental processes related to FLOWERING LOCUS T (FT) genes, as the underlying basis of the long-sought “florigen” in higher plants. Discoveries have revealed a network of regulatory components related to photoperiod, phytochrome, and circadian factors, as well as hormones, and environmental factors. Additionally, the regulatory systems for cold temperature regulation in temperate-zone plants have been revealed to involve vernalization factors that interact with the FT network. In the moderate to warm temperature range, additional regulatory factors are thought to be involved, particularly among tropical plants, although only a limited number of reports have addressed such regulatory aspects in tropical plants. Regulatory cues that play important roles in reproductive development in tropical environments, such as annual cycles of wet and dry seasons, have also received relatively limited attention.
Recent discoveries have revealed that photoperiod regulation of non-floral systems also involve FT genes related to regulatory processes such as potato tuberization, and onion bulb development. Storage roots in crops such as cassava, yams and sweet potatoes are among the most important staples in the tropics. However, information on their regulatory systems is limited and merits greater attention. In many crops for which the harvested organs are storage roots, and are typically reproduced vegetatively, poor flowering limits the ability of crop breeders to produce sufficient progeny of desired crosses.
Flowering in cassava faces an additional problem because it is closely linked to plant architecture. Late flowering results in erect plant architecture, which is often required by farmers, favors mechanization and represents a key adaptive trait for climate change. However, breeding erect-type cassava is difficult and inefficient. The linkage between flowering and plant architecture has prevented systematic efforts to introduce inbreeding in cassava genetic enhancement, therefore limiting the beneficial effects that genomic selection may offer to the crop. Studies on developing cassava-related methods of inducing flowering with extended daylength are underway, with the aim of improving flower production with plant growth regulators. In sweet potato and cassava, grafting approaches have been used to improve flowering, while genetic markers identify the sex of yam plants and accelerate breeding efforts. These recent advances merit further attention by the scientific community.
Thus, considering the gap in the knowledge around reproductive biology of some important tropical crops, this Research Topic aims to showcase recent findings on flower biology and genetic/physiological factors affecting it, including in vitro and in vivo assessment of pollen viability, pollen conservation, embryo development, fruit and seed set, alteration of female/male flowers (or plants) ratio and protocols to improve them. This information will ultimately make the breeding of vegetatively propagated tropical crops more efficient. Please note, studies addressing grain crops such as cereals and legumes are not welcome.
Keywords: Induction of Flowering, Embryo Development, Doubled Haploids, Photoperiod, Plant Growth Regulators
Important Note: All contributions to this Research Topic must be within the scope of the section and journal to which they are submitted, as defined in their mission statements. Frontiers reserves the right to guide an out-of-scope manuscript to a more suitable section or journal at any stage of peer review.