A stomatal model of anatomical tradeoffs between gas exchange and pathogen colonization

Abstract

2Stomatal pores control both leaf gas exchange and are an entry for many plant pathogens, 3 setting up the potential for tradeoffs between photosynthesis and defense. To prevent colonization 4 and limit infection, plants close their stomata after recognizing pathogens. In addition to closing 5 stomata, anatmoical shifts to lower stomatal density and/or size may also limit pathogen 6 colonization, but such developmental changes would permanently reduce the gas exchange 7 capacity for the life of the leaf. I developed and analyzed a spatially explicit model of pathogen 8 colonization on the leaf as a function of stomatal size and density, anatomical traits which 9 determine maximum rates of gas exchange. The model predicts greater stomatal size or density 10 increases colonization, but the effect is most pronounced when stomatal cover is low. I also 11 derived scaling relationships between stomatal size and density that preserves a given probability 12 of colonization. These scaling relationships set up a potential conflict between maximizing defense 13 and minimizing stomatal cover. To my knowledge, this is the first mathematical model connecting 14 gas exchange and pathogen defense via stomatal anatomy. It makes predictions that can be 15 tested with experiments and may explain variation in stomatal anatomy among plants. The model 16 is generalizable to many types of pathogens, but lacks significant biological realism that may be 17 needed for accurate predictions. 18 19 20 Berry et al., 2010; Chater et al., 2017), but many plant pathogens take advantage of these chinks in the 21 leaf cuticular armor to infect prospective hosts (Zeng et al., 2010; McLachlan et al., 2014; Melotto et al., 22 2017). The density and size of stomata set the anatomical maximum rate of stomatal conductance to CO 2 23 and water vapor (Brown Harrison et al., 2019), but 25 the pore area shrinks and expands in response to internal and external factors to regulate gas exchange 26 dynamically (Buckley, 2019). Many plant pathogens, including viruses (Murray et al., 2016), bacteria 27 ( Melotto et al., 2006; Underwood et al., 2007), protists (Fawke et al., 2015), and fungi (Hoch et al., 1987; 28 Zeng et al., 2010) use stomatal pores to gain entry into the leaf. Since stomatal conductance is a major 29 limitation on photosynthesis (Farquhar and Sharkey, 1982; Jones, 1985) while pathogens reduce fitness, 30 this sets up a potential tradeoff between increased photosynthesis and defense against pathogens. Although 31 there have been many empirical studies on the effect that pathogens have on stomata, there is no theoretical 32 1 Muir et al. Stomata tradeoff photosynthesis for defenseframework in which to place these findings. Lack of a theoreatical framework makes it difficult to answer 33 general questions about how selection for pathogen defense constrains maximum rates of gas exchange. 34Stomatal anatomy is the key link between gas exchange and pathogen colonization. The density and 35 size of stomata not on...

Ciri Adaptasi Anatomi Daun Bougainvillea spectabilis W. Yang Dijangkiti Virus Bougainvillea chlorotic vein-banding

“…Penutupan liang stomata menyebabkan perubahan fisiologi berlaku dalam stomata seperti penurunan dalam saiz dan kepadatan stomata. Perubahan ini menyebabkan kapasiti pertukaran gas dalam tumbuhan tersebut menurun secara kekal (Muir 2019). Kajian Melotto et al (2017) juga menyatakan tumbuhan dapat mengawal kolonialisasi patogen secara fizikal dengan menutup stomata.…”