Current Advances in Molecular Basis and Mechanisms Regulating Leaf Morphology in Rice

Abstract

Yield is majorly affected by photosynthetic efficiency. Leaves are essential structure for photosynthesis and their morphology especially size and shape in a plant canopy can affect the rate of transpiration, carbon fixation and photosynthesis. Leaf rolling and size are considered key agronomic traits in plant architecture that can subsidize yield parameters. In last era, a number of genes controlling leaf morphology have been molecularly characterized. Despite of several findings, our understanding toward molecular mechanism of leaf rolling and size are under-developed. Here, we proposed a model to apprehend the physiological basis of different genes organized in a complex fashion and govern the final phenotype of leaf morphology. According to this leaf rolling is mainly controlled by regulation of bulliform cells by SRL1, ROC5, OsRRK1, SLL2, CLD1, OsZHD1/2, and NRL1, structure and processes of sclerenchyma cells by SLL1 and SRL2, leaf polarity by ADL1, RFS and cuticle formation by CFL1, and CLD1. Many of above mentioned and several other genes interact in a complex manner in order to sustain cellular integrity and homeostasis for optimum leaf rolling. While, leaf size is synchronized by multifarious interaction of PLA1, PLA2, OsGASR1, and OsEXPA8 in cell division, NAL1, NAL9, NRL1, NRL2 in regulation of number of veins, OsCOW1, OsPIN1, OsARF19, OsOFP2, D1 and GID in regulation of phytohormones and HDT702 in epigenetic aspects. In this review, we curtailed recent advances engrossing regulation and functions of those genes that directly or indirectly can distress leaf rolling or size by encoding different types of proteins and genic expression. Moreover, this effort could be used further to develop comprehensive learning and directing our molecular breeding of rice.

Structure‐function analysis of the maize bulliform cell cuticle and its potential role in dehydration and leaf rolling

“…Our findings add to prior observations that many leaf rolling mutants in rice or maize show alterations in BC size, number or adaxial/abaxial positioning (Gao et al., 2019; Nelson et al., 2002; Xu et al., 2018). Leaf architecture in general seems to be important, as histological analyses of a collection of 46 adaxially or abaxially rolled mutants in rice showed that changes of number, size, and pattern of BCs, sclerenchyma cells, parenchyma cells, and mesophyll cells as well as vascular bundles all could cause altered leaf rolling (Zou et al., 2014).…”

“…However, studies on leaf rolling in different grass types reach contradictory conclusions and could not resolve whether BCs cause rolling by collapse due to water loss, or whether their size and plasticity merely permit them to be compressed and allow rolling to occur (reviewed in Ellis, 1976; Evert, 2006; Moulia, 2000). Nevertheless, numerous mutants with altered BC number, size or adaxial/abaxial patterning, mostly identified in rice (Zou et al., 2014, reviewed in Xu et al., 2018) along with a few in maize (Gao et al., 2019; Nelson et al., 2002), show an effect on leaf rolling and underline the importance of this cell type and its distribution for the leaf rolling response in grasses. Only recently the genetic diversity of maize in combination with association mapping and machine learning techniques was employed to characterize the genetic basis of bulliform strip architecture, namely strip number and width, in a collection of diverse maize inbred lines, and identify a number of underlying candidate genes (Qiao et al., 2019).…”

Phenotypic plasticity of leaf anatomical traits helps to explain gas-exchange response to water shortage in grasses of different photosynthetic types

“…For instance, the balance between MS and BS is linked to photosynthetic capacity as those tissues are the place of carbon fixation by Rubisco in C3 and C4 species respectively (Carmo-Silva et al 2009). Presence of BL and SC cells may also impact in mechanical sustentation of leaves and the leaf rolling phenotyping, impacting in light interception (Monteith 1977) and photosynthesis (Xu et al 2018;Cal et al 2019). Moreover, higher ICS are related to a strategy to increase the exposition of chloroplasts in the mesophyll cells to intercellular spaces (Terashima et al 2011), where CO 2 is transported, increasing mesophyll conductance (Ouyang et al 2017).…”

Non-Invasive Morphological Characterization of Rice Leaf Bulliform and Aerenchyma Cellular Regions Using Low Coherence Interferometry

“…The non-destructive SS-OCT imaging modality was used here for the first time and was found to have considerable merits over conventional methods. To the best of our knowledge, morphological identification, leaf rolling assessment and small-vein cellular enumeration analysis were performed destructively in agriculture and have not been studied descriptively using OCT technology [52][53][54]. Rice leaf consists of multiple tissue layers, while these tissues constitute the photosynthesis system and nutrient transport pipeline of rice.…”