Genetic basis controlling rice plant architecture and its modification for breeding

Abstract

The shoot and root system architectures are fundamental for crop productivity. During the history of artificial selection of domestication and post-domestication breeding, the architecture of rice has significantly changed from its wild ancestor to fulfil requirements in agriculture. We review the recent studies on developmental biology in rice by focusing on components determining rice plant architecture; shoot meristems, leaves, tillers, stems, inflorescences and roots. We also highlight natural variations that affected these structures and were utilized in cultivars. Importantly, many core regulators identified from developmental mutants have been utilized in breeding as weak alleles moderately affecting these architectures. Given a surge of functional genomics and genome editing, the genetic mechanisms underlying the rice plant architecture discussed here will provide a theoretical basis to push breeding further forward not only in rice but also in other crops and their wild relatives.

Leaf- and diverged shoot meristem programs shape the stem in rice

“…There is another non-elongating part at the bottom, which we recently named the foot ( Fig. 1a ) 7,8 . The foot also does not elongate but forms vascular networks connected to the axillary buds ( Supplemental Fig.…”

“…This is probably due to the lack of clear landmarks in stem morphology in many species 6 . Grasses, including rice, are excellent models for studying stem development because distinctions among stem domains (nodes and internodes) and neighboring organs are clear 7,8 ( Fig. 1a ).…”

Heat-shock inducible clonal analysis reveals the stepwise establishment of cell fates in the rice stem

“…In rice, there is another non-elongating portion beneath internodes, which has not been well characterized yet (Figure 1, A and B). We recently named this region "foot" (Tanaka et al, 2023). Although the foot shares a central cavity with the above internode at maturity (Figure 3B), it is a chlorophyll-less and non-elongating tissue in which vascular bundles from the axillary bud connect to those of the stem (Figure 1A, 3D,G).…”

The Function of Florigen in the Vegetative-to-Reproductive Phase Transition in and around the Shoot Apical Meristem

“…2013 , Tanaka et al. 2013 , 2023 ). During the vegetative phase, the SAM drives the continuous formation of leaves and stems, including nodes and internodes, with leaf development being the hallmark of this phase.…”