{"id":12220,"date":"2022-03-21T15:56:08","date_gmt":"2022-03-21T19:56:08","guid":{"rendered":"https:\/\/carleton.ca\/biology\/?post_type=cu_event&#038;p=12220"},"modified":"2026-02-23T15:52:14","modified_gmt":"2026-02-23T20:52:14","slug":"the-mccully-plant-biology-lecture-2022","status":"publish","type":"cu_event","link":"https:\/\/carleton.ca\/biology\/event\/the-mccully-plant-biology-lecture-2022\/","title":{"rendered":"The McCully Plant Biology Lecture 2022"},"content":{"rendered":"<header class=\"mb-6 cu-pageheader cu-component-updated md:mb-12\">\n    <h1 class=\"cu-prose-first-last font-semibold !mt-2 mb-4 md:mb-6 text-3xl md:text-4xl lg:text-5xl lg:leading-[3.5rem] relative after:absolute after:h-px after:bottom-0 pb-5 after:w-10 after:bg-cu-red after:left-px\">\n        \n    <\/h1>\n    \n        <\/header>\n\n    \n    \n    \n    \n    <div class=\"cu-buttongroup cu-component-updated flex flex-wrap md:flex-1 gap-3 md:gap-5 justify-start\">\n                                                                        <\/div>\n    \n\n\n<p><a href=\"https:\/\/carleton.ca\/biology\/mccully-lecture\/\"><strong>Title: Understanding Complex Trait Evolution: A Case Study with C<sub>4<\/sub> photosynthesis. <\/strong><\/a><\/p>\n\n\n\n<p><a href=\"https:\/\/eeb.utoronto.ca\/profile\/sage-rowan-f\/\">Rowan F Sage, Department of Ecology and Evolutionary Biology, University of Toronto<\/a><\/p>\n\n\n\n<p><strong>Abstract:<\/strong> C<sub>4 <\/sub>photosynthesis independently evolved over 65 times in recent geological time, making it one of the most convergent of evolutionary phenomena in the living world. This is all the more remarkable considering C<sub>4<\/sub> photosynthesis is a complex trait involving evolutionary modification of hundreds to thousands of genes, and large sectors of leaf physiology and anatomy. Understanding why and how C<sub>4<\/sub> photosynthesis evolved could therefore provide insights into how complex traits evolve in the living world and do so repeatedly. In this presentation, I will discuss recent results from our group examining the C<sub>4<\/sub> evolutionary process.&nbsp; Using C<sub>3<\/sub>, C<sub>4<\/sub> and C<sub>3<\/sub>-C<sub>4<\/sub> intermediate species from over a dozen independent lineages, we demonstrate that C<sub>4<\/sub> photosynthesis evolved in hot, typically dry and\/or salinized environments where the inhibitory process of photorespiration is great in C<sub>3<\/sub> plants. The initial steps in C<sub>4<\/sub> evolution involved the formation of mechanisms to scavenge photorespired CO<sub>2<\/sub> and ammonia in the leaves of C<sub>3<\/sub> plants. This involved localizing the critical photorespiratory enzyme glycine decarboxylase into an inner tissue region of the leaf, typically the bundle sheath cells. By doing so, glycine produced in photorespiration must be transported into the bundle sheath for metabolism by GDC, releasing photorespired CO<sub>2<\/sub> and ammonia. Recovery of photorespired ammonia appears to be the critical early driver of C<sub>4<\/sub> evolution, in that initial upregulation of the C<sub>4<\/sub> pathway enzymes facilitate the recycling of the nitrogen in the ammonia produced by GDC back to mesophyll tissues. In addition to the enhancement of C<sub>4<\/sub> pathway enzymes, there are corresponding changes in plasmodesmatal density at the BS boundary to accelerate metabolite flux between the BS and mesophyll cells.&nbsp; This initiates the anatomical changes that lead to the C<sub>4<\/sub> Kranz anatomy. In short, complex trait evolution as demonstrated by C<sub>4<\/sub> evolution occurs as a series of small steps, each one facilitating subsequent steps. In the case of C<sub>4<\/sub> evolution, a need to scavenge photorespiratory products initiates the process, with the end result being a novel structure and function that leads to superior photosynthetic performance in higher plants.<\/p>\n\n\n\n<p><a href=\"https:\/\/carleton.ca\/biology\/wp-content\/uploads\/sites\/230\/McCully-Lecture-_Sage_2022_Poster.pdf\">McCully Lecture _Sage_2022_Poster<\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"template":"","meta":{"_acf_changed":false,"footnotes":"","_links_to":"","_links_to_target":""},"cu_event_type":[50],"cu_event_audience":[],"class_list":["post-12220","cu_event","type-cu_event","status-publish","hentry","cu_event_type-mccully-lecture"],"acf":{"cu_event_start_date":"2022-04-08T02:30:00","cu_event_end_date":"2022-04-08T03:30:00","cu_event_location_type":"in-person","cu_event_meeting_address_type":"on-campus","cu_building":"TB","cu_event_meeting_room":"210","cu_event_meeting_address_full":null,"cu_event_virtual_type":"tbd","cu_event_virtual_meeting_link":"","cu_post_thumbnail":false,"cu_event_cost":"","cu_event_registration":"","cu_event_secondary_button":"","cu_event_contact_name":"","cu_event_email":"","cu_event_phone":""},"_links":{"self":[{"href":"https:\/\/carleton.ca\/biology\/wp-json\/wp\/v2\/cu_event\/12220","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/carleton.ca\/biology\/wp-json\/wp\/v2\/cu_event"}],"about":[{"href":"https:\/\/carleton.ca\/biology\/wp-json\/wp\/v2\/types\/cu_event"}],"author":[{"embeddable":true,"href":"https:\/\/carleton.ca\/biology\/wp-json\/wp\/v2\/users\/2"}],"version-history":[{"count":3,"href":"https:\/\/carleton.ca\/biology\/wp-json\/wp\/v2\/cu_event\/12220\/revisions"}],"predecessor-version":[{"id":12252,"href":"https:\/\/carleton.ca\/biology\/wp-json\/wp\/v2\/cu_event\/12220\/revisions\/12252"}],"wp:attachment":[{"href":"https:\/\/carleton.ca\/biology\/wp-json\/wp\/v2\/media?parent=12220"}],"wp:term":[{"taxonomy":"cu_event_type","embeddable":true,"href":"https:\/\/carleton.ca\/biology\/wp-json\/wp\/v2\/cu_event_type?post=12220"},{"taxonomy":"cu_event_audience","embeddable":true,"href":"https:\/\/carleton.ca\/biology\/wp-json\/wp\/v2\/cu_event_audience?post=12220"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}